Environmental air pollution and lung disease in children.

Acute exposure to air pollution is associated with increased respiratory symptoms and decreases in lung function in children. Respiratory symptoms in healthy children are usually nonspecific and not severe. Lower respiratory symptoms and extra use of bronchodilators will increase by about one-third with exposure to peak levels of ozone in children with asthma. Similarly, sulphates will increase the use of medication and decrease lung function in asthmatic children. Hospital and outpatient admissions for children with pre-existing asthma may be increased in the range of 20% with acute exposure to ambient ozone peaks and possibly with increased sulphur dioxide (SO2). Short-term nitrogen dioxide (NO2) exposure from indoor and outdoor sources has been associated with nonspecific respiratory symptoms and decreased lung function, again particularly in children with pre-existing asthma. No effect on hospital admissions has been documented. Chronic exposure to respirable particles, SO2 and NO2 is associated with up to three-fold increases in nonspecific chronic respiratory symptoms. Exposure to high traffic flow and, in particular, truck traffic and diesel exhaust leads to significant increases in respiratory symptoms and decreases in lung function, while no clear effect on the inception of asthma has been documented. It appears unlikely that long-term exposure to pollutants or irritants is responsible for the increase in asthma and allergy observed in many countries. However, although the effect of air pollution is small in most children, it has a significant influence on the health of children with pre-existing lung disease. Owing to the large number of individuals exposed this results in a considerable burden for the health system.