Benzene vapor concentrations during a simulated crude oil spill

Benzene vapor concentrations during a simulated crude oil spill were measured to quantify the potential to exceed the Permissible Exposure Limits (PELs). The main concern was benzene vapor concentrations in worst-case situations. Vapors were measured using a variety of methods, including sample badge monitors, which are readily available for use by first responders. Worst-case conditions include rapid evaporation of high vapor pressure components (such as benzene) during the first hours of a spill; hot weather; enclosed areas; spreading surface area; and high API gravity crude oil (i.e., rich in high vapor pressure components). Under these conditions the time-weighted average benzene concentration exceeded 1 ppm during the first half hour of the simulation. Results several hours later, in open areas, or using lower API gravity crude oils were much lower. Calculated as an 8-hour average, exposures did not exceed the PEL of 1 ppm, although the 5 ppm short term exposure limit (STEL) was exceeded under the simulated wharf