Re ECF Project: 2010-35

Project Title: Evaluating the health effects of distinct PM2.5 components for more targeted air quality control measures in Hong Kong

Applicant: Dr. Linwei TIAN of The Chinese University of Hong Kong

Total Approved Grant: $284,050

Duration: 1/7/2011 to 30/9/2012

Project Status/Remarks: Completed

The project aims to estimate the association between the distinct PM2.5 chemical components and cardiovascular mortality in Hong Kong by using time-series approaches.

Summary of the Findings/Outcomes:
From the dozens of PM components, the project team chose 8 chemical components for the health effects analysis based on source types identified in previous studies. These 8 components represent the major emission sources in Hong Kong: elemental carbon for vehicle exhaust, nickel for residual oil combustion, chlorine ion for fresh sea salt, sodium ion for aged sea salt, aluminium for crustal soil and dust, sulfate for secondary sulfate, nitrate for secondary nitrate, and potassium ion for biomass burning.

Among the 8 components, nickel was the only component that showed statistically significant association consistently with both cardiovascular and respiratory mortality, based on either PM2.5 data or PM10 data in TW station. After the adjustment for other components, an interquartile increase of PM2.5 nickel concentration of the current day was associated with 3.2 % (95% CI, 1.4 to 6.3) increase in the 3-day moving total of cardiovascular mortality and 3.8% (95% CI, 1.3 to 5.1) increase in that of respiratory mortality. The ER estimates for nickel based on HT station data were approximately 60% smaller.

The excess risks of cardiovascular and respiratory mortality associated with nickel point to the particular importance of controlling emissions from residual oil combustion.