Effects of Heat and Cold Temperature on Cause-Specific Mortality between 1996 and 2010 in Ontario, Canada

Abstract

Effects of Heat and Cold Temperature on Cause-Specific Mortality between 1996 and 2010 in Ontario, CanadaAbstract Number:1841 Hong Chen*, Abderrahmane Yagouti, Richard Foty, Eric Lavigne, Richard Burnett, Mark Goldberg, Paul Villeneuve, Sabit Cakmak, John Wang, and Ray Copes Hong Chen* Public Health Ontario, Canada, E-mail Address: [email protected] Search for more papers by this author , Abderrahmane Yagouti Health Canada, Canada, E-mail Address: [email protected] Search for more papers by this author , Richard Foty Public Health Ontario, Canada, E-mail Address: [email protected] Search for more papers by this author , Eric Lavigne Health Canada, Canada, E-mail Address: [email protected] Search for more papers by this author , Richard Burnett Health Canada, Canada, E-mail Address: [email protected] Search for more papers by this author , Mark Goldberg McGill University, Canada, E-mail Address: [email protected] Search for more papers by this author , Paul Villeneuve Carleton University, Canada, E-mail Address: [email protected] Search for more papers by this author , Sabit Cakmak Health Canada, Canada, E-mail Address: [email protected] Search for more papers by this author , John Wang Public Health Ontario, Canada, E-mail Address: [email protected] Search for more papers by this author , and Ray Copes Public Health Ontario, Canada, E-mail Address: [email protected] Search for more papers by this author AbstractBACKGROUND: Extreme ambient temperature, especially heat, is associated with mortality; however, heat-related mortality risk has not been quantified systematically in Ontario, the largest province in Canada. Less is known about cold-related risk in this population. METHOD: This study comprised all residents of Ontario who died during 1996-2010 (1.3 million deaths). A time-stratified case-crossover analysis was applied to assess the relation between temperature change and cause-specific mortality (e.g., respiratory, myocardial infarction (MI), diabetes) for warm season (June to August) and cold season (Dec. to Feb.), separately, adjusting for selected meteorological factors, air pollutants, daily physician’s visits for influenza, and holidays. County-specific effect estimates were obtained first, and then pooled across Ontario. We examined various exposure metrics (e.g., apparent and air temperature) and lagged exposure periods (lag 1-6). We also assessed the effect of extreme heat and cold episodes, defined as daily mean temperature in the upper or lower 5th (or 1st) percentile of a county’s temperature distribution for 1, 2, or 3 consecutive days.RESULTS: A 5oC increase in mean daily apparent temperature in warm season was associated with a 1.5% increase in same-day deaths for nonaccidental causes (95% confidence interval (CI)=0.3%-2.7%) and a 3.6% increase for respiratory deaths (95%CI=0-7.5%) across Ontario. Extreme heat episodes were seen to increase respiratory deaths by 30% to 47% (depending on episode definitions), relative to other days. Cold-related mortality was most associated with exposure over a 6-day lag period, with a 3.1% increase in nonaccidental deaths (95%CI=1.8%-4.5%) and a 8.2% in MI-related deaths (95%CI=3.5%-13.2%) per 5oC decrease in apparent temperature. There was little evidence of increased risks with extreme cold episodes.CONCLUSIONS: Heat contributed to excess deaths in Ontario. There were also important mortality risks from cold.