Chemicals Found in Smog

The haze of smog fills the air over a city.the smog of cairo image by Elmo Palmer from Fotolia.com

Smog is a combination of pollutants in the air that limits visibility and harms people and the environment. Many major cities throughout the world have smog problems, often caused by heavy automobile use, large manufacturing sectors and the burning of certain types of fuel for heat and energy. These activities inject into the atmosphere chemical pollutants that interact with sunlight to cause such problems as poor visibility and high ozone concentrations.

Sulfur Dioxide

Sulfur dioxide is found in industrial smog, which is the smoky haze produced by factories and manufacturing plants. Aside from the negative visual effects of industrial smog, the presence of sulfur dioxide in industrial smog can cause acid rain. The chief source of industrial smog is coal-burning, according to the University of California at Berkeley.

Volatile organic compounds (VOCs) are found in photochemical smog, which is the prevalent form of smog in America today. VOCs are one of two primary pollutants (the other is nitrogen oxide) that interact with sunlight to produce the secondary pollutant chemicals peroxyacetyl nitrates (PAN) and ground-level (tropospheric) ozone, according to the University of California at Berkeley.

Nitrogen oxide, along with the VOCs, is a primary pollutant present in photochemical smog. Both nitrogen oxide and VOCs enter the atmosphere via the use of fossil fuels, the burning of trees and the disposal of agricultural waste products, according to the University of California at Berkeley.

Ozone, the product of the interaction of sunlight with the primary pollutants, is a major component of dangerous smog. It is an odorless and colorless gas composed of three oxygen atoms. The U.S. Environmental Protection Agency (EPA) monitors the amount of ozone in the air and provides communities with a warning system to indicate dangerous levels. Some of the negative effects the EPA warns of include respiratory irritation, reduced lung function and increased aggravation of some respiratory diseases, such as asthma, emphysema and bronchitis.