Frequently Asked Questions about Theatrical Fog 

Is glycol/water-based theatrical fog actually "smoke"?

No. Smoke is made up of solid particles that are a by-product of combustion. Glycol/water fogs are not burned, they are vaporized similar to boiling water. They become pure liquid micro-droplets that leave no residue when evaporated. 

What are the industry guidelines regarding fog/haze use?

The Industry Wide Labor-Management Safety Committee has researched and published 

Safety Bulletin 10 & 10A

regarding the use of artificially created atmospheric fog & haze. It provides current guidelines,  standard practices, and contains well-researched scientifically-driven safety information. For example, it recommends notifying the cast and crew in advance of the scheduled fog or haze use. Attaching this bulletin to the call sheet is an informative way to communicate that notice.

The SAG-AFTRA Blue Ribbon Commission has also assembled an outline of points you should know when working around artificial fog and haze. It speaks to all forms of "smoke" in general; and not specifically glycol-based options. It describes some of your rights along with resources to whom you can voice your concerns.

Blue Ribbon Commission on Safety

Artificial Smoke, Fog and Haze

How do I know what is in the fog fluid?

Safety Data Sheets (SDS) are typically available from the special effects department operating the fog/haze equipment. A review of this document should indicate the contents of the fluid.

Fog Fluid SDS Page

There are six industry accepted glycols: triethylene, propylene, dipropylene, polyethylene, 1,2- butylene, and 1,3-butylene. Glycols to avoid are ethylene, diethylene, and 1,4-butylene. The table linked HERE outlines the contents of many fluids.

What other products contain glycols?

Due to the safety profiles of these glycols, they can be found in many consumer products. including soaps, shampoos, eye drops, asthma inhalers, nebulizers, air sanitizer mists, personal lubricants, oral medication, children's suppositories, and much more.

Is it harmful to children?

The EPA has determined that “There are no indications of special sensitivity of infants or children resulting from exposure to triethylene glycol (TEG). …The Agency has no risk concerns for triethylene glycol with respect to human exposure.” - EPA Reregistration Eligibility Decision

In the 2013 review, the EPA merged propylene glycol (PG) and dipropylene glycol (DPG) into the TEG decision review due to their similar use patterns, comparable chemistry and characteristics, and low toxicity.

Are there exposure limitations?

Although OSHA does not specifically regulate TEG and PG, The Entertainment Services and Technology Association (ESTA) and The American National Standards Institute (ANSI) 

recommend exposure limits of:

10mg per cubic meter (light to moderate haze)

8-hr average exposure time

40mg per cubic meter (heavy haze)

peak exposure limit

These limits have an enormous safety factor baked in. According to the EPA, mammalian tests "showed a lack of systemic toxicity at doses in excess of 1000mg per cubic meter. Chronic exposure of experimental animals to TEG at doses equivalent to or in excess of that dose for such studies has shown the chemical to be without adverse toxic effects." 

What symptoms can occur from excessive exposure?

Glycols attract and absorb water. Although not dangerous, heavy or prolonged exposure can cause temporary dry mouth and eyes, easily remedied by drinking water. In rare cases, some people with heightened sensitivities can experience itchy eyes and irritated sinuses. Again, this effect is temporary with no permanent harmful effects and is quickly remedied by moving into fresh air.

Is glycerin fog and haze the same as glycol fog and haze?

Although glycerin is also non-toxic and possesses chemical similarities to glycol, studies have indicated it doesn't have the same lethal effect on airborne microbes.

How safe are mineral oil fogs and hazes?

Highly refined mineral oils have a history of safe use at low levels, and are regulated by OSHA due to their prevalence in machine shops. The important factor is that it's "highly refined", meaning any impurities which can be toxic have been removed. Excessive exposure to mineral oils swallowed orally can result in the temporary symptom of diarrhea. The nature of mineral oil's interactions with airborne microbes and pathogens is currently unknown.

How safe are non-liquid fog options?

Other choices for fog effects have included olibanum, smoke cookies, and smoke pellets. All of these produce solid smoke particles and do indeed present toxicity concerns. As in the use of cigarettes on set, these items should be used sparingly to minimize exposure, especially around children. Their interactions with microbes and pathogens are currently unknown.

How safe are cryo-fogs?

The most common cryo-fogs we use are produced using Carbon Dioxide (CO2) or Liquid Nitrogen, both common airborne gases. Large quantities dispersed over time can alter the the normal airborne gas ratios of Oxygen/Nitrogen/CO2, and must be supervised by a trained technician. Periodic ventilation practices must be observed, and people's interaction with it monitored.  Being heavier than air, cryo-fogs are often used to make beautiful, low-lying floor-fog effects that displace the low-lying oxygen, necessitating proper care to insure no people are lying in it and thus suffocating. There is one cryogenic option that allows actors to safely lie within it - Liquid Air. It's a bit more expensive and usually sold by the tanker truckload.

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