Association between air pollution and daily consultations with general practitioners for allergic rhinitis in London, United Kingdom.

Few published studies have looked at the health effects of air pollution in the primary care setting, and most have concentrated on lower rather than upper respiratory diseases. The authors investigated the association of daily consultations with general practitioners for allergic rhinitis with air pollution in London, United Kingdom. Generalized additive models were used to regress time series of daily numbers of patients consulting for allergic rhinitis against 1992--1994 measures of air pollution, after control for possible confounders and adjustment for overdispersion and serial correlation. In children, a 10th--90th percentile increase in sulfur dioxide (SO(2)) levels 4 days prior to consultation (13-31 microg/m(3)) was associated with a 24.5% increase in consultations (95% confidence interval: 14.6, 35.2; p < 0.00001); a 10th--90th percentile increase in averaged ozone (O(3)) concentrations on the day of consultation and the preceding 3 days (6--29 parts per billion) was associated with a 37.6% rise (95% confidence interval: 23.3, 53.5; p < 0.00001). For adults, smaller effect sizes were observed for SO(2) and O(3). The association with SO(2) remained highly significant in the presence of other pollutants. This study suggests that air pollution worsens allergic rhinitis symptoms, leading to substantial increases in consultations. SO(2) and O(3) seem particularly responsible, and both seem to contribute independently.