Definition

• A primary pollutant emits from the source into the atmosphere directly, retaining the same chemical form. This differs from secondary pollutants, which are formed by atmospheric reactions to primary emissions causing a chemical change. Both categories of pollutants damage the environment and can cause or worsen health problems.
  
  

Common Primary Pollutants

• The most common primary pollutants are those emitted in everyday activities. The five most common affect day to day activities and health, as well as damaging the environment.
  
  Carbon monoxide (CO) emits from incomplete combustion of automotive vehicles. This odorless, colorless gas causes headaches, drowsiness, and fatigue. Prolonged exposure to it in an enclosed space can cause death.
  
  Nitrogen oxides (NOx, NO) emit from the exhaust of automotive vehicles and industrial activities. On a smaller scale they're also produced when burning wood or kerosene, when using gas stoves, and by smoking. Prolonged exposure causes respiratory problems. Nitrogen oxides reacts with sunlight leading to the formation of smog and ozone.
  
  Sulfur oxides (SOx) such as sulfur dioxide emit during coal burning. These pollutants contribute to the development of acid rain. Asthmatics exposed to low levels of sulfur dioxide experience respiratory problems, especially during exercise. Short term exposure to high levels of sulfur dioxide cause breathing difficulties, burn the nose and eyes, and cause airway obstructions. Long-term exposure to the pollutant causes changes in lung function.
  
  Volatile organic compounds (VOCs) emit from incomplete combustion of automotive vehicles and industrial sources, and on a smaller scale, from every day items, like paints, paint strippers, cleaning supplies, pesticides, copiers and printers, and thousands of other sources. Levels of VOCs are usually higher indoors than outdoors. Prolonged or persistent exposure can cause eye, nose, and throat irritation, headaches, loss of coordination, nausea, and may damage the liver, kidneys, and/or central nervous system. Moreover, some VOCs cause cancer.
  
  Particulate matter, including dust, ash, and salt particles, can form naturally or from man-made sources. These pollutants adversely affect lung health.
  
  

Examples

• The ash produced by a volcanic eruption is a naturally-occurring example of the formation of a primary pollutant. The carbon monoxide and nitric oxide produced by automobiles is a man-made example of the formation of a primary pollutant. The VOCs produced by making copies on the office copier is another example of the formation of a primary pollutant.