air pollution and emergency department visits for headache and migraine

Background: associations between ambient air pollution and emergency department (ed) visits for headache and migraine were examined in a multi-city study during the period of april 2004 to december 2011 in nine cities across ontario, canada. objectives: evaluate potential positive associations between air pollution and ed visits for headache. materials and methods: data on ed visits for headache were retrieved from the national ambulatory care reporting system in canada. case-crossover design was used for this study for three diagnosis categories: migraine, headache-os (other specified, os) and headache-nos (not otherwise specified, nos). a time-stratified case-crossover technique was applied to investgate the associations of ed visits for headache with ambient air pollution. odds ratios (ors) and their corresponding 95% confidence intervals for ed visits associated with increased levels of air pollutants were calculated by applying conditional logistic regression. results: among females, statistically significant positive results were observed for one unit increase in inter-quartile range (iqr) of no2 (iqr = 9 ppb) for lag 0 days: or = 1.015 (1.000, 1.030) for migraine and for nos: for no2 for lags 0 to 2, where the highest result was for lag 0: or = 1.015 (1.005, 1.026), for so2 (iqr = 2.5 ppb) for lag 2: or = 1.012 (1.002, 1.021) and for pm2.5 for lags 1 and 2, or = 1.011 (1.002, 1.021) and or = 1.010 (1.000, 1.020) respectively among females. no significant statistically significant results were observed among males. conclusions: our findings support a number of statistically significant positive associations between air pollutants and the number of ed visits for headache and migraine.