Association between Fine Particulate Air Pollution and Daily Clinic Visits for Migraine in a Subtropical City: Taipei, Taiwan.

This study was undertaken to determine whether there was an association between fine particle (PM₂.₅) levels and daily clinic visits for migraine in Taipei, Taiwan. Daily clinic visits for migraine and ambient air pollution data for Taipei were obtained for the period from 2006-2011. The odds ratio of clinic visits was estimated using a case-crossover approach, controlling for weather variables, day of the week, seasonality, and long-term time trends. Generally, no significant associations between PM₂.₅ levels and migraine visits were observed on cool days. On warm days, however, for the single pollutant model (without adjustment for other pollutants), increased clinic visits for migraine were significantly associated with PM₂.₅ levels, with an interquartile range (IQR) rise associated with a 13% (95% CI = 8%-19%) elevation in number of migraine visits. In bi-pollutant model, PM₂.₅ remained significant after the inclusion of sulfur dioxide (SO₂) or ozone (O₃) on warm days. This study provides evidence that higher levels of PM₂.₅ increase the risk of clinic visits for migraine in Taipei, Taiwan.