High levels of polycyclic aromatic hydrocarbons (PAHs), a group of toxic carcinogens, have been detected in the air in various parts of the city.
A study conducted in Ambattur, Kolathur, Saidapet and Egmore by the department of environmental management, Bharatidasan University, Tiruchy, showed the average concentration of particle-associated PAHs ranged from 325.7 to 790.8 nanogram/cubic metre — an alarming pollution level — in Chennai.