Ambient air pollution and risk for ischemic stroke and transient ischemic attack.
OBJECTIVE
Data on the association between air pollution and cerebrovascular disease in the United States are limited. The objective of this study was to investigate the association between short-term exposure to ambient air pollution and risk for ischemic cerebrovascular events in a US community.


METHODS
Daily counts of ischemic strokes/transient ischemic attacks (TIAs) (2001-2005) were obtained from the population-based Brain Attack Surveillance in Corpus Christi (BASIC) Project. Daily particulate matter less than 2.5microm in diameter (PM(2.5)), ozone (O(3)), and meteorological data were obtained from Texas Commission on Environmental Quality. To examine the association between PM(2.5) and stroke/TIA risk, we used Poisson regression. Separate models included same-day PM(2.5), PM(2.5) lagged 1 to 5 days, and an averaged lag effect. All models were adjusted for temperature, day of week, and temporal trends in stroke/TIA. The effects of O(3) were also investigated.


RESULTS
Median PM(2.5) was 7.0microg/m(3) (interquartile range, 4.8-10.0microg/m(3)). There were borderline significant associations between same-day (relative risk [RR], 1.03; 95% confidence interval [CI], 0.99-1.07 for an interquartile range increase in PM(2.5)) and previous-day (RR, 1.03; 95% CI, 1.00-1.07) PM(2.5) and stroke/TIA risk. These associations were independent of O(3), which demonstrated similar associations with stroke/TIA risk (same-day RR, 1.02; 95% CI, 0.97-1.08; previous-day RR, 1.04; 95% CI, 0.99-1.09).


CONCLUSIONS
We observed associations between recent PM(2.5) and O(3) exposure and ischemic stroke/TIA risk even in this community with relatively low pollutant levels. This study provides data on environmental exposures and stroke risk in the United States, and suggests future research on ambient air pollution and stroke is warranted.
Department of Epidemiology, University of Michigan School of Public Health, Ann Arbor, MI 48109-2029, USA. llisabet@umich.edu
Lynda D
LD
Lisabeth
James D
JD
Escobar
J Timothy
JT
Dvonch
Brisa N
BN
Sánchez
Jennifer J
JJ
Majersik
Devin L
DL
Brown
Melinda A
MA
Smith
Lewis B
LB
Morgenstern
D000368:Aged; D000369:Aged, 80 and over; D000393:Air Pollutants / Q000009:adverse effects*; D002545:Brain Ischemia / Q000453:epidemiology*; D015984:Causality; D015331:Cohort Studies; D005260:Female; D006801:Humans; D002546:Ischemic Attack, Transient / Q000453:epidemiology*; D008297:Male; D008875:Middle Aged; D010126:Ozone / Q000009:adverse effects; D011159:Population Surveillance; D012044:Regression Analysis; D012307:Risk Factors; D020521:Stroke / Q000453:epidemiology*; D013781:Texas / Q000453:epidemiology
D000393:Air Pollutants; D010126:Ozone