National Center for Environmental Health: Office of Global Health - Air Pollution

Air Pollution

Smog in Beijing.
(Smog in Beijing - Dr. Edwin P. Ewing, Jr.)

An estimated quarter of the world’s population is exposed to unhealthy concentrations of air pollutants, such as particulate matter, sulfur dioxide, and other chemicals. Nearly 2 million children younger than 5 years of age die every year from acute respiratory infections, which are often aggravated by environmental hazards. Air pollution (indoor and outdoor) is estimated to be responsible for nearly 5% of the global burden of disease.

Air quality is best observed on two levels: immediate local concerns and long-term global changes. Both local and global air quality will be shaped by rapid population growth, urbanization, industrialization, and the growth of “megacities”. The cross-border transport of pollutants such as ozone, as well as the gases and aerosols created from biomass burning will increase in importance as total emissions rise. Such pollutant transport can raise “background” pollution levels over large regions of the globe.

Air quality must be classified as “indoor” or “outdoor” air; each pose unique challenges and opportunities. Indoor air pollution is a major factor of respiratory infections in both rural and urban areas of developing countries. Indoor air is most affected by smoke and pollutants caused by biomass burning, tobacco, poor urban planning, mold, rodents, and insects. Outdoor air problems largely involve particulate sources such as factories and industrial areas, deforestation and forest fires; and modes of transportation such as cars, tractors, boats, or aircraft. Studies have shown that both indoor and outdoor air quality cause acute respiratory infections, asthma, heart and lung diseases, allergies, and several types of cancers.

Several challenges exist to improve air quality. The main challenge is the lack of solid knowledge and quantifiable data on both indoor and outdoor pollution and the links to chronic health problems. Next is the lack of agreement on international standards for air quality and emissions, such as the ongoing debate over the 1992 Kyoto Protocols. Finally, air quality improvements often conflict with international economic trends (from industrialization to the increase in transcontinental transport, urbanization, and the growth of “megacities”). Even where air quality regulations exist in developing countries, they are rarely enforced.

NCEH/ATSDR EXPERTISE AND EXPERIENCE

In the United States and Mexico, NCEH/ATSDR is currently studying the effect of outdoor air pollution on children’s asthma along the El Paso/Ciudad Juarez international trucking corridor and along both sides of the Imperial Valley. In Southeast Asia, NCEH/ATSDR has been working with the Malaysian Ministry of Health for the past 5 years to track the effects of air pollution from forest fires in the late 1990s. Results of these studies are expected to be used to prevent deaths and hospitalization due to haze. In China, NCEH/ATSDR has initiated a collaborative asthma study. Staff members returned from their first data-gathering mission in early November 2003.

NCEH/ATSDR has several global studies and investigations related to lead. Investigations in 2000 and 2001 reviewed blood lead levels of children on several islands in Micronesia. Also, NCEH/ATSDR compiled baseline data on school-age children in Indonesia as that country began the process of removing lead from gasoline. In conjunction with Mexican authorities, NCEH/ATSDR also reviewed blood lead levels of children in Mexico living near smelters.