The impact of the environment on the upper respiratory tract of children has become an issue of recent interest. Sulfur dioxide causes nasal congestion in children as well as an increase in both mast cells and lymphocytes in nasal lavage fluids. Chlorpheniramine blocks the effect of sulfur dioxide on the nasal mucosa. Ozone exposure results in nasal congestion, increased levels of histamine, neutrophils, eosinophils, and mononuclear cells in nasal lavage fluid. No data are available on the effects of nitrogen dioxide or wood-burning stoves on the upper respiratory tracts of children. Formaldehyde in sufficient concentrations causes upper airway irritation; however, no data are available on its long-term effects. Detriments in air quality cause adverse changes in the lower respiratory tracts of susceptible individuals. The effects on the upper respiratory tract are more difficult to document. There may be a causal relationship, but definitive proof of whether air pollution results in significant increases in pediatric otitis media, sinusitis, rhinitis, and pharyngitis has yet to be demonstrated.