For example, volcanoes emit sulfur oxides and ash, and lightning produces ozone. There are two classifications of air pollutants - primary and secondary. Primary pollutants are produced directly by industrial sources. Secondary pollutants are created by the primary pollutant's interaction with the environment. Smog is a combination of primary and secondary pollutants.
Some pollutants have negative effects on the body.
For example, carbon monoxide binds to hemoglobin in the red blood cells and reduces the amount of oxygen carried in the blood. Ozone and the oxides irritate the air passageways in the lungs, while other pollutants irritate the eyes. When exercisers in high-pollution areas breathe through the mouth, the nasal mucosa's ability to remove impurities is bypassed, and many pollutants can be inhaled. This irritates the respiratory tract and makes the person less able to perform aerobically. Pollutants can irritate the respiratory tract and make the person less able to perform aerobically.