Sources and exposure risk of trace elements for traffic policemen in roadside locations

Abstract

Samples of PM2.5 and PM10 at four types of roadside location (major road, secondary road, branch road, and expressway) in Tianjin were collected and analyzed in 2015. The average annual roadside PM2.5 and PM10 concentrations were higher than the national ambient air quality standard (NAAQS: GB3095-2012). The chromium (Cr), manganese (Mn), nickel (Ni), zinc (Zn), arsenic (As), and cadmium (Cd) concentrations in both PM2.5 and PM10 over four seasons displayed significant differences (p < 0.05). An enrichment factor (EF) analysis revealed that Cd, copper (Cu), Zn, As, Ni, and Pb in PM2.5 and PM10 mainly originated from anthropogenic sources. A factor analysis (FA) and correlation analysis (CA) revealed that vehicle emissions (exhaust and non-exhaust), soil dust, coal combustion, and industrial emissions were the main sources of roadside PM2.5 and PM10 in Tianjin. Both the total hazard quotients (total HQ) and the total carcinogenic risk (total CR) for selected elements in PM2.5 and PM10 were within acceptable limits. The HQ of Pb was higher than for other metals, and it should therefore be given special attention. The CR for traffic policemen was highest for Cr exposure (1.01 × 10−5 for PM2.5 and 1.52 × 10−5 for PM10), followed by As and Ni. A sensitivity analysis showed that the total contributions of the metal concentrations, exposure time (ET), and exposure frequency (EF) accounted for over 50% of the risk for Cr, As, and Ni, suggesting that these metals had the greatest impact on the uncertainty of health risk assessments.