Quantification of Heavy Metals in Indoor Dust for Health Risk Assessment in Macao

The presence of heavy metals plays a significant role in indoor air quality, which poses a serious public health problem since most of the population spends over 90% of their time in indoor environments. This work investigates heavy metals in indoor dust across different occupational settings in Macao. Field sampling was conducted in five representative locations, which included restaurants, student dormitories, auto repair shops, offices, and parking security rooms, with a total of 11 samples collected in this study. Dust in the form of particulate matter was collected from air conditioning filters to quantify 14 heavy metal contents. The PMF model was applied for source apportionments of the heavy metals, while a health exposure model was used to assess health risks and evaluate the non-carcinogenic and carcinogenic risks in the five representative workplaces. The PMF model identified six major pollution sources: traffic emissions (23.800%), building materials (21.600%), cooking activities (18.500%), chemicals (15.200%), electronic devices (12.300%), and outdoor seaport activities (8.600%). The health risk assessment showed that the overall non-carcinogenic risk (HI = 6.160 × 10−6 for inhalation, 1.720 × 10−3 for oral ingestion, and 2.270 × 10−5 for dermal contact) and total HI (1.749 × 10−3) and carcinogenic risk (6.570 × 10−9) were below the safety threshold, showing minimal health risk problems. Nevertheless, nickel and chromium were identified as the main contributors to potential long-term risks.