All-cause mortality and long-term exposure to low level air pollution in the '45 and up study' cohort, Sydney, Australia, 2006-2015

Ivan C Hanigan; Margaret I Rolfe; Luke D Knibbs; Farhad Salimi; Christine T Cowie; Jane Heyworth; Guy B Marks; Yuming Guo; Martin Cope; Adrian Bauman; Bin Jalaludin; Geoffrey G Morgan

doi:10.1016/j.envint.2019.02.044

All-cause mortality and long-term exposure to low level air pollution in the '45 and up study' cohort, Sydney, Australia, 2006-2015

Environ Int. 2019 May:126:762-770. doi: 10.1016/j.envint.2019.02.044. Epub 2019 Mar 15.

Authors

Ivan C Hanigan¹, Margaret I Rolfe², Luke D Knibbs³, Farhad Salimi⁴, Christine T Cowie⁵, Jane Heyworth⁶, Guy B Marks⁷, Yuming Guo⁸, Martin Cope⁹, Adrian Bauman¹⁰, Bin Jalaludin¹¹, Geoffrey G Morgan⁴

Affiliations

¹ Centre for Air Pollution, Energy and Health Research, Australia; The University of Sydney, University Centre for Rural Health, School of Public Health, Sydney, Australia; Centre for Research and Action in Public Health, University of Canberra, Canberra, Australia. Electronic address: ivan.hanigan@sydney.edu.au.
² The University of Sydney, University Centre for Rural Health, School of Public Health, Sydney, Australia.
³ Centre for Air Pollution, Energy and Health Research, Australia; School of Public Health, The University of Queensland, Herston, Australia.
⁴ Centre for Air Pollution, Energy and Health Research, Australia; The University of Sydney, University Centre for Rural Health, School of Public Health, Sydney, Australia.
⁵ Centre for Air Pollution, Energy and Health Research, Australia; South West Sydney Clinical School, University of NSW, Australia; Ingham Institute for Applied Medical Research, Woolcock Institute of Medical Research, The University of Sydney, Sydney, Australia.
⁶ Centre for Air Pollution, Energy and Health Research, Australia; The Clean Air and Urban Landscapes Hub & School of Population and Global Health, The University of Western Australia, Australia.
⁷ Centre for Air Pollution, Energy and Health Research, Australia; Woolcock Institute of Medical Research & South West Sydney Clinical School, University of New South Wales, Sydney, Australia.
⁸ Centre for Air Pollution, Energy and Health Research, Australia; Department of Epidemiology and Preventive Medicine, School of Public Health and Preventive Medicine, Monash University, Melbourne, Australia.
⁹ Centre for Air Pollution, Energy and Health Research, Australia; CSIRO, Melbourne, Australia.
¹⁰ The University of Sydney, School of Public Health, Sydney, Australia.
¹¹ Centre for Air Pollution, Energy and Health Research, Australia; Woolcock Institute of Medical Research, University of Sydney, Sydney, Australia; School of Public Health and Community Medicine, University of New South Wales & Ingham Institute for Applied Medical Research, Sydney, Australia.

PMID: 30878871
DOI: 10.1016/j.envint.2019.02.044

Abstract

Background: Epidemiological studies show that long-term exposure to ambient air pollution reduces life expectancy. Most studies have been in environments with relatively high concentrations such as North America, Europe and Asia. Associations at the lower end of the concentration-response function are not well defined.

Objectives: We assessed associations between all-cause mortality and exposure to annual average particulate matter <2.5 μm (PM_2.5) and nitrogen dioxide (NO₂) in Sydney, Australia, where concentrations are relatively low.

Methods: The '45 and Up Study' comprises a prospective longitudinal cohort from the state of New South Wales, Australia with 266,969 participants linked to death registry data. We analyzed data for the participants who resided in Sydney at baseline questionnaire (n = 75,268). Exposures to long-term pollution were estimated using annual averages from a chemical transport model (PM_2.5), and a satellite-based land-use regression model (NO₂). Socio-demographic information was extracted from the baseline questionnaire. Cox proportional hazard models were applied to estimate associations, while adjusting for covariates.

Results: In our cohort mean annual PM_2.5 was 4.5 μg/m³ and mean NO₂ was 17.8 μg/m³. The mortality rate was 4.4% over the 7 years of follow up. Models that adjusted for individual-level and area-level risk factors resulted in a detrimental non statistically significant hazard ratio (HR) of 1.05 (95% CI: 0.98-1.12) per 1 μg/m³ increase in PM_2.5, and 1.03 (95% CI: 0.98-1.07) per 5 μg/m³ increase in NO₂.

Conclusions: We found evidence that low-level air pollution exposure was associated with increased risk of mortality in this cohort of adults aged 45 years and over, even at the relatively low concentrations seen in Sydney. However, a clear determination of the association with mortality is difficult because the results were sensitive to some covariates. Our findings are supportive of emerging evidence that exposure to low levels of air pollution reduces life expectancy.

Keywords: All-cause mortality; Fine particulate matter; Gaseous pollutants; Low concentration; Survival model.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Aged
Aged, 80 and over
Air Pollutants / adverse effects*
Air Pollution / adverse effects*
Environmental Exposure / adverse effects*
Female
Humans
Longitudinal Studies
Male
Middle Aged
Mortality*
New South Wales / epidemiology
Prospective Studies
Risk Assessment

Substances

Air Pollutants