10 Major Types of Hazardous or Toxic Air Pollutants

Hazardous air pollutants, also called “toxic air pollutants”, are the type of pollutants that are known to cause asthma, birth defects, reproductive effects, respiratory diseases, cancer, cardiovascular diseases, damage to the health and immune system, irritation in vital parts of the body, and other dangerous health and environmental effects.

Most hazardous or toxic air pollutants originate from the following anthropogenic sources: stationary sources such as gas stations, chemical plants, power plants, hazardous waste incinerators, factories, steel mills, and refineries; mobile sources such as buses, cars, and trucks; cleaning and dissolving agents/solvents, and building materials; oil leaks and spills, etc.

Hazardous air pollutants or contaminants could accumulate in the body, and they mix up more frequently than remain as individual substances after they are discharged. When pollutants mix, it complicates the problems of diagnosis and prevention of short-term and long-term illnesses.

These are the major hazardous air pollutants:

1. Benzene

Benzene is a chemical that is widely used in industries for manufacturing detergents, shoes, medicines, dies, explosives, etc. It is mostly discharged from gasoline fugitive emissions and gasoline motor vehicle exhaust, and also from stationary industry sources, but to a much lesser extent.

Tobacco smoke, cooking and heating systems, and various products used in homes may contain or release benzene which could increase the risk of cancer and cause drowsiness, nausea, tremors, depression of the central nervous system, intoxication, and even unconsciousness.

2. Diesel fuel and emissions

Diesel fuel and emissions cause a reported 80% of the total estimated cancer risk due to all types of hazardous air pollutants. Diesel exhaust is a complex mixture of vapors, gases, nickel, benzene, carbon monoxide, nitrogen oxides, sulfur dioxide, hydrocarbons, and fine particles that contain arsenic, etc. People who consistently inhale diesel fumes often experience lung cancer; diesel fuel and emissions increase cardiovascular and respiratory diseases which can cause death.

3. 1,3-Butadiene

1,3-Butadiene is a hazardous air pollutant that is discharged when diesel fuels and gasoline undergo incomplete combustion. It is used in the production of synthetic materials, can be found in tobacco smoke, and may be emitted from petroleum refineries, combustion of wood and agricultural products, wearing of vehicle tires, and burning forest. It irritates the eyes and mucous membranes and can cause headaches, fatigue, blurred vision, and dizziness.

4. Acrolein

Acrolein is emitted in industrial plants whenever it is being manufactured as an intermediate for other chemicals. Like 1,3-Butadiene, acrolein is also found in gasoline and diesel exhaust, tobacco smoke, wood products, forest fire smoke, paper mills, and other non-metallic mineral products. It causes irritation of the throat, nose, eyes, respiratory tract, and pulmonary edema.

5. Carbon tetrachloride

Although the wide use of carbon tetrachloride has been discontinued, because it has an estimated lifetime (remaining present in the atmosphere) of 50 years, its presence can still be discovered or felt upon testing. It irritates the respiratory tract, can poison various cell components, and affects the central nervous system.

6. Coke oven emissions

Coke is used to extract iron/metals from ores, create calcium carbide during manufacture of electrodes and graphite, and helps to convert coal into coke. Coke oven emissions contain benzene, which may cause severe dermatitis, cancer, conjunctivitis, and lesions of the digestive and respiratory systems.

7. Formaldehyde

Although formaldehyde is used to produce useful products such as embalming fluid, textiles, plywood, dies, and particle board, it is hazardous to the skin and respiratory system of animals. As an extremely toxic substance, it can cause cancer.

8. Chromium

Chromium is very important because, when used to coat metal parts and tools, it protects them corrosion and wear. But, hexavalent chromium, which is discharged during anodizing and electroplating operations/processes, causes cancer and complexities during pregnancy and childbirth.

9. Polycyclic organic matter

Polycyclic organic matter is produced when vegetable materials and fossil fuels undergo combustion; its compounds can be found in petroleum refineries, coal tar, motor vehicles exhaust, cigarette smoke, asphalt roads, paper mills, hazardous waste sites, smoke from wood burned in homes, and fly ash from electric power plants that use coal. Polycyclic organic matter can cause health problems in the skin, gastrointestinal tract, eyes, etc.

10. Mercury

Mercury is discharged into the atmosphere, remains active for a long time period, and can easily travel over great distances. It bio-accumulates in the food chain and oxidizes to produce a reactive gaseous form which enables it to increase its rate of deposition in various ecosystems. The downside is that mercury can increase the risk of lung cancer and affect reproduction.


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