The association between long-term exposure to low-level PM2.5 and mortality in the state of Queensland, Australia: A modelling study with the difference-in-differences approach

• Published in: PLoS medicine Vol. 17; no. 6; p. e1003141
• Main Authors: Yu, Wenhua, Guo, Yuming, Shi, Liuhua, Li, Shanshan
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 01.06.2020; Public Library of Science (PLoS)
• Subjects: Age Factors; Aged; Air pollution; Air quality measurements; Airborne particulates; Biology and Life Sciences; Cardiovascular diseases; Cardiovascular Diseases - mortality; Cause of Death; Disease prevention; Earth Sciences; Ecology and Environmental Sciences; Epidemiology; Female; Health care; Humans; Inhalation Exposure - adverse effects; Inhalation Exposure - statistics & numerical data; Investigations; Male; Medicine and Health Sciences; Middle Aged; Models, Statistical; Mortality; Observational studies; Outdoor air quality; Particulate matter; Particulate Matter - adverse effects; People and Places; Physical Sciences; Population; Preventive medicine; Public health; Queensland - epidemiology; Research and Analysis Methods; Respiratory Tract Diseases - mortality; Risk Factors; Software; Supervision; Temporal variations; Queensland; Melbourne Victoria Australia; Queensland Australia; Australia; United States > US; China
• ISSN: 1549-1676; 1549-1277; 1549-1676
• DOI: 10.1371/journal.pmed.1003141

To date, few studies have investigated the causal relationship between mortality and long-term exposure to a low level of fine particulate matter (PM2.5) concentrations. We studied 242,320 registered deaths in Queensland between January 1, 1998, and December 31, 2013, with satellite-retrieved annual average PM2.5 concentrations to each postcode. A variant of difference-in-differences (DID) approach was used to investigate the association of long-term PM2.5 exposure with total mortality and cause-specific (cardiovascular, respiratory, and non-accidental) mortality. We observed 217,510 non-accidental deaths, 133,661 cardiovascular deaths, and 30,748 respiratory deaths in Queensland during the study period. The annual average PM2.5 concentrations ranged from 1.6 to 9.0 μg/m3, which were well below the current World Health Organization (WHO) annual standard (10 μg/m3). Long-term exposure to PM2.5 was associated with increased total mortality and cause-specific mortality. For each 1 μg/m3 increase in annual PM2.5, we found a 2.02% (95% CI 1.41%-2.63%; p < 0.01) increase in total mortality. Higher effect estimates were observed in Brisbane than those in Queensland for all types of mortality. A major limitation of our study is that the DID design is under the assumption that no predictors other than seasonal temperature exhibit different spatial-temporal variations in relation to PM2.5 exposure. However, if this assumption is violated (e.g., socioeconomic status [SES] and outdoor physical activities), the DID design is still subject to confounding. Long-term exposure to PM2.5 was associated with total, non-accidental, cardiovascular, and respiratory mortality in Queensland, Australia, where PM2.5 levels were measured well below the WHO air quality standard.