Polycyclic aromatic hydrocarbons in air and their toxic potency

Conclusions In spite of very high toxic potency of PAH, in India environmental monitoring and assessment of PAH is rarely done compared to European countries and US. The Central Pollution Control Board (CPCB) had recently initiated regular monitoring of PAHs in ambient air in select cities. According to CPCB, ambient air PAH in Delhi ranged between 9.4–60.9 nanograms per cubic meter (ng/m³) during 1999–2000 with higher values recorded in winter. Other research studies reported about 4.999.56 ng/m³ of benzoa]pyrene in suspended paniculate matter (SPM) during 1986 in urban Delhi. In Calcutta, sum of 12 PAHs was 22.91 and 190.96 ng/m³ in SPM at Jadavpur and Maulali respectively, in 1994. The average benzoa]pyrene concentration was 10.4+4.76 ng/m³. These levels are apparently manifold higher than the European standards. Apart from few such studies no detailed studies are available in India. Even in the current standards and specifications for diesel engines there is no emission limit for PAH. Recently it had specified that 10% of PAH by hydrocarbons as limit that should be adopted by 2005. In the current Indian scenario, especially after the economic liberalization in 1991, the motor vehicle population is increasing rapidly, leading to corresponding increase in PAH emissions. The role of PAHs in cardiovascular mortality, cancer cases and several other health abnormalities that are reported nowadays cannot be ignored.