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• Characteristics, sources and health risks of PM 2.5 -bound elements were explored. • The accumulated cancer risk exceeded the threshold of 10−6. • Dust was the leading source, but traffic source was the main contributor of risks. • Serious health risks caused by trace elements existed in special events. To gain a comprehensive understanding of sources and health risks of trace elements in an area of China with high population densities and low PM 2.5 concentrations, 15 trace elements (Al, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, As, Sn, Ba, Pb) in PM 2.5 were monitored from December 2020 to November 2021 in a representative city, Xiamen. The concentrations of trace elements in Xiamen displayed an obvious seasonal variation and were dominated by K, Fe, Al, Ca and Zn. Based on Positive Matrix Factorization analysis, source appointment revealed that the major sources of trace elements in Xiamen were traffic, dust, biomass and firework combustion, industrial manufacture and shipping emission. According to health risk assessment combined with the source appointment results, it indicated that the average noncarcinogenic risk was below the threshold and cancer risk of four hazardous metals (Cr, Ni, As, Pb) exceeded the threshold (10−6). Traffic-related source had almost half amount of contribution to the health risk induced by PM 2.5 -bound trace elements. During the dust transport period or Spring Festival period, the health risks exceeded an acceptable threshold even an order of magnitude higher, suggesting that the serious health risks still existed in low PM 2.5 environment at certain times. Health risk assessment reminded that the health risk reduction in PM 2.5 at southeastern China should prioritize traffic-related hazardous trace elements and highlighted the importance of controlling vehicles emissions in the future. [ABSTRACT FROM AUTHOR]