Particulate matter pollution in the megacities of the Pearl River Delta, China - a systematic literature review and health risk assessment.

The exposure to ambient particulate matter (PM) pollution is a major threat to public health. Chinese megacities are coined by high levels of PM. Our aims were to examine the concentration levels of PM in megacities (Guangzhou, Hong Kong, and Shenzhen) of the Pearl River Delta (PRD), South China; to compare the results with international and national air quality guidelines; and to assess the health impact in terms of possible reductions in premature deaths due to PM reduction. The Medline(®) data base was used to identify published studies (systematic literature search). Based on our appraisal criteria 13 studies remained in the analysis. Additionally, publicly available data were extracted from data sources provided by municipal authorities of the cities under study. PM data reported in μg/m(3) were abstracted from single studies and municipal reports. If possible, the PM data were stratified for season of data collection (summer/winter half-year) and simple means were calculated for cities, seasons and months. Based on the abstracted data, a health impact assessment (HIA) was done in order to estimate potential preventable premature deaths due to PM pollution in the cities. Almost all PM data exceeded national and international air quality guidelines. Our HIA showed that in Guangzhou ten thousands of premature deaths could be prevented if the PM burden was reduced to these air quality limit values. We identified no suitable epidemiological study reporting PM according to our study protocol. Further epidemiological studies should be carried out to more precisely determine the spatial distribution of PM-related health risks in PRD. Environmental protection measures and public health interventions are required to reduce burden of PM-related diseases in PRD.