Air Pollution–Related Illness

• Some air pollutants cause the airways to narrow, leading to cough, wheezing, and shortness of breath.

• Diagnosis is based on a history of exposure to air pollutants.

• Doctors do pulmonary function testing to determine whether the lungs are affected.

• Symptoms are treated.

(See also Overview of Environmental and Occupational Lung Disease.)

Air pollution contributes significantly to a number of health problems. Air pollution can affect lung function, trigger asthma and COPD (chronic obstructive pulmonary disease) exacerbations, and increase the risk of respiratory infections and lung cancer. Air pollution also increases the risk of heart attacks, the development of coronary artery disease, and stroke. People living in areas with a large volume of traffic have an elevated risk of air pollution–related health problems.

The major components of air pollution are

• Nitrogen dioxide (from combustion of fossil fuels)

• Ozone (from the effect of sunlight on nitrogen dioxide and hydrocarbons)

• Carbon monoxide

• Particulate air pollution (suspended solid or liquid particles)

• Sulfur oxides

Outdoor air pollution is an important contributor to indoor air pollution. In addition, sources of indoor air pollution include tobacco smoke, indoor cooking (including gas stoves), construction, and renovation. Burning of biomass fuel (for example, wood, animal waste, crops) for cooking and heating is an important pollution source in countries that rely on biomass fuel.

The U.S. Environmental Protection Agency (EPA) sets air quality standards for oxides of nitrogen, ozone, oxides of sulfur, carbon monoxide, lead, and particulates established as the criteria air pollutants in the Clean Air Act.

Ozone, which is the major component of smog, is a strong respiratory irritant and oxidant. Ozone levels are highest in the summer and in the late morning and early afternoon. Short-term exposures can cause shortness of breath, chest pain, and airway hyperreactivity. Children who regularly participate in outdoor activities during days on which ozone pollution is high are more likely to develop asthma.

Oxides of sulfur result from combustion of fossil fuels. Sulfur oxides can inflame the airways, possibly increasing the risk of chronic bronchitis as well as causing the airways to narrow.

Oxides of nitrogen form primarily from vehicle emissions and can irritate the airways and cause asthma.

Carbon monoxide is a product of incomplete combustion of fossil fuels and interferes with oxygen delivery to tissues by binding to hemoglobin, the protein in red blood cells that transports oxygen. Very high levels of carbon monoxide are not likely to occur outdoors.

With removal of lead from motor vehicle gasoline, lead levels in the air have decreased significantly in the United States.

Particulate air pollution is a complex mixture of solid particles and liquid droplets found in the air. The particles can originate from a variety of sources (including diesel exhaust, smoke stacks, and construction) and have both local and body-wide (systemic) inflammatory effects. Wildfire smoke, another important source of particulate air pollution, can impact people hundreds of miles from the source of the fire. Particulate air pollution increases death rates from all causes, especially heart and lung disorders.

In addition to being an important source of particulate matter, wildfire smoke also contains carbon dioxide, water vapor, carbon monoxide, hydrocarbons, nitrogen oxides, and trace minerals.

The nanotechnology industry creates extremely small particles of different substances, such as carbon, for various uses. Nanoparticles and ultrafine particles are less than 100 nanometers in size. For comparison, a human hair is about 100,000 nanometers in diameter, so it would take 1000 nanoparticles to equal the thickness of one hair. Certain nanoparticles and ultrafine particles have been associated with increased respiratory symptoms in people with asthma.