Dear Van co2 is soluble in water which it spontaneously interconverts between CO2 and H2CO3 so I really think it would be extremely difficult in practice to get close to dangerous levels especially in a
theatre which has legal ventilation rules
Simple test, Load up a pea souper, lie down in front of it completely immersed in the "harmless" water
fog, Tell us how you feel after 5 minutes.
While co2 is Soluble in water the reaction that occurs inside a
fog machine is far from a 100% reaction. Most of the CO2 which dissolves into the water remains in the water in the
fog machine itself. Take a sip, it's fizzy after running a
fog cue. We tend to err on the side of caution here. As I view the
safety and health of all personel working for and around me I will continue the policy of limiting peoples exposure to CO2
fog. For reference you might find the following useful;
Smoke and
Fog Hazards
By Michael McCann, Ph.D., C.I.H.
Introduction
In the last 10 years, the use of
fog and
smoke to create
atmosphere or special lighting effects has greatly expanded, due
in great part to the influence of music videos.
There are a wide variety of products and machines used to
create
smoke and
fog effects, with varying degrees of hazard.
This dadta sheete only discusses non-explosive materials that
depend upon a change in physical state to create the
effect, not
a chemical reaction.
Fog and
smoke effects are created by generating a fine
mist, a dispersion of very small particles, or an actual
smoke by
burning organic materials. All smokes and fogs are easily
inhaled. Some chemicals used to generate the
smoke or
fog are
toxic; however even chemicals that are not appreciably toxic can
be irritating to the lungs. In particular, high risk groups such
s people with asthma or other respiratory problems, children, or
elderly, and people having to do deep breathing (e.g a musician
playing a wind
instrument or a singer) might be more susceptible
to inhalation of any material.
It is often difficult to obtain information on many of
these products, even from Material
Safety Data Sheets (MSDSs),
because many manufacturers claim that the compositions are trade
secrets. Manufacturers of these products often make extravagant
claims as to
safety. For example, many products state that the
chemicals used have been approved by the Food and Drug
Administration (FDA) for ingestion. However, the fact that it
might be safe by ingestion does not mean it is necessarily safe
by inhalation.
Some manufacturers also claim that air sampling studies
indicate that the concentration of their product in air is below
the Occupational
Safety and Health Administration's (
OSHA)
Permissible Exposure Limit (PEL). This is very misleading, since
OSHA PELs and the
Threshold Limit Values they are based upon are
intended to apply to workers in industry and do not usually
protect the general population, especially high risk groups as
discussed above.
Many manufacturers have done acute toxicity studies on
their products. These animal studies only tell the effects of
single exposures and not of repeated exposures. In addition
these studies would not
pick up reversible, respiratory
irritation which can be crucial to actors or singers.
Another problem is determining the length of exposure. The
assumption is that these fogs are used only for short
periods of time. However in film production, for example, a
particular scene could be reshot many times, thus lengthening the
period of exposure. Also in theater, actors could be exposed
daily. In addition most theaters or motion picture productions
do not have an efficient method for clearing out the
fog between
takes or scenes, so that there can be an accumulation of the
fog
chemicals over a period of time. This can result in longer
exposures not only for the actors but also the crew.
In attempts to evaluate the
safety of some of these fogs
and smokes, unions and other groups have had these products
analyzed. In addition, the National Institute for Occupational
Safety and Health (
NIOSH) and others have conducted air sampling
studies to try and evaluate the
safety of the products.
Hazards of Particular Fogs and Smokes
Dry Ice
Dry ice is one of the earliest types of materials used to
create
fog effects. Dry ice is frozen carbon dioxide, and when
exposed to air it sublimes directly from a solid to a gas. The
cold gas causes moisture to condense into a thick, low-lying
fog.
Dry ice is the safest way to generate
fog except in enclosed spaces where the carbon dioxide can accumulate and reduce the oxygen concentration in the air. This could cause
asphyxiation if the oxygen concentration falls below 19.5%.
There would also be a hazard if someone was lying down in the dry
ice
fog.
Petroleum Distillates
Many of the earlier types of fogs were based on kerosene,
fuel oil or other petroleum distillates. These were vaporized by
heating to generate a fine mist. Unfortunately inhalation of
these chemicals caused eye and respiratory irritation, chemical
pneumonia, and narcosis (dizziness, headaches, nausea,
etc.). In
addition, the mist of these petroelum distillates is a fire
hazard. I definitely recommend against any
fog product
containing fuel oil or other petroleum distillates.
Zinc Chloride
Smoke Generating Devices
A number of companies sell
smoke generators based on zinc
chloride (e.g.
smoke cookies,
smoke pots,
smoke candles,
smoke
bombs). Some of these also contain chlorinated hydrocarbons such
as perchloroethylene, a suspect carcinogen. The
smoke is
generated by heating or burning the product, which is classified
as a Flammable Solid, D.O.S. by the Department of Transportation.
These are available in sizes that generate small to very large
amounts of
smoke. The Material
Safety Data Sheets on many of
these products are not adequate and do not reflect their hazards.
Use of these
smoke devices in fire fighter training exercises has
resulted over the years in complaints of breathing problems,
chest paints, hot and cold flashes, headache, fever, fatigue,
sore throat, nausea, cough and even some fatalities. Some of
these symptoms might be due to chlorinated hydrocarbons, but most
are due to the generation of high concentrations of hydrochloric
acid from the reaction of the zinc chloride with water. In some
studies hydrochloric acid concnetration have been many times
higher than
OSHA PELs and even approach levels considered
immmediately dangerous to life or health. Even lower levels of
smoke has caused symptoms. I recommend against the use of zinc
chloride
smoke devices, or devices based on titanium chloride and
similar materials indoors or in outdoor situations where either
film crew or actors could be exposed to any substantial amount of
the
smoke.
Ammonium Chloride
Ammonium chloride (sal ammoniac) is a common method of
generating
smoke on
stage and outdoors. The
smoke is created by
heating the ammonium chloride. Air sampling studies have found
large concentrations of ammonium chloride, in some instances near
the
OSHA PEL for nuisance dusts. Air sampling studies have also
shown that some decomposition of the ammonium chloride to
hydrogen chloride occurs during this heating. The hydrogen
chloride dissolves in water in the respiratory
system to produce
hydrochloric acid, a respiratory irritant. The levels of
hydrochloric acid are much smaller than caused by the zinc
chloride
smoke devices, but are still high enough to cause
concern. It is not recommended that ammonium chloride be used
indoors or in enclosed spaces.
Mineral Oil
This includes oil crackers and diffusion foggers. Oil
crackers involved bubbling air through a drum of mineral oil.
The air bubbles reaching the surface contained "cracked" oil of
particle size 1 to 50 microns. This oil is not "cracked" in the
sense of chemically breaking down the oil but is merely creating
smaller droplet size. This has also been used in combination
with dry ice. The diffusion fogger produces a mineral mist of
less than 1 micron size by using a
compressor to force mineral
oil through a series of fine filters. Air sampling studies by
CalOSHA in an enclosed sound
stage 90'x75'x30' found that ten
minutes of fogging produced mineral oil concentrations for almost
2 hours that were 50% to 90% of the
OSHA 8-hour PEL for mineral
oil. However this PEL for mineral oil is based on its use as a
cutting oil in industry; no toxicological studies have been made
on inhalation of mineral oil of particle size less than one
micron. However there is concern about long term problems such
as lipid pneumonia since the very fine mineral oil mist gets deep
into the lungs and stays there. This is not recommended for use
indoors or where personnel could inhale the mineral oil.
Glycol Fogs
During the last decade, a whole range of products have been
developed that use mixtures of water and polyfunctional alcohols,
including ethylene glycol, propylene glycol, diethylene glycol,
triethylene glycol, polyethylene glycol and glycerin. In general
these are safer than most of the other fogs and smokes with the
exception of dry ice. Ethylene glycol and diethylene glycol are
toxic by ingestion, causing kidney damage and possible death; the
other glycols mentioned are considered only slightly toxic.
Ethylene glycol has been removed from most fogs after studies
showed that it is a teratogen (can cause birth defects).
Unfortunately long-term studies have not been done on inhalation
of the mists of most of these glycols, although respiratory
irritation is sometimes listed on Material
Safety Data Sheets.
A more serious concern is how the
fog is generated. These
mixtures are heated in a
fog machine that heats the liquid to a
temperature near 600 F. One air sampling study found significant
levels of acrolein in the mist generated, about 20% of the
OSHA
PEL. Acrolein is a strong respiratory and eye irritant.
NIOSH
is conducting studies on various fogs to determine the extent of
this decomposition product. It is likely that some chemicals
could generate more decomposition products than others.
Reformulation and finding ways to reduce the temperature needed
to create the mist are possible solutions. Despite these
problems, at this time the glycol fogs are probably the least
hazardous fogs to use, although some will probably turn out to be
safer than others.
Burning Orgnic Materials
The burning of gums such as olibanum gum (frankincense),
paper, and other materials can also generate
smoke. These smokes
are irritating and considerable amounts of carbon monoxide may
also be generated. In addition to the
smoke hazards, there is
the concern about the open flames. These materials should not be
burned inside or where people would be exposed to substantial
amounts of
smoke.
Types of Respirators
The following table lists the types of respirators to use
with different mists and fogs:
Table 1. Respirator Selection for
Smoke and
Fog
dry ice - none needed; test oxygen concentration in
enclosed spaces.
zinc chloride - acid gas cartridge and dusts and mist
filter; high concentrations need air-
supplied respirators
ammonium chloride - acid gas cartridge and dusts and
mists filter
mineral oil - dusts and mists filter
glycol fogs - organic vapor cartrdige and dusts and mists
filter
burning materials - dusts and mists filter for
smoke.
Recommendations
1.
Smoke and
fog on
stage, television and motion picture sets is
regulated by most Fire Departments. In New York City, for
example, you need a fire permit to use
smoke and
fog just as you
do for pyrotechnics.
2. All personnel (
stage or camera crew, actors,
etc.) should be
informed in
advance of the intention to use
smoke or
fog and the
type to be used. Before use, there should be a discussion of the
hazards and precautions being taken.
3. Obtain Material
Safety Data Sheets on all
smoke and
fog
products. In particular note whether the Reactivity section
lists any hazardous decomposition products.
4. The choice of product depends on whether it will be used
indoors or outdoors, in enclosed spaces, and whether people will
be exposed for any significant period.
5. Children, elderly and people with respiratory problems should
be informed of their possible higher risks. A medical opinion
should be obtained as to whether they should be exposed.
6. Use only
fog and
smoke machines with the chemicals recommended
by the manufacturer. Other materials may clog, or otherwise
interfere with proper operation of the machine. Keep the
fog
machine in good repair and use as instructed.
7. Use the minimum concentration of
smoke for the minimum period
of time necessary. Avoid heavy concentrations when people are
exposed.
8. Only allow essential personnel on the set or
stage when using
smoke and
fog effects. Also evacuate any nearby areas where the
smoke could reach.
9. On stages, interior sets or in enclosed areas, the crew should
wear respirators. Respirators should also be available for
anyone wanting one in any situation. All respirators should be
NIOSH-approved.
10. On stages, interior sets or in enclosed areas, rapidly
exhaust the
smoke once not needed and between takes.
Portable
ventilators of the type used in manholes can be used (e.g.
Coppus Engineering Corporation in Milbury, MA). In theaters it
is particularly important to exhaust the
fog away from the
audience or
orchestra pit. There have been situations where
children in the audience have gotten ill because of exposure to
fogs drifting from the
stage. Outdoors, large fans can be used
to blow away the
smoke.
11. For motion picture production, minimize the number of takes
to further reduce exposure of personnel.
12. When burning organic materials, have a
fire watch on
hand.
Sources of Additional Help
Written and telephone inquiries about hazards in the performing
arts and entertainment industries will be answered by the Art
Hazards Information Center of the Center for
Safety in the Arts.
The Information Center has a variety of written materials
available on this subject. Permission to reprint this data sheet
may be requested in writing from the Center. Enclose a self-
addressed, stamped
envelope for our publications list. Write:
Center for
Safety in the Arts, 5 Beekman Street, New York, N.Y.
10038. Telephone: 212/227-6220
This data sheet has been made possible through funding from
the New York State Department of Labor, Occupational
Safety and
Health Training and Education Program.
CSA is also supported
with public funds from the National Endowment for the Arts, New
York State Council on the Arts and the New York City Department
of Cultural Affairs.
(c) Copyright Center for
Safety in the Arts 1991