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ASTHMA

Air Pollution

Asthma

By Theodore M. Freeman, MD

A ir pollution is due to a variety of contaminants in the established the Environmental Protection Agency (EPA) to set

air and can occur in both indoor and outdoor environ-
and monitor National Ambient Air Quality Standards (NAAQS).
ments. Outdoor contaminants include carbon monox-
air-pollutants/naaqs-table.
ide, lead, sulfur dioxide, oxides of nitrogen, ozone (O3) particulate These standards can be found at https://www.epa.gov/criteria-
matter and biologic agents.1 Indoor air pollution is often due to Asthma is reversible obstructive airway disease. Each of the con-
many of the same contaminants but for the purposes of brevity taminants above has been established to have a negative impact on
this discussion will be restricted to outdoor agents. The sources asthma except for lead and carbon monoxide. Particulate matter
2
of outdoor air pollution are divided into point sources and mobile (< 10 um in diameter) has been associated with asthma exacerba-
sources. Point sources are fixed in location and are usually facto- tions in studies performed not only in the U.S. and Europe but also
1
ries and power plants that routinely emit gaseous and particulate in Australia, Brazil, China, and New Zealand. One interesting study
matter when operating. Mobile sources include everything that looked at particulates and incidence of respiratory disease in a valley
uses internal combustion as a power source, most importantly in Utah before, during, and after a labor strike that temporarily shut
2
motor vehicles. The Clean Air Act of 1970 as amended in 1990 down a steel mill in the valley. Both particulates and respiratory dis-

30 San Antonio Medicine • November 2018