Theatrical smoke and fog
The use of fogs can be found throughout motion picture and television productions, live theatre, concerts, at nightclubs and raves, amusement and theme parks and even in video arcades and similar venues.
Common popular applications for theatrical fog include environmental testing (such as HVAC inspections) as well as emergency personnel and disaster response training exercises.
Militaries have historically used smoke and fog to mask troop movements in training and combat, the techniques of which are technologically similar to those used in theatre and film.
This effect can be used for a variety of applications, including simulating geysers of steam, in place of pyrotechnics, or to create an instant opaque wall for a reveal or disappearance during magic acts.
Because carbon dioxide cannot exist as a liquid at atmospheric pressure, the dry ice sublimates and instantly produces a gas,[2] condensing water vapour and creating a thick white fog.
These types of machines are commonly referred to as "dry foggers" because the fog created by this method consists solely of water droplets, and as it dissipates there is little to no residue left on any surfaces.
Smoke machines are commonly used in the testing of larger HVAC systems to identify leaks in ducting, as well as to visualize air flow.
The operating characteristics of this compact, well-engineered and remote-controllable package make possible a range of safe special effects that would be totally impractical with larger, more conventional fog units.
[10]Unsafe concentrations of carbon dioxide can cause headaches, nausea, blurred vision, dizziness and shortness of breath.
When using compressed carbon dioxide or dry ice, care should be taken to ensure there is sufficient ventilation available at all times, and that procedures are in place to rapidly evacuate CO2 from any enclosed space in an emergency.
Liquid carbon dioxide, (5 atmospheres; −56.6 °C), stored in compressed cylinders, also presents all the hazards attendant to materials under pressure and should be handled accordingly.
A number of studies have been published on the potential health effects presented by exposure to theatrical fogs and artificial mists.
The findings of the Consultech study were confirmed by two additional studies—a Health Hazard Evaluation completed in 1994 by the National Institute for Occupational Safety and Health,[11] and another one in 2000 by the Department of Community and Preventative Medicine at the Mount Sinai School of Medicine and ENVIRON;[12] both prepared for Actors Equity and the League of American Theatres and Producers, focused on the effects on actors and performers in Broadway musicals.
The conclusion of all three studies was that there was irritation of mucous membranes such as the eyes and the respiratory tract associated with extended peak exposure to theatrical fog.
Exposure guidelines were outlined in the 2000 study that, it was determined, should prevent actors from suffering adverse impact to their health or vocal abilities.
Another study[13] focused on the use of theatrical fog in the commercial aviation industry for emergency training of staff in simulated fire conditions.
In May 2005, a study published in the American Journal of Industrial Medicine,[14] conducted by the School of Environment and Health at the University of British Columbia, looked at adverse respiratory effects in crew members on a wide variety of entertainment venues ranging from live theatres, concerts, television and film productions to a video arcade.
This study determined that cumulative exposure to mineral oil and glycol-based fogs was associated with acute and chronic adverse effects on respiratory health.
This study found that short-term exposure to glycol fog was associated with coughing, dry throat, headaches, dizziness, drowsiness, and tiredness.
