In-depth survey report: control technology for controlling worker exposure to asphalt fumes from roofing kettles: kettle operated using the FRS-6000 (TM) at Dana Corporation, Columbus, Ohio, report no. ECTB-231-11a.
The five-day average of TP, BSF, and PAC exposures were 1.58 mg/m3, 1.08 mg/m3, and 186 microg/m3 respectively to the kettle operators, 0.34 mg/m3, 0.12 mg/m3, and 22 microg/m3 respectively in the area and building samples, and 0.77 mg/m3, 0.37 mg/m3, and 75 microg/m3 respectively to the roof-level crew. Whether the FRS-6000 filtration unit is used or not, these data show the kettle operator is being exposed to levels of asphalt fume higher than any other roofing worker. This puts the kettle operator at the highest risk of adverse health effects. There was no significant correlation between the square foot of roof replaced (i.e., asphalt used) in a day and the IP, BSF, and PAC exposures to the kettle operator for that day. This is most likely due to the kettle operator loading fewer asphalt kegs (l or 2) each time the kettle lid is opened during days where usage is low. During high asphalt use days, the kettle operator tends to load more kegs (3 or 4) each time the kettle is opened but does not necessarily open the door more often than on low usage days. This observation is site specific and largely a function of the kettle size used and the kettle operator's work habits. Visible emissions were observed from the kettle during skimming and filling and loading operations whether the filtration unit was on or off, while area samples taken a short distance away from the kettle indicated very low TP, BSF, and PAC concentrations over the sampling periods. The FRS-6000 exhaust ventilation rate provided sufficient containment while the kettle lid was closed, but was insufficient to control asphalt fume during kettle loading or skimming. Based on some initial real-time data, most of the kettle operator exposure comes when the kettle lid is opened. Due to the small sample size, variability caused by the wind, and net affect of the control, the benefit of using the FRS-6000 filtration unit could not be statistically measured. For example, the PAC concentration for the kettle operator was 185 microg/m3 when the control was not used and ranged between 27-381 microg/m3 when the control was used. While a reduction in exposure levels was not evident based on this studies data, the asphalt fume odor was noticeably diminished when the FRS-6000 was used. This observation was made by a number of onsite researchers and the kettle operators.