To acquire fumes, these roofing asphalts were heated to temperatures more than twice those used in the paving industry. The fumes then were collected, concentrated and used in animal experiments. The tests were challenged at once by a committee with representation from NAPA, the petroleum industry, and the roofing industry, reported the late Hugh Gillespie in NAPA's 1992 history, A Century of Progress . Anticipating workers dressed in moon suits, and class action suits from labor unions and neighborhoods through which paving had taken place, the industry fought back with tremendous vigor and unanimity. NAPA itself retained two toxicologists and sought to differentiate the properties of coal tar pitch from liquid asphalt, with which asphalt was conveniently lumped.
Data regarding the potential carcinogenicity of paving asphalt fumes in humans are limited.
No. 97-105, January 1997. Development of these guidelines and this document was truly a joint effort. This cooperative effort resulted in exhaust control guidelines for highway-class HMA pavers. Each paver manufacturer should develop and install exhaust ventilation systems with a minimum controlled indoor capture efficiency of 80 percent on all new self-propelled HMA pavers weighing 16,000 pounds or more and manufactured after July 1, 1997. Manufacturers of highway-class HMA pavers should certify the system's performance to purchasers of new pavers.