Characterization, sources, and health implication of organophosphate flame retardants in PM2.5 in Hong Kong

Organophosphate flame retardants (OPFRs) are emerging organic pollutants that have been found ubiquitously in the atmospheric fine particulates (PM2.5). Given their potential carcinogenic and neurotoxic effects, exposure to OPFRs via PM2.5 inhalations may lead to adverse health effects on humans. However, until now, information on their sources, occurrence, and transformation in the atmosphere and the human health risks upon exposure to PM2.5-bound OPFRs is still limited. In this study, we propose to develop a novel and sensitive analytical technique to characterize the PM2.5-bound OPFRs in Hong Kong by using atmospheric pressure gas chromatography-tandem mass spectrometry (APGC-MS/MS). PM2.5 samples regularly collected in Hong Kong SAR during a 1-yr period will be analyzed, and the ambient concentrations and seasonal variations of PM2.5- bound OPFRs will be determined. Besides OPFRs, the major aerosol constitutes and chemical markers of various PM2.5 sources will be measured, especially those from anthropogenic sources, including vehicle exhaust, e-waste recycling, industry, marine vessels, and biomass burning. We will then apply positive matrix factorization to identify the major emission sources of OPFRs and quantitatively estimate the individual source contributions to OPFRs in Hong Kong. The influence of different environmental parameters, such as air mass origins and temperature, on the contamination profiles of and relative source contributions to PM2.5-bound OPFRs, will be investigated. Preliminary health risk assessment of human exposure to PM2.5-bound OPFRs in the region will be evaluated using the estimated daily intakes of different age groups of people. This project will be the first comprehensive study on the characterization and source apportionment of PM2.5-bound OPFRs in Hong Kong. The outcome of this study will expand the scientific database of the speciation, levels, and sources of ambient OPFRs and provide useful information for more precise and targeted emission controls of OPFRs in the atmosphere, which may help better protection of public health from PM2.5 pollution.