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How Smog Affects Health

The U.S. Environmental Protection Agency has found that tailpipe emissions from cars and trucks account for at least one-third of the air pollution in the United States. Exposure to the pollutants found in vehicle emissions have been shown to cause serious health problems. Although today's cars emit much less pollution than in the past, there are more cars on the road traveling more miles than ever before. Ohio E-Check is an important initiative aimed at improving the air we breathe. Modeling by Ohio EPA shows that emissions testing removes a minimum of 74 tons per day of volatile organic compounds (VOCs), carbon monoxide (CO) and nitrogen oxides (NOx).


Carbon Monoxide

Carbon monoxide is a colorless, odorless, poisonous gas emitted from the vehicle's exhaust as a result of an incorrect air and fuel mixture resulting in incomplete combustion. Carbon monoxide interferes with the blood's ability to carry oxygen to the brain, heart and other tissues. Unborn or newborn children and people with heart disease are in the greatest danger from this pollutant, but even healthy people can experience headaches, fatigue and reduced reflexes due to CO exposure.

Six Common Air Pollutants - Carbon Monoxide


Ozone is the major component in what we know as smog at ground level. Ozone is not emitted directly into the air but is produced in the lower atmosphere as a result of chemical reactions between oxygen and oxides of nitrogen in the presence of sunlight, especially in warm weather. This reaction normally results in a constant cycle where ozone is created and immediately broken down back into oxygen and NOx. However, hydrocarbons and other VOCs exist in the air which prevent ozone from breaking down, therefore increasing ozone concentrations. In the body, ozone reacts with lung tissue, causing inflammation of the lungs. Ozone can cause harmful changes in breathing passages, decrease the lungs' working ability and cause coughing and chest pains. Even healthy people are found to be sensitive to ozone exposure.

ozone pictureClick here to see how ozone is formed

Six Common Air Pollutants - Ozone

Nitrogen Oxide

Nitrogen oxides (NOx) are produced when fuel is burned at excessive temperatures. These compounds are essential to ozone formation and are a health problem themselves. The effect of NOx exposure on the respiratory system is similar to that of ozone and sulfur dioxide.

Six Common Air Pollutants - Nitrogen Dioxide

Hydrocarbons (Volatile Organic Compounds)

Hydrocarbon emissions result from fuel that does not burn completely in the engine. Hydrocarbons are a type of volatile organic compound (VOC). VOCs are chemicals containing hydrogen, carbon and possibly other elements that evaporate easily. Hydrocarbons and other VOCs contribute to the formation of ozone by increasing the amount of nitric dioxide in the air, which then combines with oxygen molecules to produce nitrogen and ozone. A number of exhaust hydrocarbons are also toxic, with the potential to cause cancer.  

General Hydrocarbon Information from U.S. EPA's website

Particulate Matter

Particulate matter includes microscopic particles and tiny droplets of liquid. Because of their small size, these particles are not stopped in the nose and upper lungs by the body's natural defenses but go deep into the lungs, where they may become trapped and cause irritation. Exposure to particulate matter can cause wheezing and similar symptoms in people with asthma or sensitive airways. Particulate matter can serve as a vector for toxic air pollutants.

Six Common Air Pollutants - Particulate Matter

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