title: Associations of acute exposure to fine and coarse particulate matter and mortality among older people in Tokyo, Japan.
abstract: Recent studies have reported adverse health effects of short-term exposure to coarse particles independent of particulate matter less than 2.5 μm in diameter (PM2.5), but evidence in Asian countries is limited. We therefore evaluated associations between short-term exposure to particulate matter (PM) and mortality among older people in Tokyo, Japan. We used a time-stratified, case-crossover design. Study participants included 664,509 older people (≥65 years old) in the 23 urbanized wards of the Tokyo Metropolitan Government, who died between January 2002 and December 2013. We obtained PM2.5 and suspended particulate matter (SPM; PM<7 μm in diameter) from one general monitoring station. We calculated PM7-2.5 by subtracting PM2.5 from SPM to account for coarse particles. We then used conditional logistic regression to estimate odds ratios (ORs) and 95 confidence intervals (CIs). Same-day PM2.5 and PM7-2.5 were independently associated with all-cause and cause-specific mortality related to cardiovascular and respiratory diseases; for example, both pollutants were positively associated with increased risk of all-cause mortality even after simultaneous adjustment for each pollutant: OR of 1.006 (95% CI: 1.003, 1.009) for PM2.5 and 1.016 (95% CI: 1.011, 1.022) for PM7-2.5. Even below concentrations stipulated by the Japanese air quality guidelines for PM2.5 and SPM (PM7), we observed adverse health effects. This study provides further evidence that acute exposure to PM2.5 and coarse particles is associated with increased risk of mortality among older people. Rigorous evaluation of air quality guidelines for daily average PM2.5 and larger particles should be continued.
authors.affiliation: Department of Human Ecology, Graduate School of Environmental and Life Science, Okayama University, 3-1-1 Tsushima-naka, Kita-ku, Okayama 700-8530, Japan. Electronic address: yorichan@md.okayama-u.ac.jp.
authors.forename: Takashi
authors.initials: T
authors.lastname: Yorifuji
authors.affiliation: Department of Public Health and Health Policy, Institute of Biomedical and Health Sciences, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8551, Japan. Electronic address: white-eye@hiroshima-u.ac.jp.
authors.forename: Saori
authors.initials: S
authors.lastname: Kashima
authors.affiliation: Department of Epidemiology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, 2-5-1 Shikata-cho, Kita-ku, Okayama 700-8558, Japan. Electronic address: h-doi@md.okayama-u.ac.jp.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Doi
mesh_terms: D000368:Aged; D000393:Air Pollutants / Q000032:analysis*; D000397:Air Pollution / Q000706:statistics & numerical data*; D018592:Cross-Over Studies; D004781:Environmental Exposure / Q000032:analysis* / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D008297:Male; D009026:Mortality / Q000639:trends*; D052638:Particulate Matter / Q000032:analysis*; D013997:Time Factors; D014041:Tokyo
chemical_list: D000393:Air Pollutants; D052638:Particulate Matter
keywords: Air pollution; Cardiovascular disease; Epidemiology; Mortality; Particulate matter; Respiratory disease