Abstract |
The report summarizes the air pollution problem of the asphalt industry-hot-mix asphalt plants and roofing manufacture--emphasizing particulate emissions. It outlines industrial processes, types and sources of pollutant emissions, and current and required controls. Particulates are the principal emission from the industry; sulfur oxides, nitrogen oxides, odors, and hydrocarbons are emissions of minor importance. Approximately 200,000 metric tons of these pollutants (except for odor, per se) were emitted in the U.S. in 1968, with substantial control only for particulates. In spite of developed controls, the industry still has air pollution problems. Emitted pollutants contribute to a dense and foggy fume and cause most of the public's complaints. Particulates can be controlled by wet or dry methods (or a combination of the two), by fabric filters, or by baghouses. Emissions of sulfur oxides, nitrogen oxides, and hydrocarbons are not significant qualitatively, but each contributes to the odor and smog problems and should be controlled. Control devices can be used on asphalt plants. Electrostatic precipitators are not usually considered because of their initial cost and rather high volume. Control methods are available for the principal pollutant, particulates; however, as in many other industries, available controls are often not being installed. (Modified author abstract) |