Satellite-based estimates of long-term exposure to fine particles and association with mortality in elderly Hong Kong residents

Research output: Contribution to journalArticlepeer-review


  • Chit Ming Wong
  • Hak Kan Lai
  • Hilda Tsang
  • Thuan Quoc Thach
  • King Pan Chan
  • Lin Yang
  • Alexis K H Lau
  • Jon G Ayres
  • Siu Yin Lee
  • Wai Man Chan
  • Anthony J Hedley
  • Tai Hing Lam

Colleges, School and Institutes


BACKGROUND: A limited number of studies on long-term effects of particulate matter with aerodynamic diameter < 2.5 μm (PM2.5) on health suggest it can be an important cause of morbidity and mortality. In Asia where air quality is poor and deteriorating, local data on long-term effects of PM2.5 to support policy on air quality management are scarce.

OBJECTIVES: We assessed long-term effects of PM2.5 on the mortality in a single Asian city.

METHODS: For 10-13 years, we followed up a cohort of 66,820 participants ≥ 65 years of age who were enrolled and interviewed in all 18 Elderly Health Centres of the Department of Health, Hong Kong, in 1998-2001. Their residential addresses were geocoded into x- and y-coordinates, and their proxy exposures to PM2.5 at their addresses in 1 × 1 km grids were estimated from the U.S. National Aeronautics and Space Administration (NASA) satellite data. We used Cox regression models to calculate hazard ratios (HRs) of mortality associated with PM2.5.

RESULTS: Mortality HRs per 10-μg/m3 increase in PM2.5 were 1.14 (95% CI: 1.07, 1.22) for all natural causes, 1.22 (95% CI: 1.08, 1.39) for cardiovascular causes, 1.42 (95% CI: 1.16, 1.73) for ischemic heart disease, 1.24 (95% CI: 1.00, 1.53) for cerebrovascular disease, and 1.05 (95% CI: 0.90, 1.22) for respiratory causes.

CONCLUSIONS: Our methods in using NASA satellite data provide a readily accessible and affordable approach to estimation of a sufficient range of individual PM2.5 exposures in a single city. This approach can expand the capacity to conduct environmental accountability studies in areas with few measurements of fine particles.

CITATION: Wong CM, Lai HK, Tsang H, Thach TQ, Thomas GN, Lam KB, Chan KP, Yang L, Lau AK, Ayres JG, Lee SY, Chan WM, Hedley AJ, Lam TH. 2015. Satellite-based estimates of long-term exposure to fine particles and association with mortality in elderly Hong Kong residents. Environ Health Perspect 123:1167-1172;


Original languageEnglish
Pages (from-to)1167-72
Number of pages6
JournalEnvironmental Health Perspectives
Issue number11
Publication statusPublished - Nov 2015

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