The Buddhadeb Bhattacharjee government has decided to slap a spot fine of Rs 50 on users of banned plastic bags. Shopkeepers handing out the bags will have to shell out Rs 500, according to a notification issued earlier this month. Officials feel the pollution cost, to be collected by the civic and other local authorities, will act as a deterrent against the use of banned plastic bags. "It is like a compulsive awareness strategy. We think a few exemplary fines will result in a significant reduction in the use of banned plastic bags,' said environment secretary M.L. Meena. Plastic bags less than 40 micron thick and smaller than 16inchesx12inches are banned in the state since June 2007. But even environment department officials admit that the ban is rampantly flouted. "Slapping fines on users can be an effective tool. In legal parlance, this is called preventive theory of punishment and it works,' said advocate Gitanath Ganguly. According to him, a spot fine on pedestrians walking down the Sealdah flyover, introduced in the early 1980s, still remains an effective deterrent. The environment department feels the penalty on the users and providers of plastic bags will yield a similar result. "The proceeds will be spent on environment upgrade measures,' said an official of the department. The directive is based on a letter from the Union urban development ministry to the chief secretaries of all states. The letter described how a similar measure in Garhwal, in Uttarakhand, brought down the use of plastic bags. A section of green activists, however, is sceptical whether the plastic penalty will be enforced. "The environment department keeps issuing directives that never get implemented,' said Subhas Dutta.