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The Air Quality Health Index as a predictor of emergency department visits for ischemic stroke in Edmonton, Canada

Journal of Exposure Science & Environmental Epidemiology volume 24, pages 358–364 (2014)Cite this article

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Abstract

The Air Quality Health Index (AQHI) is an aggregate measure of outdoor air quality. We investigated associations between the AQHI and emergency department (ED) visits for acute ischemic stroke to validate the AQHI as a predictor of risk of morbidity from stroke. ED visits in Edmonton, Canada between 1998 and 2002 were linked to hourly AQHI values and concentrations of carbon monoxide (CO), nitrogen dioxide (NO2), ozone, particulate matter with aerodynamic diameter less than 2.5 and 10 μm, and sulfur dioxide. A time-stratified case-crossover analysis was employed, and measures of association were adjusted for temperature and relative humidity. The AQHI, NO2 and CO were positively associated with the number of ED visits for ischemic stroke during April–September, and associations were strongest for persons 75 years of age and older. In this age range, the odds ratios (95% confidence intervals) for an interquartile range increase of AQHI in 1–24 h, 25–48 h, and 1–72 h lag periods were 1.23 (1.08–1.40), 1.15 (1.01–1.31), and 1.30 (1.10–1.54), respectively. Significant positive associations were also observed for NO2 and CO. Our finding that ED visits for stroke were significantly associated with the AQHI suggests that the AQHI may be a valid communication tool for air pollution morbidity effects related to stroke.

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Acknowledgements

We thank Environment Canada for providing the air pollution data from the NAPS network. We also expresses our appreciation to Chris Houston from Information Services, in the former Capital Health Authority (now Alberta Health Services), and Virginia Willis, from the Emergency Medicine Research Group (EMeRG) for securing these data as well as to Health Canada for funding the data acquisition. Dr. Rowe is supported through a Tier I Canada Research Chair in Evidence-based Emergency Medicine from the Canadian Institutes for Health Research (CIHR) through the Government of Canada (Ottawa, Canada). The study was funded by Health Canada.

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Authors and Affiliations

  1. Population Studies Division, Healthy Environments and Consumer Safety Branch, Health Canada, 200 Eglantine Driveway, 1915B, Ottawa, K1A 0K9, Ontario, Canada

    Li Chen, Paul J Villeneuve & Ling Liu

  2. Department of Health Sciences, Carleton University, Ottawa, K1S 5B6155, Ontario, Canada

    Paul J Villeneuve

  3. Department of Emergency Medicine and School of Public Health, University of Alberta, Emergency Operational Clinical Network, Alberta Health Services, University of Alberta Hospital, Edmonton, T6G 2B7, Alberta, Canada

    Brian H Rowe

  4. Population Studies Division, Healthy Environments and Consumer Safety Branch, Health Canada, 4595 Canada Way, Burnaby, V5G 1J9, British Columbia, Canada

    David M Stieb

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  1. Li Chen
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Correspondence to Li Chen.

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Chen, L., Villeneuve, P., Rowe, B. et al. The Air Quality Health Index as a predictor of emergency department visits for ischemic stroke in Edmonton, Canada. J Expo Sci Environ Epidemiol 24, 358–364 (2014). https://doi.org/10.1038/jes.2013.82

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