Pollution characteristics and health risk assessment of fine particulate matter and its metal elements during Chinese New Year

The Chinese Lunar New Year is a significant festival in China that leads to indoor and outdoor air pollution with distinct characteristics compared to normal times. In this study, indoor and outdoor air samples were collected and analysed to investigate the indoor and outdoor pollution of PM2.5 and its metal elements during the Chinese New Year. The findings reveal that there is a notable positive correlation between indoor and outdoor PM2.5 concentrations during the Chinese New Year, with outdoor concentrations being higher on average. The levels of PM2.5 concentrations indoors and outdoors started to increase on Chinese New Year’s Eve and peaked after the early hours of the Chinese New Year. The total concentrations of six metal elements (Cd, Cr, Ni, Cu, Pb and Zn) in indoor and outdoor PM2.5 during the Chinese New Year in 2022 were 738.73 ± 134.93 mg/kg and 1124.38 ± 553.14 mg/kg, respectively. Principal component analysis suggests that the main sources of indoor metal elements were from outdoor combustion sources and human activities, while outdoor sources were fireworks displays and emissions from coal combustion. Based on the U.S. EPA risk assessment carried out, both indoor and outdoor PM2.5 metal elements could pose a carcinogenic risk to adults.