Air Health Effects Research Section, Healthy Environments and Consumer Safety Branch, Health Canada, Ottawa, ON, Canada K1A OK9. mietek_szyszkowicz@hc-sc.gc.ca
A variety of environmental factors have been identified as possible triggers for migraine and other headache syndromes.
We analyzed associations between air pollution and emergency department (ED) visits for migraine and headache.
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.
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