Survey report: control technology evaluation for controlling worker exposure to asphalt fumes from roofing kettles: kettle operated using an afterburner system at Glenwood Elementary School, San Rafael, California, report no. CT-231-19a.
From July 16 through 25, 2002, a field survey was conducted at Glenwood Elementary School in San Rafael, California where a built up asphalt roof was being installed to replace the old roof. The school was under going a complete renovation. A separate crew had previously removed the old roof, and a different crew installed the new roof. The survey was conducted to evaluate the effectiveness of using an afterburner system with a safety loading door fitted to an asphalt kettle to reduce worker exposure to asphalt fumes. Personal breathing zone and area air samples were collected and analyzed for total particulate (TP), benzene soluble fraction (BSF) of the TP, and total polycyclic aromatic compounds (PAC). These three analyses were chosen to represent indices of exposure to asphalt fumes. Air samples were collected with the afterburner on and kettle lid closed and afterburner off and kettle lid closed. Air samples were collected on the kettle operator and two roof level workers; area air samples were collected around the four comers of the kettle. The kettle operator's exposures to TP, BSF, and total PAC were all reduced when the afterburner was on and the kettle lid was closed when compared to when the afterburner was off and the kettle lid was closed. Reductions in exposures for the kettle operator of 23%, 54%, and 43% for TP, BSF, and total PAC were measured. Reductions of 33%, 66%, and 72% in TP, BSF, and total PAC were measured for the area air samples collected around the kettle. For the roof level workers, exposures to TP, BSF, and total PAC were reduced 33%, 27%, and 23%, respectively. Only the reduction of 66% for BSF seen in the area air samples collected around the kettle was statistically significant. None of the reductions measured for the kettle operator or the roof level workers were statistically significant (p less than or equal to 0.05). The greatest reductions in asphalt fume exposure occurred when the afterburners were on and the kettle lid was closed. Using the afterburner system with the kettle lid closed provided the most protection from asphalt fume exposure, particularly for the kettle operator. The kettle operator loaded all the asphalt into the kettle by opening the kettle lid instead of using the safety loading door allowing asphalt fumes to be emitted during this work activity. The kettle operator also spent half of the work day working on the roof, getting a similar asphalt fume exposure as the other roof level workers. These work practices may have had a negative effect on the percent reductions measured.
National Institute for Occupational Safety and Health, Division of Applied Research and Technology, Mail stop R-5, 4676 Columbia Parkway, Cincinnati, OH 45226