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Theatrical smoke and fog, also known as special effect smoke, fog or haze, is a category of atmospheric effects used in the entertainment industry. 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. These atmospheric effects are used for creating special effects, to make lighting and lighting effects visible, and to create a specific sense of mood or atmosphere. Recently smaller, cheaper fog machines have become available to the general public, and fog effects are becoming more common in residential applications, from small house parties to
Halloween Halloween or Hallowe'en (less commonly known as Allhalloween, All Hallows' Eve, or All Saints' Eve) is a celebration observed in many countries on 31 October, the eve of the Western Christian feast of All Saints' Day. It begins the observanc ...
and Christmas. Theatrical fog and theatrical fog machines are also becoming more prevalent in industrial applications outside of the entertainment industry, due to their ease of use, inherent portability and ruggedness. Common popular applications for theatrical fog include environmental testing (such as
HVAC Heating, ventilation, and air conditioning (HVAC) is the use of various technologies to control the temperature, humidity, and purity of the air in an enclosed space. Its goal is to provide thermal comfort and acceptable indoor air quality. HV ...
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.


Types of effects

There are generally 4 types of fog effects used in entertainment applications: smoke, fog, haze, and "low-lying" effects.


Smoke

Smoke effects refers to theatrical atmospheric effects produced either by
pyrotechnic Pyrotechnics is the science and craft of creating such things as fireworks, safety matches, oxygen candles, explosive bolts and other fasteners, parts of automotive airbags, as well as gas-pressure blasting in mining, quarrying, and demolition. ...
materials, such as Smoke Cookies, and pre-fabricated smoke cartridges; or other,
flammable A combustible material is something that can burn (i.e., ''combust'') in air. A combustible material is flammable if it ignites easily at ambient temperatures. In other words, a combustible material ignites with some effort and a flammable mat ...
substances such as
incense Incense is aromatic biotic material that releases fragrant smoke when burnt. The term is used for either the material or the aroma. Incense is used for aesthetic reasons, religious worship, aromatherapy, meditation, and ceremony. It may also be ...
or
HVAC Heating, ventilation, and air conditioning (HVAC) is the use of various technologies to control the temperature, humidity, and purity of the air in an enclosed space. Its goal is to provide thermal comfort and acceptable indoor air quality. HV ...
smoke pencils or pens. Smoke is differentiated from other atmospheric effects in that it is composed of solid particles released during combustion, rather than the liquid droplets that fog or haze are composed of.


Fog

Fog is created by pumping one of a variety of different
glycol A diol is a chemical compound containing two hydroxyl groups ( groups). An Aliphatic compound, aliphatic diol is also called a glycol. This pairing of functional groups is pervasive, and many subcategories have been identified. The most common ...
or glycol/water mixtures (referred to as fog fluid) into a heat exchanger (essentially a block of metal with a resistance heating element in it) and heating until the fluid vapourises, creating a thick
translucent In the field of optics, transparency (also called pellucidity or diaphaneity) is the physical property of allowing light to pass through the material without appreciable scattering of light. On a macroscopic scale (one in which the dimensions a ...
or
opaque Opacity or opaque may refer to: * Impediments to (especially, visible) light: ** Opacities, absorption coefficients ** Opacity (optics), property or degree of blocking the transmission of light * Metaphors derived from literal optics: ** In lingu ...
cloud. Devices specifically manufactured for this purpose are referred to as fog machines. An obsolete method for creating theatrical fog on-stage (although the technique is still used in motion pictures) is to use a device known as a thermal fogger, initially designed for distributing pesticide, which aspirates a petroleum product (typically
kerosene Kerosene, paraffin, or lamp oil is a combustible hydrocarbon liquid which is derived from petroleum. It is widely used as a fuel in aviation as well as households. Its name derives from el, κηρός (''keros'') meaning "wax", and was regi ...
or
propane Propane () is a three-carbon alkane with the molecular formula . It is a gas at standard temperature and pressure, but compressible to a transportable liquid. A by-product of natural gas processing and petroleum refining, it is commonly used a ...
), ignites the fuel to create a flame, and then heats a mixture of air and pesticide to create a dense fog. This technique is similar to the smoke generators used by military forces to create
smoke screens A smoke screen is smoke released to mask the movement or location of military units such as infantry, tanks, aircraft, or ships. Smoke screens are commonly deployed either by a canister (such as a grenade) or generated by a vehicle (such as ...
, and is generally only used outdoors due to the volume of fog produced and the petroleum fuel required. For theatrical purposes the pesticide is typically replaced with glycol, glycol/water mixtures, or water. "Low-lying" fog effects can be created by combining a fog machine with another device designed specifically for this purpose. As the fog exits the fog machine it is chilled, either by passing through a device containing a fan and ice, or by passing through a device containing a fan and
compressor A compressor is a mechanical device that increases the pressure of a gas by reducing its volume. An air compressor is a specific type of gas compressor. Compressors are similar to pumps: both increase the pressure on a fluid and both can transp ...
similar to an
air conditioner Air conditioning, often abbreviated as A/C or AC, is the process of removing heat from an enclosed space to achieve a more comfortable interior environment (sometimes referred to as 'comfort cooling') and in some cases also strictly controlling ...
. The result is a relatively thick fog that stays within a few feet of the ground. As the fog warms, or is agitated, it rises and dissipates. Several manufacturers of theatrical fog fluid have developed specially formulated mixtures specifically designed to be used with , intended to provide thicker, more consistent fog effects. Although these chilling devices do not use carbon dioxide, the specially formulated fog fluid does create denser fog than regular fog fluid.


Haze

Haze effects refer to creating an unobtrusive,
homogeneous Homogeneity and heterogeneity are concepts often used in the sciences and statistics relating to the uniformity of a substance or organism. A material or image that is homogeneous is uniform in composition or character (i.e. color, shape, siz ...
cloud intended primarily to reveal lighting beams, such as "light fingers" in a rock concert. This effect is produced using a
haze machine Haze machines, or haze generators (commonly referred to as hazers), are effects machines similar to fog machines, designed to produce an unobtrusive, homogeneous clouds suspended in the air intended primarily to make light beams visible or create ...
, typically done in one of two ways. One technique uses
mineral oil Mineral oil is any of various colorless, odorless, light mixtures of higher alkanes from a mineral source, particularly a distillate of petroleum, as distinct from usually edible vegetable oils. The name 'mineral oil' by itself is imprecise, ...
, atomized via a spray pump powered either by electricity or compressed CO2, breaking the mineral oil into a fine mist. Another technique for creating haze uses a glycol/water mixture to create haze in a process nearly identical to that for creating fog effects. In either case the fluid used is referred to as haze fluid, but the different formulations are not compatible or interchangeable. Glycol/water haze fluid is sometimes referred to as "water based haze" to avoid
ambiguity Ambiguity is the type of meaning in which a phrase, statement or resolution is not explicitly defined, making several interpretations plausible. A common aspect of ambiguity is uncertainty. It is thus an attribute of any idea or statement ...
. Smaller volumes of haze can also be generated from
aerosol An aerosol is a suspension (chemistry), suspension of fine solid particles or liquid Drop (liquid), droplets in air or another gas. Aerosols can be natural or Human impact on the environment, anthropogenic. Examples of natural aerosols are fog o ...
canisters containing mineral oil under pressure. Although the density of haze generated and the volume of space that can be filled is significantly smaller than that of a haze machine, aerosol canisters have the advantages of portability, no requirements for electricity and finer control over the volume of haze generated.


Carbon dioxide and dry ice

Liquid carbon dioxide Liquid carbon dioxide is the liquid state of carbon dioxide (), which cannot occur under atmospheric pressure. It can only exist at a pressure above , under (temperature of critical point) and above (temperature of triple point). Low-temperatu ...
(CO2), stored in compressed cylinders, is used in conjunction with theatrical fog machines to produce "low-lying" fog effects. When liquid CO2 is used to chill theatrical fog, the result is a thick fog that stays within a few feet of the ground. As the fog warms, or is agitated, it rises and dissipates. Several manufacturers of theatrical fog fluid have developed specially formulated mixtures specifically designed to be used with CO2, intended to provide thicker, more consistent fog effects. Effect duration is determined by the heating cycle of the theatrical fog machine and consumption rate of liquid CO2. A large billowing
fog Fog is a visible aerosol consisting of tiny water droplets or ice crystals suspended in the air at or near the Earth's surface. Reprint from Fog can be considered a type of low-lying cloud usually resembling stratus, and is heavily influ ...
plumes are created from the
condensation Condensation is the change of the state of matter from the gas phase into the liquid phase, and is the reverse of vaporization. The word most often refers to the water cycle. It can also be defined as the change in the state of water vapor to ...
of liquid that dry ice is submerged into. As dry ice is submerged into a bulk of liquid, the pure CO2 gas bubbles are formed, then the bulk liquid molecules start to evaporate at the surface of the bubbles into the gas bubbles. The evaporated liquid molecules are later condensed within the bubbles creating a fog which lead to more evaporation of liquid molecules into gas bubbles based on LeChatelier ’s principle. The fog is released through an electric
solenoid valve A solenoid valve is an electromechanically operated valve. Solenoid valves differ in the characteristics of the electric current they use, the strength of the magnetic field they generate, the mechanism they use to regulate the fluid, and the ty ...
to control timing and duration. When the solenoid valve is closed, the fog rapidly disperses in the air, ending the effect nearly instantaneously. This effect can be used for a variety of applications, including simulating
geysers A geyser (, ) is a spring characterized by an intermittent discharge of water ejected turbulently and accompanied by steam. As a fairly rare phenomenon, the formation of geysers is due to particular hydrogeological conditions that exist only in ...
of steam, in place of
pyrotechnics Pyrotechnics is the science and craft of creating such things as fireworks, safety matches, oxygen candles, explosive bolts and other fasteners, parts of automotive airbags, as well as gas-pressure blasting in mining, quarrying, and demolition. ...
, or to create an instant opaque wall for a reveal or disappearance during magic acts.
Dry ice Dry ice is the solid form of carbon dioxide. It is commonly used for temporary refrigeration as CO2 does not have a liquid state at normal atmospheric pressure and sublimates directly from the solid state to the gas state. It is used primarily a ...
(solid carbon dioxide) effects are produced by heating water to or near boiling in a suitable container (for example: a 55-gallon drum with water heater coils in it), and then dropping in one or more pieces of dry ice. Because carbon dioxide cannot exist as a liquid at atmospheric pressure, the dry ice sublimates and instantly produces a gas, condensing water vapour and creating a thick white fog. A fan placed at the top of the container directs the fog where it is needed, creating a rolling fog that lies low to the ground. As the submerged dry ice cools the water, the amount and duration of fog produced will be reduced, requiring "rest" periods to reheat the water. Dry ice can also be used in conjunction with a fog machine to create a low-lying fog effect. Dry ice is placed inside an insulated container with an
orifice An orifice is any opening, mouth, hole or vent, as in a pipe, a plate, or a body * Body orifice, any opening in the body of a human or animal *Orifice plate, a restriction used to measure flow or to control pressure or flow, sometimes given specia ...
at each end. Fog from a fog machine is pumped in one side of the container, and allowed to flow out the other end. Although this technique does allow an individual to create low-lying fog "on the cheap" (when compared to the cost of renting cylinders of liquid CO2 or watertight containers with integral heaters), the volume of low-lying fog produced is typically less, and is more susceptible to atmospheric disturbances.


Nitrogen

Liquid nitrogen Liquid nitrogen—LN2—is nitrogen in a liquid state at low temperature. Liquid nitrogen has a boiling point of about . It is produced industrially by fractional distillation of liquid air. It is a colorless, low viscosity liquid that is wide ...
(N2) is used to create low-lying fog effects in a manner similar to dry ice. A machine heats water to at or near the boiling point, creating steam and increasing the humidity in a closed container. When liquid nitrogen is pumped into the container, the moisture rapidly condenses, creating a thick white fog. A fan placed at the output of the container directs the fog where it is needed, creating a rolling fog that lies low to the ground. 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. Dry Fogger is also a trademarked name for a particular brand of this style of fog machine. Liquid air can be used instead of nitrogen.


Historical usage

The
Globe Theatre The Globe Theatre was a theatre in London associated with William Shakespeare. It was built in 1599 by Shakespeare's playing company, the Lord Chamberlain's Men, on land owned by Thomas Brend and inherited by his son, Nicholas Brend, and gra ...
(1598–1613) reportedly used smoke effects during performances for atmosphere and special effects. On 23 March 1934,
Adelaide Hall Adelaide Louise Hall (20 October 1901 – 7 November 1993) was an American-born UK-based jazz singer and entertainer. Her long career spanned more than 70 years from 1921 until her death and she was a major figure in the Harlem Renaissance. Hal ...
opened at Harlem's
Cotton Club The Cotton Club was a New York City nightclub from 1923 to 1940. It was located on 142nd Street and Lenox Avenue (1923–1936), then briefly in the midtown Theater District (1936–1940).Elizabeth Winter"Cotton Club of Harlem (1923- )" Blac ...
in ''The Cotton Club Parade'' 24th Edition. In the show Hall introduced the song " Ill Wind", which
Harold Arlen Harold Arlen (born Hyman Arluck; February 15, 1905 – April 23, 1986) was an American composer of popular music, who composed over 500 songs, a number of which have become known worldwide. In addition to composing the songs for the 1939 film ...
and
Ted Koehler Ted L. Koehler (July 14, 1894 – January 17, 1973) was an American lyricist. He was inducted into the Songwriters Hall of Fame in 1972. Life and career Koehler was born in 1894 in Washington, D.C. He started out as a photo-engraver, but w ...
wrote especially for her. It was during Hall's rendition of "Ill Wind" that nitrogen smoke was used to cover the floor of the stage. It was the first time such an effect had ever been used on a stage and caused a sensation.


Smoke testing

When using smoke machines, a common test is to fill the venue to the full capacity with smoke to see if there are any
smoke detector A smoke detector is a device that senses smoke, typically as an indicator of fire. Smoke detectors are usually housed in plastic enclosures, typically shaped like a disk about in diameter and thick, but shape and size vary. Smoke can be detecte ...
s still live, or if there are any leaks of smoke from the venue sufficient to set off detectors in other parts of the venue being tested. This practice is known as a smoke test. Smoke machines are commonly used in the testing of larger
hvac Heating, ventilation, and air conditioning (HVAC) is the use of various technologies to control the temperature, humidity, and purity of the air in an enclosed space. Its goal is to provide thermal comfort and acceptable indoor air quality. HV ...
systems to identify leaks in ducting, as well as to visualize air flow.


Awards

The techniques and technology for creating smoke and fog effects are continually evolving. The individuals who create and develop theatrical fog for use in the entertainment industry have received numerous recognition for their efforts.


Academy of Motion Picture Arts and Sciences


Technical achievement awards

* On March 7, 1992, the Academy of Motion Picture Arts and Sciences presented a Technical Achievement Award to Jim Doyle for the design and development of the Dry Fogger, which uses liquid nitrogen to produce a safe, dense, low-hanging dry fog. * On February 28, 1998, the Academy of Motion Picture Arts and Sciences presented a Technical Achievement Award to James F. Foley (UCISCO); Charles Converse (UCISCO); F. Edward Gardner (UCISCO); Bob Stoker and
Matt Sweeney Matt Sweeney (born July 2, 1969) is an American musician and record producer best known as a guitarist of Skunk, Chavez, and supergroup Zwan. Early life and education Sweeney was born in New Jersey. His father was John D. Sweeney, a professo ...
for the development and realization of the Liquid Synthetic Air system. * On January 4, 2008, the Academy of Motion Picture Arts and Sciences presented a Technical Achievement Award to Jörg Pöhler and Rüdiger Kleinke of OTTEC Technology GmbH for the design and development of the battery-operated series of fog machines known as "Tiny Foggers."


Scientific and engineering award

* On March 25, 1985, the Academy of Motion Picture Arts and Sciences presented a Scientific and Engineering Award to Günther Schaidt of Rosco Laboratories for the development of an improved, non-toxic fluid for creating fog and smoke for motion picture production.


Adverse health effects


Carbon dioxide

Unsafe concentrations of carbon dioxide can cause
headache Headache is the symptom of pain in the face, head, or neck. It can occur as a migraine, tension-type headache, or cluster headache. There is an increased risk of depression in those with severe headaches. Headaches can occur as a result ...
s,
nausea Nausea is a diffuse sensation of unease and discomfort, sometimes perceived as an urge to vomit. While not painful, it can be a debilitating symptom if prolonged and has been described as placing discomfort on the chest, abdomen, or back of the ...
,
blurred vision Blurred vision is an ocular symptom where vision becomes less precise and there is added difficulty to resolve fine details. Temporary blurred vision may involve dry eyes, eye infections, alcohol poisoning, hypoglycemia, or low blood pressure. ...
,
dizziness Dizziness is an imprecise term that can refer to a sense of disorientation in space, vertigo, or lightheadedness. It can also refer to disequilibrium or a non-specific feeling, such as giddiness or foolishness. Dizziness is a common medical c ...
and
shortness of breath Shortness of breath (SOB), also medically known as dyspnea (in AmE) or dyspnoea (in BrE), is an uncomfortable feeling of not being able to breathe well enough. The American Thoracic Society defines it as "a subjective experience of breathing disc ...
. Higher concentrations will result in
loss of consciousness Loss may refer to: Arts, entertainment, and media Music * ''Loss'' (Bass Communion album) (2006) * ''Loss'' (Mull Historical Society album) (2001) *"Loss", a song by God Is an Astronaut from their self-titled album (2008) * Losses "(Lil Tjay son ...
and
death Death is the irreversible cessation of all biological functions that sustain an organism. For organisms with a brain, death can also be defined as the irreversible cessation of functioning of the whole brain, including brainstem, and brain ...
due to
suffocation Asphyxia or asphyxiation is a condition of deficient supply of oxygen to the body which arises from abnormal breathing. Asphyxia causes generalized hypoxia, which affects primarily the tissues and organs. There are many circumstances that can i ...
. When using compressed carbon dioxide or
dry ice Dry ice is the solid form of carbon dioxide. It is commonly used for temporary refrigeration as CO2 does not have a liquid state at normal atmospheric pressure and sublimates directly from the solid state to the gas state. It is used primarily a ...
, care should be taken to ensure there is sufficient
ventilation Ventilation may refer to: * Ventilation (physiology), the movement of air between the environment and the lungs via inhalation and exhalation ** Mechanical ventilation, in medicine, using artificial methods to assist breathing *** Ventilator, a m ...
available at all times, and that procedures are in place to rapidly evacuate CO2 from any enclosed space in an emergency. Liquid carbon dioxide (−56.6 °C) and dry ice (−78.5 °C) present a significant risk of
frostbite Frostbite is a skin injury that occurs when exposed to extreme low temperatures, causing the freezing of the skin or other tissues, commonly affecting the fingers, toes, nose, ears, cheeks and chin areas. Most often, frostbite occurs in the han ...
if mishandled. Proper protective clothing, such as long sleeves and
glove A glove is a garment covering the hand. Gloves usually have separate sheaths or openings for each finger and the thumb. If there is an opening but no (or a short) covering sheath for each finger they are called fingerless gloves. Fingerless glov ...
s, should always be worn when handling these products. Liquid carbon dioxide, stored in compressed cylinders, also presents all the hazards attendant to materials under pressure and should be handled accordingly.


Liquid nitrogen

Nitrogen itself is relatively non-toxic, but in high concentrations it can displace oxygen, creating a suffocation hazard. Liquid nitrogen (−195.8 °C) presents a significant risk of frostbite or cold burn if mishandled. Proper protective clothing, such as long sleeves and gloves, should always be worn when handling these products. Liquid nitrogen is stored in compressed cylinders, and therefore presents all the hazards attendant to materials under pressure and should be handled accordingly.


Theatrical fog and artificial mists

A number of studies have been published on the potential health effects presented by exposure to theatrical fogs and artificial mists. The first study that was done by Consultech Engineering, Co. under contract to Actor's Equity. 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 The National Institute for Occupational Safety and Health (NIOSH, ) is the United States federal agency responsible for conducting research and making recommendations for the prevention of work-related injury and illness. NIOSH is part of the C ...
, and another one in 2000 by the Department of Community and Preventative Medicine at the
Mount Sinai School of Medicine The Icahn School of Medicine at Mount Sinai (ISMMS or Mount Sinai), formerly the Mount Sinai School of Medicine, is a private medical school in New York City. It is the academic teaching arm of the Mount Sinai Health System, which manages eigh ...
and ENVIRON; both prepared for
Actors Equity The Actors' Equity Association (AEA), commonly referred to as Actors' Equity or simply Equity, is an American trade union, labor union representing those who work in live theater, live theatrical performance. Performers appearing in live stage ...
and the League of American Theatres and Producers, focused on the effects on actors and performers in
Broadway Broadway may refer to: Theatre * Broadway Theatre (disambiguation) * Broadway theatre, theatrical productions in professional theatres near Broadway, Manhattan, New York City, U.S. ** Broadway (Manhattan), the street **Broadway Theatre (53rd Stree ...
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 focused on the use of theatrical fog in the commercial aviation industry for emergency training of staff in simulated fire conditions. This study that found eye and respiratory tract irritation can occur. In May 2005, a study published in the ''American Journal of Industrial Medicine'', 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. This study also found long-term exposure to smoke and fog was associated with both short-term and long-term respiratory problems such as chest tightness and wheezing. Personnel working closest to the fog machines had reduced lung function results. Th
Entertainment Services and Technology Association
has compiled a standard for theatrical fogs or artificial mists compositions for use in entertainment venues that "are not likely to be harmful to otherwise healthy performers, technicians, or audience members of normal working age, which is 18 to 64 years of age, inclusive." This standard was based (though not exclusively), upon the findings of

commissioned by ESTA and applies only those fog fluid compositions that consist of a mixture of water and glycol and glycerin (so called "water based" fog fluid). Short term exposure to glycol fog can be associated with headaches, dizziness, drowsiness and tiredness. Long term exposure to smoke and fog can be related to upper airway and voice symptoms. Extended (multi-year) exposure to smoke and fog has been associated with both short-term and long-term respiratory health problems. Efforts should be made to reduce exposure to theatrical smoke to as low a level as possible. The use of digital effects in post production on film and television sets can be considered a safer practice than using theatrical smoke and fog during filming,Teschke K, Chow Y, van Netten C, Varughese S, Kennedy SM, Brauer M
Exposures to atmospheric effects in the entertainment industry
J Occup Environ Hyg. 2005 May 2(5):277–84.
although this is not always practical.


See also

* Fog machine *
Haze machine Haze machines, or haze generators (commonly referred to as hazers), are effects machines similar to fog machines, designed to produce an unobtrusive, homogeneous clouds suspended in the air intended primarily to make light beams visible or create ...


References


External links


Theatre Effects U.S. – Many Fog FAQs Found Within This Site

Rosco U.S.A. – How Fog Machines Work

Ontario Ministry of Labour – Fog and Smoke Safety Guideline for the Live Performance Industry

– Fog Film Special Effects
{{DEFAULTSORT:Theatrical Smoke And Fog Scenic design