Sources and health risk of organic compounds in respirable particles in Tehran, Iran

Abstract

Forty-one respirable particle (PM4) samples were collected from October 2011 through March 2012. This timespan covered the fall and winter seasons in Tehran, Iran. The associated polycyclic aromatic hydrocarbon (PAH) and n-alkane concentrations were analyzed to investigate the sources of these compounds and health risks of the former. The average total PAH and n-alkane concentrations were 16.2 ng/m3 and 758 ng/m3, respectively. The most abundant PAHs were 2- and 3-ring compounds, while the most abundant n-alkanes were nC16 and nC18. The results of source identification by factor analysis (FA) are consistent with and complementary to those from diagnostic ratios (DRs). The PAH DRs indicate a dominant contribution from pyrogenic sources, in particular diesel engines from local traffic sources, while FA reveals a diesel-fuelled vehicle emission related factor, a gasoline engine emission-related factor, an industrial source factor and a wood combustion, incineration and tire tread source factor. The n-alkane DRs indicate dominant contributions from anthropogenic sources or vehicular emissions, while FA reveals a fossil fuel combustion factor and a biogenic source factor. Although the average BaP concentration was below the Iran Department of Environment's annual average standard of 1 ng/m3, the BaP-equivalent concentration of the PAHs (BaPPEQ) indicates harmful effects cannot be ruled out. The ICRL and ICRU data suggests a potential cancer risk incidence of about 1-54 individuals per million in the population from a lifetime of 70 years inhalation of particle associated PAHs in Tehran. These findings highlight the importance of reducing emissions from traffic, in particular emissions from diesel-fuelled vehicles, in Tehran.