A novel approach for assessing the spatiotemporal trend of health risk from ambient particulate matter components: Case of Hong Kong.

The spatiotemporal assessment of health risk due to exposure to particulate matter (PM) components should be well studied because of the different toxicity among PM components. However, this research topic has long been overlooked. This study aimed to examine the spatiotemporal variability in ambient respirable PM (PM) components associated inhalation carcinogenic and non-carcinogenic risk (ICR and INCR) in Hong Kong over 2015-2019. The land-use regression (LUR) approach was adopted to predict the spatial distribution of PM component concentrations for the period of 2015-2019, whereas the ICR and INCR values of PM components were also estimated using the classic health risk assessment method. Both concentration of PM and INCR of PM components showed a general decreasing trend, while ICR of PM components increased slightly over the study period. LUR-model-based spatial maps at 500 m × 500 m resolution revealed the important spatial variability in PM and its eleven components, and their associated ICR and INCR values. High pollution levels and high ICR and INCR of studied PM components were generally found in developed urban areas and along the road network. Despite the fact that the PM concentrations met the Hong Kong annual PM air quality objective of 50 μg/m, there was still significant potential health risk from the studied PM components. This study highlights the importance of taking PM component concentrations and associated inhalation health risk as well as PM mass concentrations into account for the perspective of air quality management and protecting public health.