The Fog & Smoke Working
Group, part of PLASA's Technical Standards Program, developes
standards for theatrical fogs and recommended practices for using
fog-making equipment safely and effectively. One of the first steps
in the standards-drafting process is to identify existing exposure
standards for the fog components. Well-recognized exposure standards
exist for the materials used in oil-based fogs and hazes, dry ice
fogs, and liquid nitrogen fogs, but fewer standards exist for the
compounds used to make what are commonly called "glycol-based fogs,"
and the standards that do exist are not well known.
To find out more about what the scientific and industrial hygiene
community knows about the chemicals used to make glycol fogs, PLASA
issued a request for quotations for a survey of the relevant literature. The RFQ was sent to
51 companies that have a Certified Industrial Hygienist on staff,
and a dozen bids were received. Two bids were accepted, and two
companies conducted independent literature surveys: The Cohen Group
of San Mateo, CA and HSE Consulting and Sampling of Omaha, NE. The
studies were paid for by ESTA, the Professional Lighting And Sound
Association (PLASA) of Britain, and the Professional Lighting and
Sound Association of Germany (VPLT).
The Cohen Group report and
the HSE Consulting report are
not identical documents, but are substantially congruent in their
findings. Both reports state that all of the chemicals they studied
(glycerin and five dihydric alcohols) are of low toxicity. Some
of the chemicals are of such low toxicity that no maximum allowable
concentrations have ever been established, even though they are
used in a wide variety of industrial applications. A few of the
chemicals have permissible exposure limits defined by a variety
of governmental bodies in the US, UK and Germany, but these exposure
limits are believed to be higher than the levels needed to produce
a heavily fogged theatrical environment. Neither report gives any
indication that performance environments should be evaluated in
a manner different than that used for other industrial work sites.
The Cohen Group report, however, does note that the existing concentration
data may not be valid for infants, the elderly, or those with impaired
The Fog & Smoke Working Group has used the data in the
Cohen Group and HSE Consulting reports to help draft a standard
for theatrical fog created with solutions of water and one or more
di- or tri-hydric alcohols. That standard, ANSI E1.5, can be found on the TSP's Published Documents page.