Environmental Air Pollution and Acute Cerebrovascular Complications: An Ecologic Study in Tehran, Iran

Background: in this study, we aimed to assess the associationbetween air pollution and cerebrovascular complications in tehran,one of the most air-polluted cities in the world, among differentsubgroups of patients with stroke in 2004.methods: in this ecologic study, we calculated the daily averagelevels of different air pollutants including co, nox, so2, o3, andpm10 and also humidity and temperature on the day of stroke and 48hours prior to stroke in 1 491 patients admitted with the diagnosis ofstroke in eight referral hospitals in different areas of tehran. then,we evaluated the association between the rate of stroke admissionsand the level of the selected pollutants, humidity, and temperatureon the day of stroke and 48 hours prior to stroke among differentsubgroups of patients.results: there was no significant association between the samedaylevel of the pollutants and the rate of stroke admissions, but anassociation was seen for their level 48 hours before stroke. theseassociations differed among different subgroups of age, sex, historyof underlying diseases, and type of stroke. same-day temperaturehad a reverse association in patients with hemorrhagic stroke andin patients without a history of heart disease or previous stroke. adirect significant association was seen for humidity level 48 hoursbefore stroke in patients with a history of heart disease.conclusions: it is inferred that air pollution has a direct associationwith the incidence of stroke and these association differs amongdifferent subgroups of patients. the results of this study are nottime-dependant and can be generalized to different times andregions. moreover, these results may be useful for environmentalhealth policy makers.