Hazardous (Organic) Air Pollutants

Abstract

Organic compounds consist of a potentially large group of air pollutants and many of these compounds are toxic. Apart from their impacts on human health, organic compounds associated with fine particles can also influence visibility degradation and radiative transfer through the atmosphere by scattering and absorption. Some organic pollutants also play an important role in the formation of photochemical smog. There are three most important groups of toxic organic air pollutants: volatile organic compounds (VOCs), polycyclic aromatic hydrocarbons (PAHs), and dibenzo- p -dioxins and dibenzofurans (PCDD/Fs). This article elucidates the characteristics, sources and distribution, and the health impacts of atmospheric VOCs, PAHs, and PCDD/Fs. The first two groups of compounds are produced by natural and anthropogenic sources, in which the anthropogenic inputs usually outweigh the natural inputs. Dibenzo- p -dioxins and dibenzofurans have never been produced intentionally. On entering the atmosphere they are removed either by photodegradation, or wet or dry deposition. Some of these groups of compounds exhibit toxic, mutagenic, and carcinogenic effects. Polycyclic aromatic hydrocarbons and PCDD/Fs belong to the group of persistent organic pollutants (POPs), exhibiting high lipophilicity and resist transformation. Therefore, they bioaccumulate in animal and human adipose tissues. As a result, these groups of compounds pose a threat to human health and to the environment.