Polycyclic Aromatic Hydrocarbons in the Environment: Environmental Fate and Transformation

Polycyclic aromatic hydrocarbons are toxic and carcinogenic compounds that occur in the environment and derive from two classes processes: petrogenic and pyrogenic processes. The petrogenic part derives from oil- and drilling activities, including oil disasters, spills, and pollution from industrial sites, refineries, and most importantly traffic exhaust emissions, while the pyrogenic part derives from fires, forest fires, volcanic eruptions, and incineration. PAHs have long degradation periods, and recent studies show high accumulated concentrations in soil, aquatic, and atmospheric environments. Particularly with the advent of the winter season, pollution and pollution migration increases by the atmospheric influences on smog clouds, from air to soil, air to water reserves, and from air to humans. This review maps the recent measurements and concentrations of PAHs worldwide, with particular focus on highly exposed regions such as China, India and former Eastern European countries. Monitoring and mapping the fate of PAH is of particular value to environmental scientists, given the carcinogenic and toxic properties of several PAHs. As also reported in this review, the carcinogenicity and toxicity varies with the chemical and molecular character of PAHs varies with size and shape, and the carcinogenic and toxic effect can be higher according to season, type of fuel and source of pollution, and also by the size of the exposed region/site. PAHs are an ubiquitous pollutant class that has to be included in climate regulations at the same level with CO2 and NOx, given their longer half-life and chemical properties which gives a wide range of toxic derivatives during degradation.