Air pollution remains a major aggravation of respiratory symptoms and disease. Sulfur dioxide, ozone, sulfuric acid, particulate matter such as the fine particles from wood smoke, and nitrogen dioxide all produce significant effects when investigated in laboratory or field studies. These effects are decreases in pulmonary function and evidence of inflammation as well as suggestions of increases in chronic respiratory disease. Asthmatic subjects may be the group at greatest risk from air pollutants. Common medications used to treat asthma have varying effects on blocking or mitigating these pollutant-induced effects.