Abstract
Most prospective studies on the health effects of particulate ambient air pollution exposure have focused on high-income countries, which have much lower pollutant concentrations than low-income and middle-income countries (LMICs) and different sources of pollution. We aimed to investigate the cardiorespiratory health effects of particulate ambient air pollution exposure in LMICs exclusively. For this systematic review and meta-analysis, we searched PubMed, Web of Science, Embase, LILACS, Global Health, and Proquest for studies published between database inception and Nov 28, 2016, investigating the cardiorespiratory health effects of particulate ambient air pollution exposure in LMICs. Data were extracted from published studies by one author, and then checked and verified by all authors independently. We pooled estimates by pollutant type (particulate matter with a diameter of <2·5 μm [PM2·5] or 2·5-10 μm [PM10]), lag, and outcome, and presented them as excess relative risk per 10 μg/m3 increase in particulate ambient air pollution. We used a random-effects model to derive overall excess risk. The study protocol is registered with PROSPERO, number CRD42016051733. Of 1553 studies identified, 91 met the full eligibility criteria. Only four long-term exposure studies from China were identified and not included in the meta-analysis. A 10 μg/m3 increase in same-day PM2·5 was associated with a 0·47% (95% CI 0·34-0·61) increase in cardiovascular mortality and a 0·57% (0·28-0·86) increase in respiratory mortality. A 10 μg/m3 increase in same-day PM10 was associated with a 0·27% (0·11-0·44) increase in cardiovascular mortality and a 0·56% (0·24-0·87) increase in respiratory mortality. Short-term exposure to particulate ambient air pollution is associated with increases in cardiorespiratory morbidity and mortality in LMIC's, with apparent regional-specific variations. None.
Highlights
Ambient air pollution is one of the biggest environmental threats to human health and is estimated to contribute to 2·9 million annual deaths globally,[1] of which more than 85% occur in low-income and middle-income countries (LMICs).[2]
To accurately quantify the health burden of Particulate matter (PM), researchers urgently need to obtain an exposure–response function that is specific to LMICs, which would minimise the spatial uncertainty introduced by extrapolation of results from high-income countries
In LMIC regions exclusively, we found particulate ambient air pollution to be associated with both cardiorespiratory mortality and morbidity, with more consistent estimates found for mortality
Summary
Ambient air pollution is one of the biggest environmental threats to human health and is estimated to contribute to 2·9 million annual deaths globally,[1] of which more than 85% occur in low-income and middle-income countries (LMICs).[2]. High concentrations of PM have been reported from metropolitan areas around the world, LMICs, because of recent sharp economic growth.[9] research on the health effects of PM is unreflective of PM’s growing ubiquity across the world, with most studies, multicity studies, mainly done in North America[10,11] and western Europe,[5,12,13] despite populations in LMICs having the greater burden of PM. To accurately quantify the health burden of PM, researchers urgently need to obtain an exposure–response function that is specific to LMICs, which would minimise the spatial uncertainty introduced by extrapolation of results from high-income countries.
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