Аннотация:Road traffic is one of the most significant sources of the atmosphere pollution in urban areas, which leads to serious ecological, economical, and social problems. Among the most toxic components of the road traffic emission are carbon, sulfur, and nitrogen oxides, hydrocarbons, airborne particulate matter, polycyclic aromatic hydrocarbons, heavy metals, and dioxins. Some other toxic components are formed within the zone of a highway influence during the day time due to photochemical processes. This chapter gives an analysis of various physical, chemical, and biochemical processes that occur in the vicinity of highway and lead to transformation of pollutants and their interaction with the environment.