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Air Pollution Harms Children's Lungs for Life

Children exposed to higher levels of particulate matter, nitrogen dioxide, acid vapor, and elemental carbon have significantly lower lung function by the age of 18. At this age the lungs are nearly mature and lung function deficits are unlikely to be reversed. Children that were exposed to air pollution have significantly reduced growth and development of their lung. The lungs of children living in communities with higher concentrations of nitrogen dioxide, particulate matter, and acid vapor develop and grow slower and are less able to circulate air. This decrease in lung development has permanent adverse effects in adulthood.

Children who move from highly polluted communities experience an increase in lung development if the new communities have lower particulate matter levels. These children continue to have decreased lung development if the new communities have an equivalent or higher pollution levels. Days with higher ozone levels resulted in significantly higher school absences due to respiratory illness. Children who were exposed to higher concentrations of particulate matter were much more likely to develop bronchitis.

Asthma has captured a great deal of attention for several years. The prevalence of asthma in the U.S. has increased by more than 75% since 1980. The national average of people diagnosed with asthma 10.1%. Nearly 667,000 school-aged children in California have experienced asthma symptoms during the past 12 months. Air pollution plays a well-documented role in asthma attacks.

One of the perplexing aspects to asthma is that the prevalence is increasing in all industrialized countries. With industrialization comes the persistence of air pollution in urban areas. Much air pollution is due to vehicles. Air pollution is convincingly associated with many signs of asthma aggravation, including pulmonary function decrements, increased bronchial hyperresponsiveness, visits to emergency departments, hospital admissions, increased medication use and symptom reporting, inflammatory changes, interactions between air pollution and allergen challenges, and immune system changes.

The ARB-funded Children's Health Study at the University of Southern California found that children who lived in communities with high ozone levels were more likely to develop asthma than children living in areas with less ozone pollution. In another ARB-funded study, researchers at the University of California, Irvine found a positive association between some volatile organic compounds and symptoms in asthmatic children from Huntington Park. There is abundant clinical evidence of asthmatic responses to indoor aeroallergens and other common indoor air pollutants from gas stoves, fireplaces, and environmental tobacco smoke have been less well characterized. These combustion sources produce a complex mixture of pollutants, many of which are respiratory irritants.

A panel of 164 asthmatics residing in the Denver, Colorado’s metropolitan area recorded in a daily diary the occurrence of several respiratory symptoms, nocturnal asthma, medication use, and restrictions in activity along with the use of gas stoves, wood stoves, fireplaces, and exposure to environmental tobacco smoke. Among this panel of relatively moderate to severe asthmatics, the respiratory irritants produced by several domestic combustion sources were associated with increased symptoms and morbidity.

Efforts to reduce downtown traffic congestion in Atlanta during the Olympic Games resulted in decreased traffic density. This was associated with a prolonged reduction in ozone pollution and significantly lower rates of childhood asthma events. During the Olympic Games, the number of asthma acute care events decreased 41.6%. This provides support for efforts to reduce air pollution and improve health via reductions in motor vehicle traffic.

Air pollution was found to be significantly and consistently correlated with acute asthma exacerbations, chest symptoms, and lung function decrements. The pollutant most consistently associated with adverse health consequences was ozone and the effects directly correlated with ozone concentration. Decrease in ozone indicated reductions in pulmonary problems. Studies have also indicated an increased risk of an asthma exacerbation and of experiencing chest symptoms of approximately 40% on the highest pollution day. Based on these reports, a rise in ozone is associated with an increase in the expected number of unscheduled medication administration and number of chest symptoms. Increases in asthma emergency room visits and hospitalizations correlated significantly with increased ozone.

Thus, air pollution can be a major contributor to the respiratory problems experienced by children with asthma. Decreased exposure to these pollutants or a better understanding of the processes by which they impact the airway may be useful in decreasing asthma severity.

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