THE ROLE OF AIR POLLUTANTS IN ADOLESCENT ASTHMA

Abstract

Asthma, being a multifactorial disease, is aggravated by many environmental agents as discussed in this issue. Since the common air pollutants (ozone, particulate matter, nitrogen dioxide, and sulfur dioxide) are known respiratory irritants, it is not surprising that they all aggravate asthma. Wardlaw has listed some possible mechanisms for interactions between air pollution and asthma: direct effect on hypersensitive airways; increase in nonspecific bronchial hyperresponsiveness; direct toxic effect; and modification of the immune system.51 There is an extensive literature describing the relationship between common outdoor air pollutants and respiratory disease. Included are many studies of the associations between air pollutants and hospital emergency department visits and hospital admissions for diagnoses of asthma and a few controlled exposure studies. Several recent summaries are available.41, 48, 49, 50 According to Bates5 associations between indices of health effects and air pollutants indicate that pollutants probably play a role in the worsening of asthma. He suggests further that hospital admissions are likely to be a more sensitive indicator of asthma status than is mortality. Is there evidence that adolescents with asthma are more sensitive to environmental challenges than adults or children? Most of the epidemiologic time series studies of hospital events do not stratify data by age. Thus there is not a large literature base covering the adverse effects of air pollutants on adolescents with asthma. To give the reader an overview of what is known about air pollutant exposure to adolescents with asthma, I will review two data bases: (1) Controlled human studies (2) Epidemiologic studies(a) Hospital emergency department and admissions studies (b) Panel studies using diaries and peak flow meters