Air Quality and Its Management

Abstract

Air quality is difficult to measure accurately and is usually considered in terms of particulates and vapors. The United States Environmental Protection Agency (USEPA) developed six key “criteria pollutants” in the 1970s: particulates, sulfur oxides, nitrogen oxides, ozone, carbon monoxide, and lead. Some of these compounds react in the atmosphere to create smog. More recently, USEPA has established 189 hazardous air pollutants (HAPs). Air is polluted by stationary sources (point sources, i.e., stacks, and fugitive sources, e.g., blowing dust) and mobile sources (e.g., vehicles). Fugitive emissions have been the most difficult to characterize and control. Air quality within the USA is managed primarily through Clean Air Act regulations, which include a unique state–federal partnership for permitting, called State Implementation Plans (SIPs). Air emission controls are based primarily on filtration (e.g., baghouses), scrubbers, and management techniques, such as the use of cleaner fuels and fugitive source management techniques (e.g., wetting, covering, enclosing, and sweeping).