Abstract of the research proposal:
The global burden of disease (GBD) attributable to air pollution is significant, representing 7.5% of all global mortality (n = 4 million deaths annually), with much of the world, especially those within low-and-middle-income nations subject to levels of outdoor air pollution in excess of World Health Organization guidelines. This means that exposure to outdoor air pollution may be among the most important modifiable risk factors for human health and global disease burden. However, substantial uncertainty remains regarding the true burden of disease across the globe. Historically, the bulk of air pollution studies have been performed in North America and Europe, from which the health effects of air pollution have generally been identified and been the basis for major policy efforts. By contrast, the largest global impacts of air pollution are estimated to occur from cardiovascular, malignant, and non-malignant respiratory disease in Asia, where current outdoor air pollution levels are typically higher than those in North American and Europe. However, relatively few epidemiological studies of long-term air pollution exposure have been performed in Asia. As it is uncertain whether the often-linear associations found in relatively low pollution areas extend to the higher Asian pollution levels, an Integrated Exposure Response function is used in the GBD assessment, which combines air pollution, passive and active smoking to inform the shape of the concentration response function (CRF). Several assumptions are made in the development of this function and future adaptation of the CRF based on actual cohort studies at higher levels of exposure would be invaluable. Further, the social and economic disparities between many Asian nations and those in North America and Europe mean that many of the previous studies of the health effects of air pollution may be of limited generalizability to the Asian population.
This proposal will address this knowledge gap by investigating the association between residential air pollution and natural cause and cause-specific (including cardio-respiratory, and lung cancer mortality) by applying satellite derived estimates of ambient PM2.5 and NO2 (supplemented with fine scale land use data) to the residential information of study participants of pooled prospective studies within the Asia Cohort Consortium (ACC). The ACC is a large-scale multi-center organization with the aim of merging and analyzing prospective cohorts across Asia. The ACC has a pooled dataset of 23 well-characterized cohort studies, totaling over 1 million participants, spread across seven Asian countries: India, Bangladesh, Korea, Taiwan, China, Singapore, and Japan. Geocoding the residential information of cohort participants will allow the estimation of ambient PM2.5 via satellite derived estimates performed by the Atmospheric Composition Analysis Group at a spatial resolution of approximately 1km x 1km and NO2 at a resolution of 100m x 100m.
The association between ambient air pollution and natural cause and cause-specific mortality will be assessed using Cox proportional hazard models, adjusting for major individual-level confounders. This will produce the first large-scale, multi-center study of the mortality effects of long-term air pollution exposure across Asia.