The Effects of Industrial Smog

Industrial smog is a mixture of pollutants released by fossil fuel combustion. Many components of industrial smog can have serious implications for human health and the environment if present in excess concentrations; these include sulfur dioxide, particular matter (dust and soot), carbon monoxide and sometimes mercury or lead. Government agencies, such as the Environmental Protection Agency, regulate industry to prevent emission of significant quantities of these harmful compounds.

Thermal Inversion

• A thermal inversion is the most serious and potentially life-threatening problem associated with industrial smog. In basin-shaped areas or valleys, a warm layer of air can sometimes trap a cooler layer near the ground; since the air does not mix, the pollutants do not disperse and can reach high concentrations. The elderly are especially vulnerable under these conditions. According to "Essential Environment," a thermal inversion in Donora, Pennsylvania, in 1948 trapped smog from a steel and wire factory; nearly half the town's residents fell ill and 21 died. A similar event in London in 1952 resulted in the deaths of roughly 4,000 people.

Acid Rain

• Sulfur dioxide and nitrogen oxides can react with water vapor to form sulfuric acid. This strong acid dramatically decreases the pH of water. Sulfuric acid formed by the reaction between sulfur dioxide from industrial smog and water vapor can acidify rainwater, leading to the phenomenon called acid rain -- rainwater with an unusually low pH. Acid rain can damage plant life, acidify lakes and streams and accelerate erosion of human structures like statues or buildings made of stone.

Health Effects

• Carbon monoxide can bind to hemoglobin, the protein in human red blood cells that carries oxygen from the lungs to the tissues, and prevent it from transporting oxygen. High concentrations of carbon monoxide--like those found in industrial smog--can be hazardous to human health. Heavy metals like mercury and lead can enter the food chain, accumulate in the tissues of living organisms and cause central nervous system damage if present in high concentrations, especially in small children. Sulfur dioxide is also toxic at high concentrations. All these pollutants are carefully regulated in developed nations owing to their potential health effects.