Abstract
BACKGROUND: Several studies have reported associations between long term exposure to air pollutants and cause-specific mortality. However, since the concentrations of air pollutants in Asia are much higher compared to those reported in North American and European cohort studies, cohort studies on long term effects of air pollutants in Asia are needed for disease burden assessment and to inform policy.
OBJECTIVES: To assess the effects of long-term exposure to particulate matter with aerodynamic diameter < 2.5 μm (PM 2.5), black carbon (BC) and nitrogen dioxide (NO 2) on cause-specific mortality in an elderly cohort in Hong Kong.
METHODS: In a cohort of 66,820 participants who were older than or equal to 65 years old in Hong Kong from 1998 to 2011, air pollutant concentrations were estimated by land use regression and assigned to the residential addresses of all participants at baseline and for each year during a 11 year follow up period. Hazard ratios (HRs) of cause-specific mortality (including all natural cause, cardiovascular and respiratory mortality) associated with air pollutants were estimated with Cox models, including a number of personal and area-level socioeconomic, demographic, and lifestyle factors.
RESULTS: The median concentration of PM 2.5 during the baseline period was 42.2 μg/m 3 with an IQR of 5.5 μg/m 3, 12.1 (9.6) μg/m 3 for BC and 104 (25.6) μg/m 3 for NO 2. For PM 2.5, adjusted HR per IQR increase and per 10 μg/m 3 for natural cause mortality was 1.03 (95%CI: 1.01, 1.06) and 1.06 (95%CI: 1.02, 1.11) respectively. The corresponding HR were 1.06 (95%CI: 1.02, 1.10) and 1.01 (95%CI: 0.96, 1.06) for cardiovascular disease and respiratory disease mortality, respectively. For BC, the HR of an interquartile range increase for all natural cause mortality was 1.03 (95%CI: 1.00, 1.05). The corresponding HR was 1.07 (95%CI: 1.03, 1.11) and 0.99 (95%CI: 0.94, 1.04) for cardiovascular disease and respiratory disease mortality. For NO 2, almost all HRs were approximately 1.0, except for IHD (ischemic heart disease) mortality.
CONCLUSION: Long-term exposure to ambient PM 2.5 and BC was associated with an elevated risk of cardiovascular mortality. Despite far higher air pollution exposure concentrations, HRs per unit increase in PM 2.5 were similar to those from recent comparable studies in North America.
Original language | English |
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Pages (from-to) | 99-106 |
Number of pages | 8 |
Journal | Environment international |
Volume | 117 |
Early online date | 3 May 2018 |
DOIs | |
Publication status | Published - 1 Aug 2018 |
Bibliographical note
Copyright © 2018. Published by Elsevier Ltd.Funding
This work was supported by the Health Effects Institute , Boston, USA under Research Agreement 4941-RFA13-1 . The authors declare they have no actual or potential competing financial interests. Appendix A
Keywords
- Air pollution
- Cohort study
- Hong Kong
- Mortality
- Respiratory Tract Diseases/mortality
- Cardiovascular Diseases/mortality
- Humans
- Environmental Exposure/analysis
- Aged
- Air Pollution
- Hong Kong/epidemiology
- Cohort Studies