Spatiotemporal patterns of particulate matter (PM) and associations between PM and mortality in Shenzhen, China

BACKGROUND: Most studies on air pollution exposure and its associations with human health in China have focused on the heavily polluted industrial areas and/or mega-cities, and studies on cities with comparatively low air pollutant concentrations are still rare. Only a few studies have attempted to analyse particulate matter (PM) for the vibrant economic centre Shenzhen in the Pearl River Delta. So far no systematic investigation of PM spatiotemporal patterns in Shenzhen has been undertaken and the understanding of pollution exposure in urban agglomerations with comparatively low pollution is still limited. METHODS: We analyze daily and hourly particulate matter concentrations and all-cause mortality during 2013 in Shenzhen, China. Temporal patterns of PM (PM(2.5) and PM(10)) with aerodynamic diameters of 2.5 (10) μm or less (or less (including particles with a diameter that equals to 2.5 (10) μm) are studied, along with the ratio of PM(2.5) to PM(10). Spatial distributions of PM(10) and PM(2.5) are addressed and associations of PM(10) or PM(2.5) and all-cause mortality are analyzed. RESULTS: Annual average PM(10) and PM(2.5) concentrations were 61.3 and 39.6 μg/m(3) in 2013. PM(2.5) failed to meet the Class 2 annual limit of the National Ambient Air Quality Standard. PM(2.5) was the primary air pollutant, with 8.8 % of days having heavy PM(2.5) pollution. The daily PM(2.5)/PM(10) ratios were high. Hourly PM(2.5) concentrations in the tourist area were lower than downtown throughout the day. PM(10) and PM(2.5) concentrations were higher in western parts of Shenzhen than in eastern parts. Excess risks in the number of all-cause mortality with a 10 μg/m(3) increase of PM were 0.61 % (95 % confidence interval [CI]: 0.50–0.72) for PM(10), and 0.69 % (95 % CI: 0.55–0.83) for PM(2.5), respectively. The greatest ERs of PM(10) and PM(2.5) were in 2-day cumulative measures for the all-cause mortality, 2-day lag for females and the young (0–65 years), and L02 for males and the elder (>65 years). PM(2.5) had higher risks on all-cause mortality than PM(10). Effects of high PM pollution on mortality were stronger in the elder and male. CONCLUSIONS: Our findings provide additional relevant information on air quality monitoring and associations of PM and human health, valuable data for further scientific research in Shenzhen and for the on-going discourse on improving environmental policies.