Allergic Rhinitis: Association with Air Pollution and Weather Changes, and Comparison with That of Allergic Conjunctivitis in Taiwan

Allergic conjunctivitis (AC) and rhinitis (AR) are common allergic diseases that may be environmentally related. We used a systematic sampling cohort database, which was applied in an AC study previously, to examine the association of AR with air pollution and weather changes. A case-crossover design coupled with conditional logistic analysis was implemented in the analysis; we identified 140,365 eligible AR subjects, and matched their diagnoses with environmental monitoring data. Unlike AC, the descriptive statistics indicated that AR occurred the most in adults under 50 years old by age (44.7%), and in winter by season (28.7%) (p < 0.001); similar to AC, AR occurred more in women than to men. Nitrogen dioxide (NO2) was found to be positively associated with AR (p < 0.001), whereas relative humidity and temperature were negatively related (p < 0.001). We found that the risk of AR increased with descending NO2 levels relative to AC (OR = 0.984, p = 0.003) after adjustment for covariates. It is suggested that AR could be triggered or exacerbated by lower levels of NO2 than is AC. We recommend that AR patients pay extra attention to air pollution and mitigate their allergic problem accordingly.