Effects of photochemical air pollution and allergen exposure on upper respiratory tract inflammation in asthmatics.

Asthma is an inflammatory disease of the airways, and exacerbations of this disease have been associated with high levels of air pollution. The objective of this study was to examine whether ambient air pollution and/or allergen exposure induces inflammatory changes in the upper airways of asthmatics. Sixty patients with intermittent to severe persistent asthma visited the Hospital's Out Patient Clinic every 2 wk for a period of 3 mo, and on each visit a nasal lavage was obtained. Associations between nasal inflammatory parameters and seasonal allergens and/or air pollution exposures were analyzed using linear regression analysis. The study ran from July 3 to October 6, 1995, during which period ozone (8-h mean: 80 micrograms/m3) and PM10 (24-h mean: 40 micrograms/m3) were the major air pollutants; the major aeroallergen was mugwort pollen (24-h mean: 27 pollen grains/m3). Effects on both cellular and soluble markers in nasal lavage were demonstrated for both ozone and mugwort pollen, but not for PM10. Ambient ozone exposure was associated with an increase in neutrophils (112% per 100 micrograms/m3 increase in 8-h average ozone concentration), eosinophils (176%), epithelial cells (55%), IL-8 (22%), and eosinophil cationic protein (ECP) (19%). Increases in environmental mugwort pollen counts were associated with an increase in nasal eosinophils (107% per 100 pollen/m3) and ECP (23%), but not with neutrophils, epithelial cells, or lL-8. This study demonstrated that both ambient ozone and allergen exposure are associated with inflammatory responses in the upper airways of subjects with asthma, although the type of inflammation is qualitatively different.