The Hidden Danger in Your Next Production: The Complete Guide to Theatrical Fog and Dust Safety Standards

You have spent months planning the perfect production. The lighting is dialed in. The sound design is flawless. The set pieces are works of art. And that atmospheric fog effect you have been dreaming about? It is going to transform your stage into something truly magical.

Opening night arrives. The house lights dim. The fog rolls across the stage, catching the light in ways that make the audience gasp. Your artistic vision has come to life.

But here is the question that keeps safety consultants up at night: Do you actually know what is in the air your performers are breathing? Do you understand the chemical composition of that beautiful haze drifting through your venue? Have you considered what happens when your fog machine overheats? And that dust effect you are planning for the second act, have you assessed whether it could create an explosive atmosphere?

I have been in this industry long enough to see productions get everything right creatively while getting safety catastrophically wrong. I have witnessed performers develop chronic respiratory conditions. I have seen productions shut down by fire marshals who recognized explosion hazards that the production team missed entirely. I have consulted on cases where venues faced significant liability because they failed to implement proper safety protocols.

The good news? It does not have to be that way. The American National Standards Institute has developed comprehensive standards specifically for theatrical fog and dust effects. These standards represent decades of research, countless hours of expert deliberation, and hard-won lessons from incidents that never should have happened.

This guide will take you through everything you need to know about ANSI E1.5-2009 (R2014) and ANSI E1.40-2016. By the time you finish reading, you will understand not just what these standards require, but why they require it, how to implement them in your productions, and how to build a culture of safety that protects everyone who walks onto your stage.

Let me break down exactly what you need to know.

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Part One: Understanding the Stakes

Why Atmospheric Effects Safety Matters More Than You Think

Theatrical fog and dust effects are not just aesthetic choices. They are not simply tools in your creative toolkit. They are potential health hazards that require the same level of attention you give to rigging inspections, electrical safety, or fall protection.

Every time you activate a fog machine, you are introducing aerosolized chemicals into a shared breathing space. Every time you deploy a dust effect, you are creating conditions that could, under the wrong circumstances, lead to a dust explosion. These are not theoretical risks. They are documented hazards with real-world consequences.

Here is the reality that too many production professionals either do not know or choose to ignore:

Glycol-based theatrical fog can cause respiratory irritation, throat discomfort, and in some cases, trigger asthma attacks or other respiratory events. Studies conducted by the Mount Sinai School of Medicine and other research institutions have documented respiratory symptoms in performers regularly exposed to theatrical fog. These symptoms include coughing, wheezing, chest tightness, and reduced lung function.

Certain dust effects can create explosive atmospheres. The National Fire Protection Association has documented numerous dust explosions in industrial settings. The same principles apply to theatrical dust. When fine particles are suspended in air at the right concentration, and an ignition source is present, the result can be catastrophic.

Decomposition products from overheated fog machines include formaldehyde, acrolein, and acetaldehyde. These are not minor irritants. Formaldehyde is classified as a known human carcinogen by the International Agency for Research on Cancer. Acrolein is a severe respiratory irritant that can cause pulmonary edema at high concentrations. Acetaldehyde is classified as possibly carcinogenic to humans.

This is not fear-mongering. This is science. This is the documented reality of what happens when atmospheric effects are used without proper controls.

And here is what makes this even more critical: the people most at risk are often the least protected. Performers who are singing, dancing, and exerting themselves physically have elevated respiration rates. They are breathing deeper and more frequently than the average person. They are inhaling more of whatever is in the air. And they are often doing so for extended periods, night after night, week after week, throughout a production’s run.

The History Behind the Standards

To understand why these standards exist, you need to understand the history that led to their development.

The use of theatrical fog dates back centuries. Early productions used actual smoke from burning materials to create atmospheric effects. This was obviously hazardous, but in an era before modern safety regulations, it was accepted practice.

The development of modern fog machines in the mid-20th century seemed like a major safety improvement. Instead of actual combustion products, these machines vaporized glycol-based fluids to create a visually similar effect without open flames. The entertainment industry embraced this technology enthusiastically.

But questions began to emerge. What were performers actually breathing? What were the long-term health effects of repeated exposure? Were there limits to how much fog was safe?

In the 1990s, Actors’ Equity Association, the union representing professional stage actors and stage managers in the United States, began raising concerns about theatrical fog exposure. Members were reporting respiratory symptoms. Some were developing chronic conditions. The union demanded answers.

This led to a series of research studies examining the health effects of theatrical fog. The studies confirmed what many suspected: while glycol-based fog was certainly safer than actual smoke, it was not without risks. At high concentrations, it could cause respiratory irritation. For individuals with pre-existing respiratory conditions, even moderate concentrations could trigger symptoms.

The Entertainment Services and Technology Association, working with ANSI, convened expert panels to develop science-based standards for theatrical fog use. The result was ANSI E1.5, first published in 2009 and reaffirmed in 2014.

A similar process led to the development of ANSI E1.40 for theatrical dust effects. While less commonly used than fog, dust effects present their own unique hazards, particularly the risk of dust explosions. The 2016 standard provides comprehensive guidance for managing these risks.

These standards did not emerge from theoretical concerns. They emerged from real incidents, documented health effects, and the recognition that the entertainment industry needed clear, science-based guidelines for protecting performers and crew.

The Scope of the Problem

How widespread is the use of theatrical fog, smoke, and dust? The answer is: far more extensive than most people realize.

Theatrical fog is used in virtually every sector of the entertainment industry:

Theater: From Broadway productions to community theater, fog effects are used to create atmosphere, enhance lighting effects, and simulate environmental conditions. A single production might use fog in dozens of scenes over hundreds of performances.

Concert Venues: Modern concert productions rely heavily on atmospheric effects. Haze is used to make lighting effects visible. Fog is used for dramatic reveals and set pieces. A major touring production might deploy these effects in venues around the world, night after night.

Theme Parks: The themed entertainment industry uses fog extensively. Haunted attractions, immersive experiences, and special effects all rely on atmospheric effects. Millions of guests pass through these fog-enhanced environments annually.

Film and Television: On-set atmospheric effects are standard practice in film and television production. Interior scenes, exterior scenes, day or night, fog and haze help cinematographers create the visual textures that make productions look polished and professional.

Corporate Events: Even the corporate events sector uses theatrical fog. Product launches, award ceremonies, and trade show presentations all employ atmospheric effects to create memorable experiences.

Houses of Worship: Many churches and religious organizations use theatrical fog during services, particularly during musical performances and special holiday programs.

Nightclubs and Entertainment Venues: Fog and haze are standard features of nightclub environments, running for hours at a time, night after night.

When you consider the scope of use, the number of people potentially exposed, and the frequency of exposure, the importance of proper safety standards becomes clear. This is not a niche concern affecting a small number of people. This is a widespread practice affecting millions of performers, crew members, and audience members around the world.

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Part Two: The Science of Theatrical Fog

Understanding Glycol-Based Fog

Before we dive into the standards themselves, it is essential to understand what theatrical fog actually is and how it works. This scientific foundation will help you understand why the standards require what they require.

The most common theatrical fog is produced by heating a mixture of water and glycols. The term “glycol” refers to a class of organic compounds characterized by two hydroxyl groups attached to different carbon atoms. The glycols most commonly used in theatrical fog fluids are:

Propylene Glycol: This is a synthetic compound with the chemical formula C3H8O2. It is classified as “generally recognized as safe” by the U.S. Food and Drug Administration for use in food and pharmaceuticals. Propylene glycol is used in everything from food flavoring to pharmaceutical preparations to cosmetics. In theatrical fog, it serves as the primary fog-producing agent.

Glycerin (Glycerol): This is a naturally occurring compound with the chemical formula C3H8O3. Like propylene glycol, glycerin is widely used in food, pharmaceuticals, and cosmetics. It produces a denser, slower-dissipating fog than propylene glycol alone.

Triethylene Glycol: This compound is sometimes used in fog fluid formulations, particularly for producing longer-lasting haze effects. It has a higher boiling point than propylene glycol, which affects the characteristics of the fog produced.

When these fluids are heated in a fog machine, they vaporize and then recondense in the cooler air outside the machine, forming small droplets that scatter light and create the visible fog effect. The size of these droplets, their concentration in the air, and their chemical composition all affect both the visual appearance of the fog and its potential health effects.

The Aerosol Factor

Understanding theatrical fog requires understanding aerosol science. An aerosol is a suspension of fine solid particles or liquid droplets in a gas. When you see theatrical fog, you are seeing light scattered by millions of tiny liquid droplets suspended in the air.

These droplets vary in size, typically ranging from less than one micrometer to several micrometers in diameter. Particle size matters enormously for health effects:

Particles larger than 10 micrometers: These are typically filtered out by the nose and throat. They do not penetrate deeply into the respiratory system.

Particles between 2.5 and 10 micrometers: These can penetrate into the bronchi and bronchioles, the branching airways of the lungs.

Particles smaller than 2.5 micrometers: These can penetrate into the alveoli, the tiny air sacs where gas exchange occurs. This is the deepest part of the respiratory system, and particles that reach this region can have significant health effects.

The droplets produced by theatrical fog machines span this range of sizes. The exact size distribution depends on the fog machine’s design, the fluid composition, the operating temperature, and environmental conditions like humidity and air movement.

This is why exposure limits for theatrical fog are measured in milligrams per cubic meter. This measurement captures the total mass of aerosol particles in a given volume of air, regardless of the number or size of individual particles.

Thermal Decomposition: The Hidden Hazard

One of the most significant safety concerns with theatrical fog is thermal decomposition. When glycol-based fluids are heated above their optimal operating temperatures, they begin to break down into other compounds. Some of these decomposition products are significantly more hazardous than the original fluids.

The primary decomposition products of concern include:

Formaldehyde (CH2O): This colorless gas with a strong, pungent odor is classified as a known human carcinogen. It can cause irritation of the eyes, nose, and throat at low concentrations. At higher concentrations, it can cause more severe respiratory effects. Chronic exposure has been linked to nasopharyngeal cancer and leukemia.

Acetaldehyde (C2H4O): This compound is classified as possibly carcinogenic to humans. It can cause irritation of the eyes, skin, and respiratory tract. It has a fruity odor that can be detected at relatively low concentrations.

Acrolein (C3H4O): This is one of the most toxic decomposition products. It is a severe respiratory irritant that can cause pulmonary edema at high concentrations. Even at low concentrations, it can cause significant eye and respiratory irritation.

The formation of these decomposition products is directly related to temperature. When fog machines operate within their specified temperature ranges, decomposition is minimal. When machines malfunction, when heating elements become fouled with residue, or when machines are operated outside their design parameters, decomposition increases dramatically.

This is why the ANSI standards place such emphasis on equipment maintenance and proper operation. A well-maintained fog machine operating correctly produces relatively benign aerosols. A poorly maintained or malfunctioning machine can produce significant quantities of toxic decomposition products.

Fluid Composition Matters

Not all fog fluids are created equal. The market includes a wide range of products with varying compositions, and these differences matter for both performance and safety.

High-quality fog fluids are specifically formulated to:

• Vaporize efficiently at the machine’s operating temperature
• Produce droplets in the optimal size range for visual effect
• Minimize decomposition at normal operating temperatures
• Produce fog with the desired density and hang time

Lower-quality fluids may use less refined ingredients, contain impurities, or be formulated for machines other than the one being used. Using the wrong fluid in a fog machine can lead to poor performance, increased decomposition, and potentially hazardous emissions.

The ANSI standards recognize this by requiring that fog fluids be appropriate for the equipment being used and that Safety Data Sheets be reviewed to understand the specific hazards of each product.

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Part Three: ANSI E1.5-2009 (R2014) In Depth

The Standard’s Structure and Purpose

The ANSI E1.5-2009 (R2014) standard, titled “Theatrical Fog Made with Aqueous Solutions of Di- and Trihydric Alcohols,” provides comprehensive guidance for the safe use of glycol-based theatrical fog. Understanding this standard thoroughly is essential for anyone responsible for production safety.

The standard addresses several key areas:

1. Scope and applicability
2. Exposure limits for fog aerosols
3. Exposure limits for decomposition products
4. Monitoring requirements and methodologies
5. Equipment requirements and maintenance
6. Administrative controls and best practices

Let us examine each of these areas in detail.

Scope and Applicability

The standard applies specifically to theatrical fog made from aqueous (water-based) solutions containing dihydric alcohols (compounds with two hydroxyl groups, like propylene glycol) and trihydric alcohols (compounds with three hydroxyl groups, like glycerin).

This scope is important because it defines what the standard covers and what it does not. The standard does not cover:

Oil-based fog fluids: Some theatrical effects use mineral oil-based fluids. These have different health implications and are not addressed by this standard.

Dry ice fog: Fog produced by sublimating solid carbon dioxide operates on completely different principles and presents different hazards.

Cryogenic fog: Fog produced by liquid nitrogen or other cryogenic materials is outside the scope of this standard.

Smoke effects from combustion: Actual smoke produced by burning materials is not covered.

If you are using any of these alternative atmospheric effects, you will need to reference other standards and guidelines. For glycol-based fog, which represents the vast majority of theatrical fog use, ANSI E1.5 is your primary reference.

Exposure Limits Explained

The heart of ANSI E1.5 is its establishment of exposure limits for theatrical fog. These limits are expressed as concentrations of aerosol in the air, measured in milligrams per cubic meter (mg/m³).

Time-Weighted Average (TWA): 10 mg/m³

The TWA is the average concentration over an eight-hour work shift. This limit recognizes that exposure is cumulative. A performer who breathes relatively clean air for part of a shift but is exposed to dense fog during certain scenes will have an average exposure somewhere between those extremes.

The 10 mg/m³ TWA is designed to protect workers who are exposed to theatrical fog regularly over extended periods. At this concentration, most healthy individuals should not experience significant adverse effects.

Short-Term Exposure Limit (STEL): 40 mg/m³

The STEL is the maximum concentration that should be allowed for any 15-minute period. This limit recognizes that short-term exposures to higher concentrations can occur during certain scenes or effects, but these exposures must be limited in duration.

The 40 mg/m³ STEL allows for dramatic fog effects during specific moments in a production while still protecting performers from acute respiratory irritation.

Understanding These Numbers in Practice

What do these concentrations actually mean in terms of visible fog? This is where things get complicated, because the relationship between concentration and visibility depends on many factors, including particle size distribution, lighting conditions, and the specific fluid being used.

As a general guideline:

• At 10 mg/m³, you will see a distinct haze in the air, particularly when highlighted by lighting. However, you will still have good visibility across a typical stage.
• At 40 mg/m³, you will see moderately dense fog. Visibility will be somewhat reduced, but you will still be able to see clearly across a stage.
• At concentrations above 100 mg/m³, you begin to approach the dense, visibility-reducing fog often desired for dramatic effects.

This creates an inherent tension between artistic desires and safety requirements. The densest, most visually dramatic fog effects often exceed safe exposure limits. This is why the standards emphasize time limitations and the importance of not exceeding the STEL, even for short periods.

The Science Behind the Limits

Where do these specific numbers come from? The exposure limits established in ANSI E1.5 are based on occupational health research and toxicological data.

Propylene glycol has been extensively studied due to its widespread use in food, pharmaceuticals, and other applications. The available research indicates that:

• Propylene glycol has low acute toxicity when inhaled
• At high concentrations, it can cause respiratory irritation
• There is no evidence of carcinogenicity or significant chronic toxicity at occupational exposure levels
• Individuals with pre-existing respiratory conditions may be more sensitive

The 10 mg/m³ TWA and 40 mg/m³ STEL were established to provide a significant margin of safety based on this research. These limits are more conservative than the occupational exposure limits for propylene glycol established by organizations like the American Industrial Hygiene Association, reflecting the unique exposure circumstances in theatrical settings where performers may be exerting themselves physically while exposed.

Monitoring Requirements

The ANSI standard specifies that exposure monitoring should be conducted to verify compliance with the exposure limits. This monitoring must be done using appropriate instrumentation and methodologies.

Aerosol Monitors

The standard recommends using real-time aerosol monitors capable of measuring particle concentrations in the air. These devices use optical sensors to detect light scattered by particles and calculate the concentration based on this measurement.

Several types of aerosol monitors are suitable for theatrical fog monitoring:

Photometric monitors: These devices use a light source and a detector to measure light scattered by particles. They provide real-time readings of particle concentration.

Gravimetric samplers: These devices draw air through a filter over a specified time period. The filter is weighed before and after sampling to determine the mass of particles collected. While highly accurate, these provide time-averaged measurements rather than real-time data.

Direct-reading mass monitors: These advanced instruments combine optical measurement with gravimetric calibration to provide accurate real-time mass concentration measurements.

Calibration Factors

A critical aspect of aerosol monitoring is the application of appropriate calibration factors. Most aerosol monitors are factory-calibrated using a standard test aerosol, typically Arizona Road Dust or a similar standardized particle suspension.

Theatrical fog has different optical properties than these calibration aerosols. The droplets may be a different size, have different refractive indices, and scatter light differently. This means that the raw readings from an aerosol monitor may not accurately reflect the actual concentration of theatrical fog.

The ANSI standard addresses this by recommending the use of calibration factors specific to theatrical fog fluids. These calibration factors are determined through laboratory testing in which the monitor’s readings are compared to reference measurements under controlled conditions.

Organizations like Ramboll have published calibration factor studies for common theatrical fog fluids. These studies provide the correction factors needed to convert raw monitor readings to accurate concentration values.

Monitoring Locations

Where you place your monitors matters significantly. The standard recommends monitoring in locations where performers and crew will be exposed:

• In the breathing zone of performers (as close to their actual breathing position as practical)
• Near fog machine outputs where concentrations are typically highest
• In enclosed spaces or areas with limited ventilation where fog may accumulate
• At audience level if the fog extends into seating areas

Multiple monitoring points may be necessary to fully characterize exposure conditions throughout a venue.

Documentation

The standard emphasizes the importance of documenting monitoring activities and results. This documentation should include:

• Date, time, and location of monitoring
• Equipment used and calibration status
• Monitoring results, including both raw readings and calibration-corrected values
• Production conditions at the time of monitoring (fog machine settings, ventilation status, etc.)
• Actions taken in response to elevated readings

This documentation serves multiple purposes: it demonstrates compliance with safety standards, provides data for identifying trends or problem areas, and creates a record that can be referenced if health concerns arise.

Decomposition Product Limits

As discussed earlier, the thermal decomposition of fog fluids can produce hazardous byproducts. The ANSI standard addresses this by requiring that concentrations of decomposition products remain below regulatory limits.

The specific limits referenced are the Permissible Exposure Limits (PELs) established by OSHA:

Formaldehyde PEL: 0.75 ppm (8-hour TWA), with a STEL of 2 ppm

Acrolein PEL: 0.1 ppm (8-hour TWA)

Acetaldehyde PEL: 200 ppm (8-hour TWA)

Under normal operating conditions with properly maintained equipment and appropriate fog fluids, concentrations of these decomposition products should remain well below these limits. However, monitoring may be warranted in situations where:

• Equipment malfunctions or operates erratically
• There is evidence of overheating (visible smoke, burning smell, discolored fluid)
• Performers report unusual irritation or symptoms
• Equipment is older or has not been regularly maintained

Monitoring for decomposition products requires different instrumentation than aerosol monitoring. Gas detection tubes, photoionization detectors, or laboratory analysis of air samples may be used depending on the specific compounds of concern.

Equipment Requirements

The ANSI standard includes requirements for fog-generating equipment to minimize hazards:

Temperature Control

Fog machines must maintain operating temperatures within specifications to minimize decomposition. This requires:

• Properly functioning thermostatic controls
• Clean heating elements free from residue buildup
• Appropriate fluid supply to prevent dry firing
• Regular maintenance and inspection

Fluid Compatibility

Fog machines must be used with compatible fluids. Using the wrong fluid can result in:

• Inefficient vaporization and poor fog quality
• Incomplete vaporization leaving residue on heating elements
• Excessive decomposition producing hazardous byproducts
• Equipment damage

Manufacturers typically specify which fluids are compatible with their equipment. These recommendations should be followed.

Maintenance Requirements

The standard emphasizes regular maintenance as essential for safe operation:

• Cleaning of heating elements according to manufacturer recommendations
• Inspection of fluid supply systems for blockages or contamination
• Verification of thermostat function and calibration
• Replacement of worn or damaged components

A maintenance log should be kept documenting all service performed on fog-generating equipment.

Administrative Controls

Beyond equipment requirements, the standard recommends administrative controls to manage exposure:

Pre-Production Planning

Before a production opens, the use of fog effects should be carefully planned:

• Identify all scenes where fog will be used
• Estimate exposure levels and durations
• Plan ventilation and air exchange to manage accumulation
• Establish monitoring protocols
• Develop contingency plans for elevated readings

Communication

All personnel who may be exposed to theatrical fog should be informed:

• Performers should know when fog will be used and what the exposure limits are
• Stage managers should be trained on monitoring protocols and response procedures
• Crew members working in fog-affected areas should understand the hazards
• Medical staff (if present) should be briefed on potential symptoms

Sensitive Individuals

The standard acknowledges that some individuals may be more sensitive to theatrical fog than others. This includes individuals with:

• Asthma or other respiratory conditions
• Allergies or sensitivities to glycols
• Compromised immune systems
• Pregnancy (as a precautionary measure)

Procedures should be in place to identify sensitive individuals and accommodate their needs, which may include limiting their exposure, providing respiratory protection, or modifying effects during their scenes.

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Part Four: ANSI E1.40-2016 In Depth

Understanding Theatrical Dust

While theatrical fog receives more attention, dust effects present their own unique hazards that require careful management. The ANSI E1.40-2016 standard, titled “Recommendations for the Planning of Theatrical Dust Effects,” provides comprehensive guidance for this category of atmospheric effects.

Dust effects are used in theatrical productions to create a variety of visual effects:

• Aged, dusty environments (abandoned buildings, attics, basements)
• Dirty or industrial settings
• Outdoor scenes with visible particulates in the air
• Magical or supernatural effects (sparkling dust, fairy dust, etc.)
• Deterioration or decay effects
• Explosion aftermath or debris simulation

Unlike fog, which is composed of liquid droplets that eventually evaporate, dust consists of solid particles that settle out of the air but remain present on surfaces. This persistence creates both ongoing exposure potential and housekeeping challenges.

Classification of Theatrical Dusts

The ANSI E1.40 standard classifies theatrical dusts into three categories, each with distinct safety considerations:

Category 1: Plant and Animal-Based Dusts

This category includes:

• Flour: Common wheat flour is one of the most frequently used theatrical dusts. It creates a realistic dusty appearance and is readily available.
• Cornstarch: Similar to flour, cornstarch produces a fine, visible dust effect.
• Powdered sugar: Occasionally used for certain visual effects.
• Powdered milk or other dairy products
• Powdered spices or herbs (for scent effects)
• Dried plant materials (crushed leaves, powdered bark, etc.)
• Animal-derived materials (bone meal, powdered horn, etc.)

These materials are generally non-toxic when inhaled in small quantities. However, they present significant hazards:

Combustibility: Many plant-based dusts are highly combustible when dispersed in air. Flour dust explosions have caused numerous industrial disasters. At concentrations between approximately 50 and 60 g/m³, flour forms an explosive mixture with air.

Respiratory irritation: Even non-toxic dusts can cause respiratory irritation, particularly in individuals with allergies or sensitivities.

Allergenic potential: Some individuals may be allergic to specific plant or animal-derived materials.

Category 2: Mineral Dusts

This category includes:

• Silica (silicon dioxide): Found in sand, quartz, and many mineral products. Crystalline silica is a significant respiratory hazard.
• Kaolin (china clay): A clay mineral used in various industrial applications.
• Diatomaceous earth: Composed of fossilized diatoms, this material contains crystalline silica and poses respiratory hazards.
• Calcium carbonate (chalk, limestone dust): Relatively low toxicity but can cause respiratory irritation.
• Gypsum: The primary component of drywall dust.
• Mica: A silicate mineral used for sparkle effects.
• Fuller’s earth: A clay material used historically for cleaning.

Mineral dusts pose serious respiratory hazards:

Silicosis: Chronic inhalation of crystalline silica particles causes silicosis, an incurable lung disease characterized by inflammation and scarring. This is a serious occupational disease that affects workers in mining, construction, and other industries.

Pneumoconiosis: Inhalation of other mineral dusts can cause various forms of pneumoconiosis (dust-related lung disease).

Cancer risk: Some mineral dusts, particularly crystalline silica, are classified as carcinogenic.

The ANSI standard is particularly cautious about mineral dusts, recommending that crystalline silica-containing materials be avoided entirely in theatrical applications due to the severity of the associated health risks.

Category 3: Synthetic Dusts

This category includes:

• Ground plastics: Various plastic materials can be ground to produce dust effects.
• Synthetic fibers: Powdered or chopped synthetic fibers.
• Pigments and dyes: Powdered colorants for colored dust effects.
• Artificial snow products: Many artificial snow products are essentially plastic particles.
• Glitter and reflective particles: While not always considered “dust,” these materials present similar hazards.

Synthetic dusts vary widely in their hazards depending on their chemical composition:

• Some plastics release toxic fumes when heated or burned
• Certain dyes and pigments contain heavy metals or other toxic components
• Many synthetic materials are persistent in the environment and in the body
• Some synthetic materials may be carcinogenic

The standard requires thorough vetting of synthetic materials before use, including review of Safety Data Sheets and assessment of all potential hazards.

Combustibility and Explosion Risks

One of the most critical sections of ANSI E1.40 addresses the risk of dust explosions. This is not a theoretical concern. Dust explosions have caused numerous fatalities in industrial settings, and the same physics apply to theatrical dust.

The Dust Explosion Pentagon

For a dust explosion to occur, five conditions must be present simultaneously:

1. Fuel (combustible dust): A material capable of burning when dispersed in air.
2. Oxidizer (oxygen in air): Normal atmospheric air provides sufficient oxygen.
3. Ignition source: A spark, flame, hot surface, or other energy source capable of igniting the dust.
4. Dispersion (dust cloud): The dust must be suspended in air at sufficient concentration.
5. Confinement: The dust cloud must be at least partially confined for pressure to build.

Remove any one of these five elements, and a dust explosion cannot occur. This provides multiple strategies for prevention.

Explosion Severity Factors

Not all dust explosions are equal in severity. Several factors affect how powerful an explosion will be:

Particle size: Finer particles have more surface area relative to their mass, making them more reactive. Very fine dusts (particles smaller than 75 micrometers) are particularly hazardous.

Concentration: Dust explosions typically occur at concentrations between the Minimum Explosible Concentration (MEC) and the Upper Explosible Limit (UEL). Below the MEC, there is not enough fuel. Above the UEL, there is not enough oxygen between particles.

Moisture content: Wet or damp dust is less explosible than dry dust. Moisture suppresses the reaction.

Chemical composition: Some materials are inherently more reactive than others. Metals like aluminum and magnesium are highly reactive. Organic materials like flour and cornstarch are moderately reactive.

Turbulence: Air movement that keeps dust suspended increases explosion risk. Settled dust is much safer than airborne dust.

Which Theatrical Dusts Are Combustible?

The following common theatrical materials can form explosive mixtures:

Material	MEC (g/m³)	Explosion Severity
Wheat flour	60	High
Cornstarch	45	High
Powdered sugar	45	High
Wood dust	40	High
Coal dust	55	Moderate
Aluminum powder	45	Extreme
Paper dust	35	Moderate
Plastic dust (varies)	25-200	Variable

Any dust effect using these or similar materials must be treated as a potential explosion hazard.

Mitigation Strategies for Explosion Risk

The ANSI E1.40 standard provides detailed guidance for mitigating dust explosion risks:

Eliminating Ignition Sources

In areas where combustible dust will be used:

• No open flames: This includes candles, lighters, pyrotechnic effects, and any other open flame.
• No smoking: Tobacco products and vaping devices must be prohibited.
• Explosion-proof electrical equipment: Standard electrical equipment can produce sparks. Equipment rated for use in combustible dust environments (Class II, Division 1 or 2) should be used.
• Control of hot work: Welding, cutting, grinding, and other hot work must be prohibited during and immediately after dust effects.
• Static electricity control: Static discharge can ignite dust. Grounding, bonding, and humidity control help prevent static buildup.
• Hot surfaces: Equipment that produces heat (lighting fixtures, motors, etc.) must be kept away from dust concentrations.

Controlling Dust Dispersion

Limiting how much dust becomes airborne reduces both explosion and health risks:

• Use the minimum quantity needed: More dust is not always better. Use only what is needed for the desired effect.
• Control application methods: Avoid methods that create large, dense dust clouds.
• Use barriers and containment: Physical barriers can limit how far dust spreads.
• Timing considerations: Brief, controlled releases are safer than prolonged dust generation.

Ventilation

Proper ventilation dilutes dust concentrations below explosive levels:

• General ventilation: Overall air exchange in the space.
• Local exhaust ventilation: Capture of dust at or near its source.
• Avoid recirculation: Filtered makeup air should be used; do not simply recirculate dusty air.
• HVAC considerations: Ensure HVAC systems are designed for dusty environments and will not spread dust throughout the building.

Housekeeping

Accumulated dust represents both an ongoing exposure hazard and a potential source of secondary explosions:

• Regular cleaning: Remove accumulated dust promptly.
• Use appropriate methods: Vacuum with HEPA-filtered, explosion-proof equipment. Do not sweep or blow dust, which simply redistributes it.
• Clean all surfaces: Dust accumulates on horizontal surfaces, ledges, equipment, lighting fixtures, and other areas that may be overlooked.
• Documentation: Maintain records of cleaning activities.

Emergency Preparedness

Despite best efforts, incidents may occur:

• Fire suppression: Appropriate fire suppression systems should be in place.
• Evacuation plans: Everyone should know how to evacuate safely.
• Communication: Clear communication protocols for emergencies.
• First aid: Personnel trained in first aid should be available.

Health Effects of Dust Inhalation

Beyond explosion risks, dust inhalation poses significant health hazards. The ANSI standard provides guidance on protecting workers from these effects.

Acute Effects

Short-term exposure to dust can cause:

• Eye irritation, redness, and tearing
• Nose and throat irritation
• Coughing and sneezing
• Bronchial irritation and chest tightness
• Difficulty breathing, particularly in individuals with respiratory conditions
• Allergic reactions in sensitized individuals

Chronic Effects

Repeated or prolonged exposure can cause:

• Chronic bronchitis
• Occupational asthma
• Pneumoconiosis (dust-related lung disease)
• Silicosis (for crystalline silica exposure)
• Increased risk of respiratory infections
• Potential cancer risk (for certain materials)

Personal Protective Equipment

The standard recommends PPE appropriate to the hazards:

Respiratory Protection

The level of respiratory protection required depends on the type of dust, its concentration, and the exposure duration:

• N95 filtering facepiece respirators: Provide protection against non-oil-based particles. Suitable for low to moderate concentrations of nuisance dusts.
• P100 filtering facepiece respirators: Provide higher efficiency filtration. Required for more hazardous dusts.
• Half-mask air-purifying respirators: With appropriate cartridges, provide better fit and higher protection factors.
• Full-facepiece air-purifying respirators: Provide eye protection in addition to respiratory protection.
• Powered air-purifying respirators (PAPRs): Provide continuous airflow and are more comfortable for extended wear.

For performers, respiratory protection may not be practical during actual performances. This makes engineering and administrative controls even more important.

Eye Protection

Dust can irritate and damage eyes:

• Safety glasses with side shields provide basic protection
• Goggles provide better protection against airborne particles
• Face shields provide splash protection but limited dust protection

Skin Protection

Some dusts can irritate skin:

• Gloves appropriate to the material
• Long sleeves and pants
• Coveralls for heavy dust exposure

Medical Surveillance

For workers regularly exposed to hazardous dusts, medical surveillance may be appropriate:

• Baseline pulmonary function testing
• Periodic follow-up testing
• Medical questionnaires to identify symptoms
• Referral for evaluation of respiratory symptoms

Specific Guidance for Common Effects

The ANSI standard provides specific guidance for common theatrical dust applications:

Fuller’s Earth and Similar Materials

Fuller’s earth has been a traditional theatrical dust material. The standard notes:

• Fuller’s earth may contain crystalline silica, requiring appropriate controls
• Adequate ventilation is essential
• Minimize quantities used
• Thorough cleanup after use

Flour and Food-Grade Materials

While seemingly innocuous, flour and similar materials require:

• Strict ignition source control due to combustibility
• Recognition that “food grade” does not mean “safe to breathe”
• Consideration of allergies (wheat, corn, etc.)
• Proper cleanup to prevent pest attraction

Breakaway Effects

Dust often accompanies breakaway or destruction effects:

• Plan for dust generation during breakaway
• Pre-position ventilation
• Clear the area of unnecessary personnel
• Consider performer protection

Snow Effects

Many artificial snow products are essentially plastic particles:

• Review SDS for specific hazards
• Consider environmental persistence
• Plan for cleanup
• Some products may be slippery when accumulated

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Part Five: Practical Implementation

Building a Safety Program

Understanding the standards is the first step. Implementing them effectively requires building a comprehensive safety program. Here is how to create one:

Policy Development

Begin with written policies that establish:

• The organization’s commitment to atmospheric effects safety
• Roles and responsibilities for safety management
• Compliance requirements (referencing ANSI standards and applicable regulations)
• Consequences for policy violations
• Procedures for addressing concerns

Risk Assessment

Before any production uses atmospheric effects:

1. Identify all planned effects: List every fog, haze, or dust effect planned for the production.
2. Characterize materials: For each effect, document what materials will be used, including specific products and Safety Data Sheet information.
3. Estimate exposures: Determine who will be exposed, for how long, and at what concentrations.
4. Identify hazards: List all potential hazards, including both immediate and long-term risks.
5. Evaluate risks: Assess the likelihood and severity of potential harm.
6. Determine controls: Identify engineering, administrative, and PPE controls needed.
7. Document everything: Create a written risk assessment that can be reviewed and updated.

Control Hierarchy

Apply the hierarchy of controls to manage risks:

1. Elimination: Can the effect be achieved without the hazardous material? Sometimes the answer is yes.
2. Substitution: Can a less hazardous material achieve a similar effect? For example, using glycerin-based fog instead of oil-based.
3. Engineering controls: Can the hazard be controlled through ventilation, containment, or other physical means?
4. Administrative controls: Can procedures, training, and work practices reduce risk?
5. Personal protective equipment: When other controls are insufficient, what PPE is needed?

Training Programs

Everyone who works with or around atmospheric effects needs appropriate training:

Operators and Technicians

• Equipment operation and maintenance
• Hazard recognition
• Monitoring procedures
• Emergency response
• Documentation requirements

Performers

• Potential health effects
• Symptoms to watch for
• How to report concerns
• Accommodations available

Stage Management

• Production requirements and limitations
• Communication protocols
• Response to elevated readings
• Documentation responsibilities

Safety Personnel

• Comprehensive hazard knowledge
• Monitoring expertise
• Regulatory requirements
• Incident investigation

Documentation Requirements

Maintain comprehensive records including:

• Risk assessments for each production
• Safety Data Sheets for all materials used
• Equipment maintenance logs
• Monitoring data and results
• Training records
• Incident reports
• Corrective actions taken

Pre-Production Planning

The time to address atmospheric effects safety is during pre-production, not during tech week. Here is a planning checklist:

Design Phase

• Identify all scenes requiring atmospheric effects
• Determine what effects will achieve the artistic goals
• Select materials that meet safety criteria
• Estimate quantities needed
• Plan for ventilation and air exchange
• Consider performer positions and exposure potential
• Budget for monitoring equipment and supplies

Coordination Meetings

Hold specific meetings to address atmospheric effects:

• Director and designers to confirm artistic intent
• Technical director to address implementation
• Safety personnel to review hazards and controls
• Union representatives (if applicable) to address performer concerns
• Venue management to address facility capabilities

Equipment Selection

Choose equipment that supports safe operation:

• Fog machines with proper temperature controls
• Appropriate fluid for the equipment
• Monitoring instruments with current calibration
• Ventilation equipment sufficient for the application
• PPE for setup, rehearsal, and performance

Scheduling Considerations

Plan the schedule to support safety:

• Allow time for ventilation between heavy fog scenes
• Schedule monitoring during all exposed rehearsals
• Plan for cleaning between rehearsals and performances
• Allow recovery time for performers with heavy exposure scenes

Tech and Dress Rehearsals

The rehearsal period is critical for establishing safe practices:

Initial Technical Rehearsals

• Test all atmospheric effects in isolation before full runs
• Establish baseline fog/haze levels
• Verify monitoring equipment function
• Train operators on equipment settings
• Document settings that achieve desired effects within safety limits

Monitoring During Rehearsals

• Deploy monitors in all relevant locations
• Record readings throughout rehearsals
• Note correlations between effect settings and exposure levels
• Identify problem areas where concentrations exceed limits
• Adjust effects as needed to achieve compliance

Performer Observation

• Watch for signs of irritation or discomfort
• Encourage performers to report symptoms
• Document any complaints
• Make adjustments as needed

Dress Rehearsals

• Run full monitoring protocols as they will operate during performances
• Verify that all effects remain within limits with full cast present
• Make final adjustments
• Confirm that all documentation is in order

Performance Run

During the run of a production:

Pre-Show Checks

• Verify equipment is functioning properly
• Check fluid levels
• Confirm monitor batteries/power
• Review any notes from previous performances

Performance Monitoring

• Deploy monitors at established positions
• Record data at specified intervals
• Watch for any unusual readings
• Be prepared to adjust effects if limits are approached

Post-Show Procedures

• Download and review monitoring data
• Document any issues or concerns
• Clean equipment as needed
• Prepare for next performance

Ongoing Maintenance

• Clean fog machines on manufacturer’s recommended schedule
• Replace fluids as needed
• Calibrate monitors periodically
• Address any equipment issues promptly

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Part Six: Equipment and Technology

Fog Machine Types

Understanding the different types of fog machines helps in selecting appropriate equipment and understanding the hazards involved:

Heated Fog Machines

The most common type. These machines heat fog fluid using an electric heating element (heat exchanger), vaporizing the liquid and producing fog when the vapor contacts cooler air.

Advantages:

• Produce dense, visible fog
• Relatively simple operation
• Wide range of output levels
• Established technology with good reliability

Safety Considerations:

• Temperature must be controlled to prevent decomposition
• Heating elements require regular cleaning
• Fluid must be compatible with machine
• Can produce decomposition products if malfunctioning

Ultrasonic Fog Machines

These machines use high-frequency vibrations to create fog without heating the fluid.

Advantages:

• No thermal decomposition risk
• Cool fog output
• Quiet operation

Safety Considerations:

• May produce smaller particles that penetrate deeper into lungs
• Limited output for large spaces
• Fluid must be specifically formulated for ultrasonic use

Cryogenic Fog Machines

These machines vaporize liquid nitrogen (LN2) or liquid carbon dioxide (CO2) to produce low-lying fog.

Advantages:

• Very dense, dramatic fog
• Stays low to the ground
• No glycol exposure

Safety Considerations:

• Oxygen displacement hazard in enclosed spaces
• Cryogenic liquid handling hazards (severe cold burns)
• High gas volumes require adequate ventilation
• CO2 is an asphyxiant at high concentrations
• Specialized training required

Dry Ice Fog Machines

These machines heat water and introduce solid CO2 (dry ice), which sublimates and produces low-lying fog.

Advantages:

• Dense, low-lying fog
• Dramatic visual effect
• No glycol exposure

Safety Considerations:

• CO2 is an asphyxiant in enclosed spaces
• Dry ice handling hazards (severe cold burns)
• Water heating presents scalding risk
• Less controllable than some other methods

Oil-Based Hazers

Some haze machines use oil-based fluids (often mineral oil) rather than glycol-based fluids.

Advantages:

• Very long hang time
• Creates a persistent haze effect
• Minimal output needed for visible effect

Safety Considerations:

• Oil mist may be more persistent in the body than water-soluble glycols
• Different health considerations than glycol fog
• Not covered by ANSI E1.5 (requires separate risk assessment)
• Can leave residue on surfaces and equipment

Monitoring Equipment

Effective monitoring requires appropriate instrumentation:

Real-Time Aerosol Monitors

Several manufacturers produce monitors suitable for theatrical fog monitoring:

TSI DustTrak Series: These are widely used photometric monitors that provide real-time mass concentration readings. Models range from handheld units to more sophisticated instruments with data logging capabilities.

Thermo Scientific pDR Series: Another line of photometric monitors with various features for different applications.

Casella Microdust Pro: A compact, battery-operated monitor suitable for personal or area monitoring.

When selecting a monitor, consider:

• Detection range (must cover expected concentrations)
• Response time (how quickly readings update)
• Data logging capability (essential for documentation)
• Battery life (sufficient for full performance)
• Calibration requirements and intervals
• Compatibility with theatrical fog (check for available calibration factors)

Calibration

Factory calibration is typically performed using Arizona Road Dust or similar standard material. For accurate theatrical fog measurements, fluid-specific calibration factors must be applied.

Sources for calibration factor data include:

• Fog fluid manufacturer technical bulletins
• Published research studies (Ramboll has published calibration factor studies)
• Laboratory testing services

Monitors should be calibrated on a regular schedule (typically annually) and the calibration verified before each production.

Personal Sampling Equipment

For TWA measurements, personal sampling pumps with gravimetric filters can provide accurate data:

• Pumps draw air through a pre-weighed filter at a measured flow rate
• Filter is weighed after sampling to determine mass collected
• Concentration calculated from mass and total air volume sampled

This method is more accurate than photometric monitoring but provides only time-averaged data, not real-time readings.

Ventilation Systems

Ventilation is critical for managing atmospheric effects:

Types of Ventilation

Natural Ventilation: Air movement through doors, windows, and other openings. Limited control and generally insufficient for managing theatrical fog concentrations.

General Dilution Ventilation: HVAC systems that exchange air throughout a space. Helps reduce average concentrations but may not address localized high concentrations.

Local Exhaust Ventilation (LEV): Systems designed to capture contaminants at or near their source. More effective for controlling localized concentrations but requires careful design.

Theatrical Smoke Extraction Systems: Purpose-built systems designed for theater environments. These may include:

• Floor-level extraction to remove low-lying fog
• Overhead extraction for rising haze
• Variable speed control to adjust extraction rate
• Integration with production requirements (extraction cued to scenic needs)

Design Considerations

When planning ventilation:

• Calculate air exchange rates needed to dilute fog to acceptable levels
• Consider the volume of fog generated and the space volume
• Account for the rise and fall patterns of different fog types
• Plan extraction points based on where fog accumulates
• Ensure makeup air supply is adequate
• Consider noise impacts on production
• Plan for maintenance access

Practical Tips

• Test ventilation during tech before finalizing fog levels
• Establish cue points for ventilation changes
• Monitor to verify ventilation effectiveness
• Have contingency plans for ventilation failures

Fluid Selection

Choosing the right fog fluid matters for both performance and safety:

Compatibility

Always use fluids specified by the fog machine manufacturer. Incompatible fluids may:

• Fail to vaporize properly
• Leave residue on heating elements
• Cause excessive decomposition
• Damage the equipment

Quality

Higher-quality fluids typically:

• Have more consistent composition
• Produce more consistent fog effects
• Minimize decomposition products
• Are manufactured under quality controls that ensure batch-to-batch consistency

Purchase from reputable suppliers and avoid off-brand products of unknown composition.

Safety Data Sheets

Review SDSs for all fog fluids. Key information includes:

• Specific chemical composition
• Health hazard information
• Recommended exposure limits
• First aid measures
• Safe handling practices

Storage

Store fog fluids properly:

• Keep in original containers with labels
• Store at recommended temperatures
• Protect from contamination
• Observe shelf life limitations
• Keep away from ignition sources

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Part Seven: Special Circumstances

Working with Sensitive Individuals

Some individuals are more sensitive to theatrical fog and dust than others. The standards acknowledge this, and production teams must be prepared to accommodate sensitive individuals.

Identifying Sensitive Individuals

People who may be more sensitive include:

• Those with asthma or other respiratory conditions
• Individuals with allergies or sensitivities to glycols or specific dusts
• Those recovering from respiratory illness
• Pregnant individuals (as a precautionary measure)
• Individuals with compromised immune systems
• Older adults, who may have reduced respiratory reserve
• Those with a history of respiratory symptoms from fog exposure

Creating a Disclosure Process

Productions should have a process for identifying sensitive individuals:

• Include questions about respiratory conditions in casting health forms
• Ask about previous experience with theatrical fog
• Provide information about planned atmospheric effects during auditions or hiring
• Create a safe channel for reporting concerns

Accommodation Options

When sensitive individuals are identified:

• Modify effects in scenes where they appear (reduce concentration, duration, or extent)
• Provide respiratory protection during rehearsals (if practical)
• Position performers away from highest concentration areas
• Increase ventilation during their scenes
• Provide breaks from exposure between scenes
• In severe cases, consider casting alternatives

Medical Consultation

For individuals with significant respiratory conditions:

• Encourage consultation with their physician about exposure
• Request physician guidance on safe exposure levels
• Consider independent medical evaluation if concerns persist

Documentation

Document all accommodations:

• What conditions were disclosed
• What accommodations were provided
• How effectiveness was verified
• Any changes made over the production run

This documentation protects both the individual and the organization.

Children and Minors

Productions involving children require extra care:

Physiological Considerations

Children differ from adults in ways that affect exposure:

• Higher respiratory rates relative to body size
• Developing lungs that may be more susceptible to irritation
• Smaller airways that may be more easily obstructed
• Less ability to communicate symptoms clearly
• Limited understanding of risks

Regulatory Requirements

Child labor laws may impose additional requirements:

• Limits on working hours that may affect exposure duration
• Requirements for guardian consent and presence
• Additional safety requirements for youth performers

Practical Recommendations

For productions with children:

• Limit fog concentrations to the lowest levels that achieve the effect
• Minimize children’s time in fog-affected areas
• Position children away from fog sources when possible
• Increase ventilation during children’s scenes
• Monitor more frequently and conservatively
• Train guardians and chaperones on signs of distress
• Have procedures for immediately removing children if symptoms occur

Outdoor Productions

Outdoor venues present different challenges:

Advantages

• Unlimited natural ventilation
• No accumulation in enclosed spaces
• Rapid dispersion of effects

Challenges

• Wind can make fog effects unpredictable
• May require more fog to achieve visible effect
• Weather affects fog behavior
• Less control over exposure conditions

Planning Considerations

• Consider prevailing wind direction in blocking
• Have backup plans for high-wind conditions
• Monitor actual conditions during performance
• Adjust effects based on weather conditions

Film and Television

Film and television productions have unique considerations:

Intense, Short-Term Exposures

Film production often involves:

• Very dense fog for specific shots
• Multiple takes with repeated exposure
• Long shooting days
• Enclosed set environments

Controls for Film Production

• Clear the set of non-essential personnel during heavy fog shots
• Provide respiratory protection for crew members behind camera
• Allow ventilation time between takes
• Monitor continuously during fog use
• Establish clear communication about fog status

Post-Production Documentation

For film productions, maintain records that may be needed years later:

• Fog use on specific shooting days
• Personnel present during exposure
• Monitoring data
• Any reported symptoms

Theme Parks and Continuous Operation

Theme park attractions present unique challenges:

Continuous Operation

Unlike theatrical productions with defined performances:

• Fog may run continuously for hours
• Multiple daily cycles without reset
• Thousands of guests exposed daily
• Operators present for entire shifts

Engineering for Continuous Operation

• Design attractions for adequate ventilation
• Build in redundancy for ventilation systems
• Install permanent monitoring systems
• Automate fog output based on monitoring data
• Design for easy maintenance access

Guest Considerations

• Post warnings about atmospheric effects
• Provide bypass routes for sensitive guests
• Train operators to recognize guest distress
• Have procedures for medical response

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Part Eight: Legal and Regulatory Framework

OSHA Requirements

The Occupational Safety and Health Administration establishes workplace safety requirements that apply to theatrical productions:

General Duty Clause

OSHA’s General Duty Clause requires employers to provide a workplace “free from recognized hazards that are causing or are likely to cause death or serious physical harm.”

Theatrical fog and dust are recognized hazards. Failure to implement appropriate controls could constitute a General Duty Clause violation.

Permissible Exposure Limits

OSHA has established PELs for some substances found in or produced by theatrical fog:

• Propylene glycol: No OSHA PEL (ANSI standards provide guidance)
• Glycerin mist: 15 mg/m³ total, 5 mg/m³ respirable (as particulates not otherwise regulated)
• Formaldehyde: 0.75 ppm TWA, 2 ppm STEL
• Acrolein: 0.1 ppm TWA

For dusts:

• Particles not otherwise regulated: 15 mg/m³ total, 5 mg/m³ respirable
• Crystalline silica: 50 µg/m³ (OSHA’s newer, more protective limit)
• Specific minerals have specific PELs

Respiratory Protection Standard

If respiratory protection is used, OSHA’s Respiratory Protection Standard (29 CFR 1910.134) applies:

• Written respiratory protection program required
• Medical evaluation before respirator use
• Fit testing for tight-fitting respirators
• Training on proper use
• Maintenance and care requirements
• Program administration and record-keeping

Hazard Communication

OSHA’s Hazard Communication Standard requires:

• Safety Data Sheets for hazardous chemicals
• Labels on containers
• Training for exposed workers
• Written hazard communication program

State and Local Regulations

Additional requirements may apply at state and local levels:

State OSHA Programs

Some states operate their own OSHA-approved programs. These programs must be at least as protective as federal OSHA but may have additional or different requirements.

States with their own programs include California (Cal/OSHA), Washington, Oregon, Michigan, and others. Check requirements in your specific state.

Fire Codes

Local fire codes may affect atmospheric effects:

• Permit requirements for certain effects
• Limitations on combustible dust
• Requirements for fire watch
• Coordination with venue fire safety systems

Building Codes

Building codes may affect ventilation requirements:

• Minimum outdoor air rates
• Air quality standards
• Occupancy limitations

Union Agreements

If performers or crew are represented by unions:

• Actors’ Equity Association has specific provisions addressing theatrical fog
• IATSE locals may have provisions affecting crew exposure
• Union safety committees may have approval authority
• Specific notification requirements may apply

Liability Considerations

Understanding liability helps motivate proper safety practices:

Workers’ Compensation

Employees who develop health conditions from workplace exposure may file workers’ compensation claims:

• Medical expenses covered
• Lost wages compensated
• Permanent disability benefits possible
• Employers pay through insurance or self-insurance

Third-Party Lawsuits

Non-employees (including audience members and some performers) may be able to sue:

• Negligence claims alleging failure to exercise reasonable care
• Product liability claims against fog fluid or equipment manufacturers
• Premises liability claims against venue owners

Documentation as Protection

Comprehensive documentation helps defend against claims:

• Demonstrates compliance with standards
• Shows reasonable care was exercised
• Provides evidence of actual exposure levels
• Documents training and communication

Insurance Considerations

Insurance coverage should be verified:

• General liability policies may have pollution exclusions
• Coverage for gradual contamination versus sudden events
• Adequacy of limits for potential claims
• Notice requirements for claims or potential claims

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Part Nine: Emergency Response

Recognizing Problems

The first step in emergency response is recognizing that a problem exists:

Signs of Overexposure (Individual)

• Excessive coughing, throat irritation
• Eye watering, redness, irritation
• Difficulty breathing, wheezing
• Chest tightness
• Headache, dizziness
• Nausea
• Skin irritation

Signs of Equipment Malfunction

• Unusual odor (burning, chemical smell)
• Visible smoke (as distinct from fog)
• Unusual sounds from equipment
• Erratic output
• Discoloration of fluid or output

Signs of Dangerous Conditions (Dust)

• Visible dust cloud density increasing
• Accumulation on surfaces
• Reduced visibility
• Reports of ignition source proximity

Response Procedures

Have documented procedures for various scenarios:

Individual Experiencing Symptoms

1. Remove the individual from the exposure area
2. Move to fresh air
3. If breathing difficulty is severe, call emergency medical services
4. If symptoms persist, seek medical evaluation
5. Document the incident

Equipment Malfunction

1. Shut down the malfunctioning equipment immediately
2. Increase ventilation to clear any contaminated air
3. Evacuate the immediate area if smoke or unusual odors persist
4. Do not restart until the equipment is inspected and repaired
5. Document the incident

Elevated Monitoring Readings

1. Reduce or stop fog output
2. Increase ventilation
3. Verify that readings decrease
4. Investigate the cause of the elevated reading
5. Adjust procedures to prevent recurrence
6. Document the incident

Dust Fire or Explosion

1. Activate fire alarm and evacuation
2. Call emergency services
3. Do not attempt to fight a dust fire unless trained and equipped
4. Account for all personnel
5. Do not re-enter until cleared by authorities
6. Document the incident

Post-Incident Procedures

After any incident:

Immediate Actions

• Ensure all affected individuals receive appropriate medical care
• Secure the scene to preserve evidence
• Notify appropriate authorities (OSHA for serious injuries)
• Notify insurance carriers as required
• Document everything while memories are fresh

Investigation

• Determine what happened
• Identify root causes
• Assess whether procedures were followed
• Identify what could have prevented the incident
• Develop corrective actions

Corrective Actions

• Implement changes to prevent recurrence
• Update procedures as needed
• Provide additional training
• Modify equipment or facilities as needed
• Verify effectiveness of changes

Documentation

Maintain complete incident records including:

• Date, time, location
• Individuals involved
• Description of what happened
• Investigation findings
• Corrective actions taken
• Follow-up activities

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Part Ten: Building a Culture of Safety

Leadership Commitment

Safety culture starts at the top:

Visible Commitment

Leaders must demonstrate that safety matters:

• Attend safety meetings
• Allocate resources for safety
• Hold people accountable for safety performance
• Never pressure workers to take unsafe shortcuts
• Recognize and reward safe behavior

Policy Support

Leaders must support safety policies:

• Enforce policies consistently
• Resist pressure to compromise safety
• Back up workers who raise concerns
• Provide time and resources for training

Resource Allocation

Safety requires resources:

• Budget for monitoring equipment
• Budget for training
• Budget for maintenance
• Budget for safety staffing

Communication

Effective communication enables safety:

Pre-Production Communication

• Include safety in design discussions
• Communicate hazards early
• Solicit input from all affected parties
• Address concerns before they become problems

Rehearsal Communication

• Conduct safety briefings
• Explain what effects will be used
• Describe monitoring protocols
• Explain how to report concerns

Performance Communication

• Pre-show safety checks
• Clear communication channels for safety issues
• Post-show debriefs to address concerns

Ongoing Communication

• Regular safety meetings
• Updates on changes or issues
• Recognition of good safety performance
• Open channels for concerns

Training

Training is essential at all levels:

Initial Training

All personnel should receive training on:

• Hazards of atmospheric effects
• Control measures in use
• How to recognize symptoms
• How to report concerns
• Emergency procedures

Refresher Training

Periodic refresher training maintains awareness:

• Review of key concepts
• Updates on any changes
• Discussion of recent issues or incidents
• Reinforcement of key behaviors

Specialized Training

Some personnel need specialized training:

• Equipment operators
• Monitoring personnel
• Safety coordinators
• Emergency responders

Documentation

Maintain training records including:

• Who was trained
• When training occurred
• What topics were covered
• Verification of understanding

Continuous Improvement

Safety programs should continuously improve:

Performance Monitoring

Track safety performance metrics:

• Monitoring results over time
• Number of elevated readings
• Reports of symptoms
• Equipment maintenance compliance
• Training completion rates

Trend Analysis

Look for patterns:

• Recurring problems
• Equipment reliability issues
• Training gaps
• Systemic factors

Benchmarking

Learn from others:

• Industry best practices
• Published research
• Professional organization guidance
• Peer organization experiences

Program Review

Periodically review the overall program:

• Annual comprehensive review
• Assessment against standards
• Gap analysis
• Improvement planning

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Part Eleven: Looking Forward

Emerging Technologies

The technology of atmospheric effects continues to evolve:

Low-Emission Fog Systems

Manufacturers are developing fog systems designed to minimize exposure:

• More efficient vaporization reducing fluid consumption
• Better temperature control preventing decomposition
• Smaller droplet sizes for equivalent visual effect with lower mass concentration
• Recirculating systems that filter and reuse fog

Alternative Materials

Research into alternative fog materials continues:

• Water-based systems using purified water alone
• Bio-based fluids with different safety profiles
• Materials designed for specific visual effects with minimal health impact

Improved Monitoring

Monitoring technology is advancing:

• Smaller, less expensive monitors enabling more comprehensive monitoring
• Wireless monitors enabling real-time data collection
• Integration with automated control systems
• Personal exposure monitoring for individual performers

Automation and Control

Integration of monitoring and control systems:

• Automated fog output adjustment based on monitoring data
• Predictive systems that anticipate concentration buildups
• Integration with ventilation systems for coordinated control
• Documentation systems that automatically record compliance data

Evolving Standards

The ANSI standards will continue to evolve:

Research Advances

Ongoing research will inform future standards:

• Better understanding of health effects
• Improved exposure assessment methods
• New materials requiring new guidance

Industry Experience

Experience implementing current standards will identify:

• Areas where guidance is unclear
• Practical challenges requiring solutions
• Opportunities for improvement

Regulatory Changes

Changes in OSHA or other regulatory requirements may affect:

• Exposure limits
• Monitoring requirements
• Documentation requirements
• Enforcement priorities

Preparing for the Future

Productions can prepare for evolving requirements:

• Stay current on standards developments
• Participate in industry discussions
• Invest in monitoring and documentation systems that can adapt
• Build a culture of safety that values continuous improvement
• Document current practices to demonstrate good faith efforts

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Conclusion: Making Safety Part of Your DNA

We started this guide with a vision: creating those magical moments when fog transforms a stage into something extraordinary. We end with a commitment: ensuring that this magic never comes at the cost of anyone’s health or safety.

The ANSI standards for theatrical fog and dust are not obstacles to creativity. They are not bureaucratic hurdles to be overcome. They are tools that enable you to push creative boundaries responsibly. They represent decades of research, expert deliberation, and hard-won lessons that help you protect everyone who walks onto your stage.

Here is what I want you to take away from this guide:

The risks are real. Theatrical fog and dust are not just aesthetic choices. They are potential health hazards that require serious attention. Ignoring these risks exposes performers, crew, and your organization to harm.

The solutions are achievable. Implementing proper safety protocols is not prohibitively expensive or complicated. With appropriate planning, monitoring, and controls, you can create stunning effects while protecting everyone involved.

Documentation matters. Comprehensive records of your safety practices protect both your people and your organization. They demonstrate due diligence and provide a foundation for continuous improvement.

Culture is key. Technical compliance is necessary but not sufficient. Building a culture where everyone values safety, communicates openly, and continuously improves makes the difference between a program on paper and true protection.

The standards are your allies. ANSI E1.5 and ANSI E1.40 provide clear, science-based guidance that takes the guesswork out of safety decisions. Use them as the foundation for your program.

Your performers trust you with their wellbeing. Your crew trusts you with their safety. Your audience trusts that the experience you create is one they can enjoy without risk. Honor that trust by making these standards part of your production DNA.

The fog will still look magical. The dust will still create atmosphere. And everyone goes home healthy.

That is the real transformation.

Now go create something extraordinary, and do it safely.

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Occupational Safety and Health Administration. (2016). Occupational exposure to respirable crystalline silica; final rule. 81 FR 16285.

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Ramboll. (2023). Theatrical smoke, fog, and haze testing: Calibration factors. Technical Report.

Rodenburg, N., Blanc, P. D., & Balmes, J. R. (2019). Occupational and environmental health effects of fog and haze. Annals of the American Thoracic Society, 16(7), 860-867.

Schenker, M. B., Christiani, D., Cormier, Y., Dimich-Ward, H., Doekes, G., Dosman, J., … & Wagner, G. (1998). Respiratory health hazards in agriculture. American Journal of Respiratory and Critical Care Medicine, 158(5), S52-S64.

Teschke, K., Chow, Y., Beaulne, P. D., Brauer, M., van Netten, C., Kennedy, S. M., & Deering, K. (2000). Exposures to atmospheric effects in film and television production. AIHA Journal, 61(3), 342-350.

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Appendix A: Implementation Checklists

Pre-Production Checklist

Planning Phase

• [ ] Identify all planned atmospheric effects
• [ ] Document materials to be used
• [ ] Obtain Safety Data Sheets for all materials
• [ ] Complete risk assessment
• [ ] Identify required controls
• [ ] Budget for safety requirements
• [ ] Assign safety responsibilities

Equipment Phase

• [ ] Select appropriate fog machines
• [ ] Verify fluid compatibility
• [ ] Obtain monitoring equipment
• [ ] Verify calibration status
• [ ] Obtain PPE as needed
• [ ] Verify ventilation capabilities
• [ ] Test emergency systems

Communication Phase

• [ ] Brief design team on safety requirements
• [ ] Notify performers of planned effects
• [ ] Conduct pre-production safety meeting
• [ ] Document sensitive individuals
• [ ] Plan accommodations as needed
• [ ] Establish reporting channels

Technical Rehearsal Checklist

Equipment Setup

• [ ] Install fog machines per design
• [ ] Verify equipment function
• [ ] Set initial operating parameters
• [ ] Position monitors appropriately
• [ ] Verify ventilation function
• [ ] Test communication systems

Initial Testing

• [ ] Test effects in isolation
• [ ] Establish baseline readings
• [ ] Document settings
• [ ] Adjust as needed for safety

Full Run-Throughs

• [ ] Monitor throughout rehearsals
• [ ] Record all data
• [ ] Document any issues
• [ ] Adjust settings as needed
• [ ] Verify compliance with limits

Performer Observation

• [ ] Brief performers on effects
• [ ] Watch for symptoms
• [ ] Document any complaints
• [ ] Make adjustments as needed

Performance Checklist

Pre-Show

• [ ] Check equipment function
• [ ] Verify fluid levels
• [ ] Check monitor battery/power
• [ ] Review any notes from prior performance
• [ ] Brief any new personnel

During Performance

• [ ] Deploy monitors at positions
• [ ] Record readings at intervals
• [ ] Watch for elevated readings
• [ ] Be prepared to adjust

Post-Show

• [ ] Download monitoring data
• [ ] Document any issues
• [ ] Clean equipment as scheduled
• [ ] Prepare for next performance

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Appendix B: Monitoring Record Template

Production: _________________________ Date: _____________

Venue: _____________________________ Show Number: _______

Monitor Make/Model: _________________ Serial Number: _______

Calibration Date: ____________________ Calibration Factor: _____

Fog Fluid Used: _____________________ SDS on File: □ Yes □ No

Time	Location	Raw Reading (mg/m³)	Corrected Reading	Notes

Average Concentration: _______________ mg/m³

Peak Concentration: __________________ mg/m³

Duration of Exposure: _______________ hours

TWA Calculation: ___________________ mg/m³

Compliance Status: □ Within Limits □ Elevated □ Exceeded

Actions Taken (if any): _______________________________________

Recorded By: ______________________ Date: ______________

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Appendix C: Incident Report Template

Date of Incident: _______________ Time: _______________

Location: __________________________________________________

Production: ________________________________________________

Persons Involved: ___________________________________________

Description of Incident:

---

---

---

Immediate Actions Taken:

---

---

Medical Attention Provided: □ None □ First Aid □ Emergency Services

Equipment Involved: _________________________________________

Monitoring Data at Time of Incident: __________________________

Witnesses: _________________________________________________

Root Cause Analysis:

---

---

Corrective Actions:

---

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Follow-Up Required: □ Yes □ No

Follow-Up Completed: _____________ (date)

Reported By: ______________________ Date: ______________

Reviewed By: ______________________ Date: ______________

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Appendix D: Glossary of Terms

Aerosol: A suspension of fine solid particles or liquid droplets in a gas.

ANSI: American National Standards Institute, a private non-profit organization that oversees the development of voluntary consensus standards in the United States.

Calibration Factor: A multiplier applied to raw monitor readings to correct for differences between the calibration aerosol and the actual aerosol being measured.

Decomposition Products: Chemicals formed when a substance breaks down due to heat, light, or other factors.

Dihydric Alcohol: An organic compound containing two hydroxyl (OH) groups, such as propylene glycol.

Dust Explosion: A rapid combustion of fine particles suspended in air within an enclosed space, resulting in a rapid increase in pressure.

Glycerin (Glycerol): A trihydric alcohol commonly used in fog fluids.

Gravimetric Sampling: A method of measuring particle concentration by collecting particles on a filter and weighing the filter.

Haze: A very fine, persistent atmospheric effect that makes light beams visible without significantly reducing visibility.

LEV (Local Exhaust Ventilation): A system designed to capture contaminants at or near their source.

MEC (Minimum Explosible Concentration): The lowest concentration of dust in air at which an explosion can occur.

PEL (Permissible Exposure Limit): The maximum amount or concentration of a chemical to which a worker may be exposed, as established by OSHA.

Photometric Monitor: An instrument that measures particle concentration based on light scattering.

PPE (Personal Protective Equipment): Equipment worn to minimize exposure to hazards, including respiratory protection, eye protection, and protective clothing.

Propylene Glycol: A dihydric alcohol commonly used as the primary component in theatrical fog fluids.

Respirable Fraction: Particles small enough to penetrate into the gas-exchange region of the lungs.

SDS (Safety Data Sheet): A document providing information about a chemical product, including hazards, safe handling, and emergency procedures.

STEL (Short-Term Exposure Limit): The maximum concentration to which workers can be exposed for a short period (typically 15 minutes) without adverse effects.

Thermal Decomposition: The breakdown of a substance due to heat.

Trihydric Alcohol: An organic compound containing three hydroxyl (OH) groups, such as glycerin.

TWA (Time-Weighted Average): The average concentration of a substance over a specified time period, typically eight hours.

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