Abstract:
Asthma is a clinical syndrome characterized by airway hyperactivity leading to episodes of reversible airway constriction. Symptoms manifest clinically as shortness of breath, cough, chest tightness, and wheezing and can be treated with a variety of medications. Risk factors for the development of childhood asthma include a family history of atopy (i.e., an allergic tendency as indicated by a family history of asthma, hayfever, and/or eczema), other genetic factors such as race and gender, age, maternal cigarette smoking, low socioeconomic status, and a history of respiratory infections (Task Force on Asthma and Allergies in Communities with Increased Prevalence, 1998.) In susceptible children environmental agents can trigger episodes of asthma exacerbation. Evidence now indicates that components of air pollution, and specifically vehicular air pollution, may represent such environmental agents.
Vehicular pollution contains a mixture of carbon monoxide, formaldehyde, nitrogen oxides, sulfur oxides, hydrocarbons, ash, transition metals, and particulates. Ozone is produced as a reaction of nitrogen oxides with sunlight. Controlled studies with human volunteers have shown evidence of bronchoconstriction with exposures to nitrogen oxides, sulfur oxides, and ozone (Linn, 1983; Linn, 1986; Orehek, 1976). Bronchoconstriction was especially evident in those with pre-existing asthma.