Evaluation of Worker Exposure to Asphalt Roofing Fumes: Influence of Work Practices and Materials

Abstract

A field study was conducted on 42 asphalt-roofing workers at 7 built-up roofing sites across the United States. Sixteen out of 42 samples show levels of exposure to asphalt fumes that exceed the current American Conference of Governmental Industrial Hygienists' (ACGIH®)-recommended threshold limit value of 0.5 mg/m³ as benzene extractable inhalable particulate. Statistically, the geometric mean of all 42 worker samples was 0.27 mg/m³ (geometric standard deviation = 3.40), the average was 0.70 mg/m³ (standard deviation = 1.69) and the median value was 0.24 mg/m³. The impact of work practices is discussed including the use of a novel product that uses a polymer skin to reduce fumes from built up roofing asphalt. Its use resulted in a reduction of benzene soluble matter (BSM) of > 70%. Other testing measures utilized included total particulate matter, total organic matter, simulated distillation, and fluorescence analysis. Additionally, a controlled pilot study using 16 kettle-area and 16 worker samples clearly showed that when the temperature of the kettle was reduced by 28°C, there was a 38–59% reduction in fume exposure and a 54% reduction in fluorescence with standard asphalts. Reduction of BSM exposures using fuming-suppressed asphalt was also confirmed during this pilot plant study (81–92%), with fluorescence lowered by 88%. Confounding agents such as roof tear-off materials were also analyzed and their contribution to worker exposure is discussed.

Keywords:

• asphalt
• built-up roofing asphalt (BURA)
• fluorescence
• fumes
• fuming-suppressed asphalt
• roofing
• personal breathing zone (PBZ)

ACKNOWLEDGMENTS

Studies of all conventional roofing asphalt sites were funded by the Asphalt Roofing Environmental Council (AREC), for which the authors are grateful. All portions relating to the fuming-suppressed asphalt were financed by Owens Corning.

Notes

^ATanker—no kettles used on this job.

^A If BDL, then half the detection limit was used for the value in averaging the data.

^B Breakthrough likely at this level; therefore exposures represent a minimum value.