Background: A variety of environmental factors have been identified as possible triggers for migraine and other headache syndromes.
Objective: We analyzed associations between air pollution and emergency department (ED) visits for migraine and headache.
Methods: Analysis was based on 56,241 ED visits for migraine and 48,022 ED visits for headache to Edmonton hospitals between 1992 and 2002. A Poisson model of counts hierarchically clustered by day of week, month, and year was applied using generalized linear mixed models. Temperature and relative humidity were included as covariates.
Results: Females accounted for 78.5% of migraine visits and 56.3% of headache visits. An interquartile range (IQR) increase (6.2 microg/m3) in daily average particulate matter of median aerodynamic diameter less than 2.5 microm (PM2.5) was associated with increases in visits of 3.3% for migraine (95% confidence interval [CI]: 0.6-6.0), lagged 2 days, and 3.4% for headache (95% CI: 0.3-6.6), lagged 0 days, among females in the cold season (October-March). PM2.5 was also associated with cold season migraine visits among females at lag 0 and 1 day (P < .1). In the warm period (April-September), a 2.3-ppb IQR increase in sulfur dioxide was associated with a 2.5% increase in migraine visits (95% CI: 0.3-4.6) among females, whereas a 12.8-ppb IQR increment in nitrogen dioxide was associated with a 6.8% increase in headache visits (95% CI: 1.5-12.5) for males.
Conclusions: Findings provide preliminary evidence of an association between air pollution and ED visits for migraine and nonspecific headache. Findings were most consistent for particulate matter.