A laboratory rig for studying aspects of worker exposure to bitumen fumes

This study was performed to establish which factors related to the hot appl ication of bitumen products are relevant to worker exposure to benzene-solu ble matter (as part of the total fume emission) and to the polycyclic aroma tic compound (PAH) content of bitumen fume. Because personal exposure measu rements in field surveys can be influenced by many uncontrollable variables , a simple laboratory rig was developed in which bitumen fumes can be gener ated reproducibly under well-controlled conditions. Laboratory results were related to personal exposure measurements during asphalt paving and roofin g. A quantitative relationship for predicting the laboratory fume emission was derived, with bitumen volatility and temperature the only variables. Th e variable part of the equation is termed the fuming index (FI). The FI cor relates well with measured personal exposures in asphalt paving and in roof ing and can be used to predict average personal exposures during these acti vities if bitumen volatility, application temperature, and for paving, the asphalt type, are known. The laboratory fumes, generated at a standard temp erature of 160 degrees C, are representative for fumes emitted in the tempe rature range relevant for asphalt paving, those generated at 250 degrees C for roofing. The PAH profiles of the fumes collected as personal samples du ring asphalt paving and roofing operations were similar to those of the fum es generated in the laboratory from the same bitumen and at the same temper ature. Because it produces conditions representative of actual bitumen oper ations, this laboratory set-up is an excellent tool for assessing bitumens in terms of fuming tendency and PAH emissions/exposures.