As Delhi heads for another polluted winter, state Environment Minister Gopal Rai on Monday said that the "odd-even" scheme will be the government's last resort if other methods to improve the air quality fail."The odd-even scheme would be our last resort. If rest of the methods to curb the air pollution fails, we will think about its implementation this year," Rai said at a press conference.The odd-even scheme is a traffic rationing measure under which private vehicles with registration numbers ending with an odd digit are allowed on roads on odd dates and those with an even digit on even dates. Last year, it was put into force from November 4 to 15.Meanwhile, the capital city's air quality index stood at 243 in the afternoon, which falls in the 'poor' category. The air pollution reaches its peak every winter, when pollution from stubble burning combines with the suspended water droplets in the lower atmosphere to form a thick blanket of noxious smog.In a bid to control the pollution, Delhi Chief Minister Arvind Kejriwal had recently launched a new anti- pollution campaign -- 'Red Light On, Gaadi Off' - starting from October 21, under which motorists will be encouraged to switch off vehicles while waiting for the lights to turn green at traffic signals.Rai also said that the city government will deploy 2,500 environment marshals across city to generate awareness about its recently-launched campaign, which, he claimed, will bring down the pollution caused due to vehicular emission by 15-20 per cent."The marshals will hold placards in a bid to aware people. In the first three days, they will also hand out roses to people who do not switch off the engines with 'Gandhigiri'," he added.The Delhi Traffic Police has given information to the government about the 100 busiest intersections of Delhi, where these environmental marshals will be deployed in two shifts. The police has also identified ten large intersections, like ITO, where more such volunteers will be positioned.