New Delhi, Oct. 28 -- The Delhi transport department issued 4,572 challans to vehicles without valid pollution under control (PUC) certificates and impounded 145 buses between October 11 and 25 as part of a crackdown on vehicular pollution, government data showed on Tuesday. During the same period, the department took action against 48 vehicles emitting visible smoke, 15 vehicles carrying building material and impounded 558 overloaded vehicles. The enforcement drive was carried out in accordance with directions issued by the Commission for Air Quality Management (CAQM), the department said. A total of 39 teams have been deployed round the clock at 13 major border points and toll plazas to check violations. The action comes amid concerns ove...