Kay Teschke, Yat Chow, Michael Brauer, Chris van Netten, Sunil Varughese, Susan Kennedy. March 2003.

UBC’s School of Occupational and Environmental Hygiene have published this full report on the safety of atmospheric theatrical smokes and fogs in 2003.

WCB’s 8-hour Exposure Limit (EL) for mists of mildly refined oils is 0.2mg/m3, and of severely refined oils is 1mg/m3.

The American Conference of Governmental Industrial Hygienists (ACGIH) 8-hour time weighted average Threshold Limit Value (TLV) for mineral oil mist is 5mg/m3. Since 2001, the Notice of Intended Changes has not distinguished the type of mineral oil and has proposed a standard of 0.2mg/m3, as inhalable aerosol.

OBJECTIVES:

    • To study of exposures and health effects among entertainment industry productions, as well as special effects technicians;
    • To identify constituents of the fluids used to generate fogs and smokes ;
    • To identify constituents of the products that result from the thermal degradation;
    • To monitor aerosol concentrations on set (size and distribution);
    • To sample productions that use atmospheric effects, and measured the area exposures to aerosols, specific glycols, aldehydes, and polycyclic aromatic hydrocarbons;
    • To measure exposures to aerosols and polycyclic aromatic hydrocarbons among cast, crew, musicians, and special effects technicians;
    • To identify factors associated with increased and decreased personal exposure levels;
    • To make recommendations about control measures based on the results of the study;

Fluid Types:

    • Glycol
    • Mineral Oil
    • Glycol and Mineral Oil
    • Dry Ice

Aldehydes Measured:

    • Acetaldehyde
    • Acrolein (2-propenaldehyde)
    • Benzaldehyde
    • Butylaldehyde
    • Formaldehyde
    • Hexaldehyde
    • Propionaldehyde
    • Valeraldehyde

“On average, the largest proportion of the aerosol (61%) was small enough to reach the alveolar region of the lungs. These fine aerosols (<3.5 microns) are not visible and can stay suspended in the air for long periods (hours to days), whereas larger aerosols (>10 microns) stay suspended for only second to minutes. Glycol fogs tended to have higher proportions of aerosol in the larger nasopharyngeal size ranges, whereas mineral oil and combined fog types had more in the alveolar size range.”

RESULTS:

    • Exposures to mineral oils tended to be higher than exposures to glycols
    • Mineral oil aerosols were on average smaller than the glycols
    • The arithmetic mean of the personal mineral oil mist exposures exceeded the current standard for mildly refined mineral oils set by the WCB (0.2mg/m3) and the proposed ACGIH TLV for all mineral oils. It was very close to the EL for severely refined oils (1mg/m3).
    • None of the glycol samples exceeded the current glycerin mist standard of 10mg/m3.
    • It is important to remember that the standards must be reduced for personnel whose shifts are longer than 8 hours
    • There was no evidence of high levels of aldehydes or PAHs, suggesting little or no thermal degradation of the fog materials
    • All personal samples has PAH levels more than 1000 times lower than the current WCB Exposure Limit and ACGIH TLV for naphthalene: both are 8-hour limits of 10ppm (52mg/m3)
    • Average measurements for aldehydes in the area of the fog machines were low
    • The most important factors determining exposures to the fluids were distance from the fog machine (the close, the higher the exposure), the number of fog machines used, and the percent time spent in the visible fog
    • Grips had higher than expected exposures based on these factors, and sound technicians lower exposures.

HEALTH RESULTS:

    • Entertainment industry employees had increased rates for most of the ongoing or chronic symptoms evaluated
      • nasal symptoms
      • cough
      • phlegm
      • wheezing
      • chest tightness
      • shortness of breath on exertion
      • current asthma symptoms
    • The entertainment industry employees had reduced average levels of lung function suggesting that entertainment industry employees may be at risk for chronic upper and lower airway irritation and airflow obstruction
    • Increased acute symptoms of dry cough or dry throat, and increased acute headache, dizziness and tiredness were significantly associated with the use of glycol

In conclusion, these findings indicate that both acute and chronic upper airway irritation is seen in association with increased exposure to theatrical fog aerosol regardless of the type of fog raw materials used. Chronic lower airway or chest symptoms (asthma-like symptoms in the past 12 months, wheezing, chest tightness) and airflow obstruction appear to be linked to chronic (but not acute) exposure to fog aerosols.”

To read the full document, and to print, click here (465 kB).

 

STUDY SUMMARY AND RECOMMENDATIONS

  1. The industry should start working on exposure control plans for mineral oil in order to comply with regulations and to prevent the health effects observed in this study
  2. Although glycol levels were below regulatory limits, the findings suggest that exposure minimization would be a reasonable approach for glycol fluids as well.
  3. Exposure reduction might be achieved by:
    • increased emphasis on other methods to create generalized atmospheric haze (e.g. filters, post-production computerized methods);
    • more conscious decision making in every production about the necessity (or not) of chemically generated special effects;
    • consideration of other products where feasible, eg., fresh de-ionized water mists or steam for short-lived effects, use of liquid nitrogen;
    • maximizing the distance between employees and fog machines, minimizing the number of machines used, reducing the time fog machines are on, minimizing the time that employees spend in visible fog;
    • scheduling filming that uses fogs near the end of a production day so that the residual airborne mist is given time to settle when no one is on the set;
    • ventilating the sets with fresh air during and after fog use; and
    • training about potential exposures and health effects resulting from the use of smokes and fogs
  4. Where theatrical smokes and fogs continue to be used, exposures should be monitored to ensure that control methods are working

To read the full study summary, and to print, click here (203 kB).

For further industry information, you can find our air quality resources here.