Ambient air pollution and daily emergency department visits for headache in Ottawa, Canada

Background.— No extensive studies exist on the relation between ambient air pollution and health outcomes such as migraine or headache. From other side, existing publications indicated that air pollutants can trigger migraine or headache.
Objective.— To examine associations between emergency department (ED) visits for headache and environmental conditions: ambient air pollution concentrations adjusted for weather factors (atmospheric pressure, temperature, and relative humidity).
Design and Methods.— This is a time-series study of 8012 ED visits for headache (International Classification for Diseases ninth revision: 784) recorded at an Ottawa hospital between 1992 and 2000. The generalized linear mixed models technique is used to model relation between daily counts of ED visits for headache and ambient air pollutants (gases: sulphur dioxide SO₂], nitrogen dioxide NO₂], carbon monoxide CO]). The counts of visits for all patients, male and female patients, are analyzed separately.
Results.— The percentage increase in daily ED visits for headache was 4.2% (95% CI: 0.2, 6.4) and 4.9% (95% CI: 1.2, 8.8) for 1-day and 2-day lagged exposure to SO₂ for an increase in the interquartile range (IQR, IQR = 3.9 ppb). The positive statistically significant associations were also observed for exposure to NO₂ and CO for all and male ED visits for headache.
Conclusions.— Presented findings provide support for the hypothesis that ED visits for headache are related to ambient air pollution.