Air pollution and daily ED visits for migraine and headache in Edmonton, Canada.
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.
Szyszkowicz
Mieczyslaw
M
Air Health Effects Research Section, Healthy Environments and Consumer Safety Branch, Health Canada, Ottawa, ON, Canada K1A OK9. mietek_szyszkowicz@hc-sc.gc.ca
Stieb
David M
DM
Rowe
Brian H
BH
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000393:Air Pollutants / Q000009:adverse effects / Q000032:analysis; D000397:Air Pollution / Q000009:adverse effects*; D000416:Alberta / Q000453:epidemiology; D004636:Emergency Service, Hospital / Q000706:statistics & numerical data*; D005260:Female; D006261:Headache / Q000453:epidemiology* / Q000209:etiology; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D008881:Migraine Disorders / Q000453:epidemiology* / Q000209:etiology; D012189:Retrospective Studies; D012307:Risk Factors; D012621:Seasons; D014887:Weather
D000393:Air Pollutants