Pollutants & Health Effects

Particulate Matter (PM)

Particulate matter (PM) consists of soot and dust particles.

PM 10: coarse particles—all particles smaller than 10 microns in diameter

PM 2.5: fine particles—all particles less than or equal to 2.5 microns in diameter. These particles are smaller than 1/8th the diameter of a human hair.

Sources of PM include diesel exhaust, soil dust, tire wear and fires. These particles penetrate deeply into the lungs and are captured by lung tissue. A major contributor to the PM pollution problem is exhaust from diesel vehicles, which account for 79% of the particulate emissions from mobile sources. The most dangerous aspect of PM pollution from diesel vehicles is the hundreds of different chemicals that are adsorbed by the particle as it travels from its source to our lungs.

PM and your Health

Exposure to PM pollution has been associated with respiratory and cardiac problems, infections, asthma attacks, lung cancer and decreased life expectancy. The World Health Organization estimates that 500,000 premature deaths each year may be associated with PM pollution. PM 2.5 is thought to be more dangerous because of its ability to penetrate deeper into lung tissue. A recent study found that even a small increase in PM 2.5 can result in a significant increase in mortality. In fact, the American Lung Association believes that PM 2.5 represents the most serious threat to our health. Those that are more susceptible to PM pollution include children, athletes, senior citizens and people with pre-existing respiratory conditions.

Ozone (O3)

Ozone is a highly reactive oxidizing agent that breaks down organic materials and is the primary component of smog. A naturally occurring form of oxygen, it is formed in minute amounts in our upper atmosphere by electric discharge or exposure to ultraviolet radiation. In the lower atmosphere, ozone is formed when hydrocarbons and nitrogen oxides—produced primarily by motor vehicles and various industrial practices—combine and chemically react in sunlight. When natural changes in temperature form “inversion layers” in the atmosphere, ozone is trapped and prevented from dissipating into the atmosphere. The result is a serious smog problem which has plagued Southern California for many years and, as populations grow, is becoming a problem for large cities throughout the country.

Ozone and your Health

Symptoms of ozone exposure include: coughing, shortness of breath, wheezing, fatigue, dry throat, chest pain, headache and nausea. Ozone exposure has been shown to cause inflammation of lung tissue, reduced lung capacity, the development of asthma, increased lung cancer mortality rates, and accelerated lung aging. Ozone reduces the respiratory system's ability to fight infection and remove foreign particles such as particulate matter. Long-term exposure to ozone can cause permanent lung damage, while short-term exposure appears to be reversible.

Who’s at risk?

Segments of the population that are more susceptible to ozone pollution include children, athletes, senior citizens, and people with pre-existing respiratory problems.

Hydrocarbons

Hydrocarbons are a class of reactive organic gases which are formed solely of hydrogen and carbon. Hydrocarbons contribute to the formation of ozone and the resulting smog problem. Carcinogenic forms of hydrocarbons are considered hazardous air pollutants, or air toxics.

The primary sources are combustion engine exhaust, oil refineries and oil-fueled power plants. The incomplete burning of any organic matter such as oil, wood or rubber also produces hydrocarbons. Other sources include evaporation from petroleum fuels, solvents, dry cleaning solutions and paint.

Hydrocarbons and your health

Hydrocarbons are a precursor to ground-level ozone, a serious air pollutant and key component of smog. A number of hydrocarbons are also considered toxic, meaning they can cause cancer or other health problems. [source]

Nitrogen Oxides (NOx)

Nitrogen monoxide (NO) and nitrogen dioxide (NO2) are the two forms of nitrogen oxides found in the atmosphere. Nitrogen oxides contribute to the formation of ozone, production of particulate matter pollution and acid deposition. The presence of nitrogen oxides gives smog its brown appearance. Factories, motor vehicles and power plants that burn fossil fuels produce nitrogen oxides. Diesel engines produce a disproportionately large amount of nitrogen oxides when compared to gasoline engines because of their high temperature combustion process.

Nitrogen Oxides and your health

Nitrogen dioxide has been shown to irritate lung tissue, cause bronchitis and pneumonia, and reduce resistance to respiratory infections. The presence of  nitrogen dioxide in the atmosphere can have synergistic effects with other forms of air pollution. The health effects of ozone are magnified in the presence of nitrogen dioxide. Frequent or long-term exposure to high levels of nitrogen oxides can increase the incidence of acute respiratory illness in children.

Carbon Monoxide (CO)

Carbon monoxide is a colorless, odorless gas that is produced by burning organic matter such as oil, natural gas, fuel, wood or charcoal. Motor vehicles produce 67% of the man-made carbon monoxide that is released into the atmosphere.

Carbon Monoxide and your health

Carbon monoxide displaces oxygen in red blood cells, which reduces the amount of oxygen carried to the brain and other body tissue. Exposure to carbon monoxide can result in fatigue, angina, reduced visual perception, reduced dexterity and death. Carbon monoxide is extremely deadly in an enclosed space, such as a garage or bedroom. The elderly, children, and people with pre-existing respiratory conditions are particularly sensitive to carbon monoxide pollution.

Sulfur Dioxide (SO2)

Sulfur dioxide is a colorless gas produced in the combustion of fossil fuels, such as coal and oil, by motor vehicles, refineries and power plants. A high level of sulfur dioxide in exhaust gas can interfere with emission control mechanisms for other pollutants.

Sulfur Dioxide and your health

Sulfur dioxide reduces respiratory volume and increases breathing resistance in those exposed, especially asthmatics. Studies have also shown that sulfur dioxide increases nasal airway resistance. Other research has shown that daily mortality rates are consistently associated with sulfur dioxide and ozone levels.

Air Toxics

Air toxics, also known as hazardous air pollutants, are generally organic chemicals, including some hydrocarbons that are highly evaporative in nature. Sources for air toxics include motor vehicles, chemical plants, paint, and any other operation that uses organic compounds. Benzene, formaldehyde, acetaldehyde, 1,3-butadiene and acrolein are typical examples of air toxics.

Air Toxics and your health

Air toxics have been shown to cause cancer. Benzene can cause aplastic anemia and acute myelogenous leukemia in occupational studies of workers exposed to it. Known health concerns related to aldehydes include cancer, asthma, and respiratory tract irritation. It is also believed that these air toxics have impacts on the reproductive system by causing chromosomal mutations. The nature of air toxics still poses many uncertainties about their true health effects. These chemical compounds have many different forms and metabolites as they are broken down, and little is known about how they interact with the body.