Calcutta, June 7 :    Calcutta, June 7:  Automobile-makers and oil companies are ready to switch over to liquefied petroleum gas (LPG) once the fiscal incentives for the conversion are announced. Owners of old cars will be required to shift to LPG by the year-end, in a bid to reduce air pollution. At a Society of Indian Automobile Manufacturers workshop on LPG infrastructure and future plans at the state pollution control board office on Thursday, experts discussed conversion and retrofitting of old cars. With most of the technical expertise in place, car manufacturers and oil companies said they were waiting for the government to announce the fiscal incentives. Pollution board officials pointed out that 90 per cent of the old taxis and buses emitted noxious smoke. These vehicles accounted for half of the air pollution in the city, they said. S.A. Nafis of Hindustan Motors said the company would be ready to offer the LPG option to the customers by September. It was on the threshold of launching upgraded diesel engines, he said. E.A. Vimal Nathan of Bharat Petroleum pointed out that the success of LPG-driven cars would depend on pricing incentives, a sound dispensing network and monitoring. He said the dispensing centre, which had been set up in Delhi after the Union government cleared the use of LPG in cars, could be replicated in Calcutta. Spelling out the safety aspects of LPG storage and dispensation, G.L. Deb, deputy chief controller of explosives in Calcutta, said LPG cylinders scored over CNG ones in that they were lighter and cheaper. Retro-fitting of cars should be done only in authorised garages, he said. Environment minister Manab Mukherjee said more such workshops were in the offing to facilitate the transition to LPG.