Elemental Composition and Health Risk Assessment of PM10 and PM2.5 in the Roadside Microenvironment in Tianjin, China

To determine the elemental composition and health risk of particles in the roadside microenvironment, particulate matter samples (PM10 and PM2.5) were collected at the side of four roads in winter, spring, and summer of 2015. The total concentrations of crustal and trace elements and the average concentrations of most single elements followed the sequence of spring, winter, and summer. Crustal elements accounted for 18.9%, 13.2%, and 9.3% of the PM10 and 15.1%, 11.2%, and 18.8% of the PM2.5 in the three seasons, respectively. On average, Zn contributed the largest share, accounting for 34.0%, 32.2%, and 34.2% of the total trace elements in PM10 and for 35.2%, 28.3%, and 35.6% in the PM2.5 for winter, spring, and summer, respectively. The enrichment factor results showed that Mn, K, Na, Co, and Si originated in crustal sources; V, Ca, Mg, Mo, Cr, Fe, Ti, and Ba were derived from both anthropogenic and crustal sources; and Cd, Sb, Zn, Cu, Pb, As, and Ni were largely derived from anthropogenic sources. The results of principal component analysis explained 72.64% of the total variance for PM10 and 78.76% of the variance for PM2.5. Possible sources include resuspended road dust, vehicular exhaust, fugitive dust (road dust and soil dust), and tire/brake wear. The respective ratios of Fe/Al, Mn/V, Cu/Sb, Cu/Zn, Zn/Pb, V/Ni, and Cu/Pb in this study were 0.58, 2.87, 11.07, 0.28, 1.23, 1.34, and 4.45 for PM10 and 1.07, 0.83, 23.07, 0.44, 1.83, 1.60, and 4.18 for PM2.5. Accumulative non-cancerous toxic elements in winter and spring may pose risks to roadside workers via inhalation. The integrated cancer risks (CR) of As, Co, Cd, Cr, Ni, and Pb in PM2.5 and PM10 ranged from 1.58E-05 to 4.95E-05 CR.