Asthma is an important public health challenge. The objective of this research was to investigate the relationship of air pollution and weather to adolescent asthma prevalence and attack rate. A 6-month mass screening asthma study was conducted from October 1995 to March 1996 in Taiwan. The study population included junior high school students from throughout the country (1,139,452 students). Eighty-nine percent of students completed questionnaires (International Study of Asthma and Allergies in Childhood-ISAAC and New England Core Questionnaires) and passed a logical screening error program. Lung function data was collected to assist in the diagnosis of asthma status. From the students screened during this mass survey, a stratified random sample of 64,660 students was analyzed for asthma prevalence and attack rate. Using a regression model to compare the USEPA National Ambient Air Quality Standards 2000 (NAAQS, 2000) to asthma prevalence, this investigation found that the standards may not provide enough protection for adolescents after controlling for age, rhinitis, eczema, urban birth location, parental education level, exercise, cigarette smoking, environmental tobacco smoking, alcohol beverage consumption and weather factors. The general estimating equations (GEE) model, a repeated measurement regression model, was used to examine the relationship between the monthly asthma attack rate among asthma patients and air pollution (nitrogen oxides; nitrogen dioxide; nitric oxide; Ozone; PM10) while controlling for household smoking. The GEE model demonstrated that air pollution is related to asthma attack rate. Air pollution factors also interacted with weather parameters when related to asthma attack rate.