Delhi cannot blame its polluted air on its neighbours this Diwali. A forecast released by the Union ministry of earth sciences on Monday stated that the air quality in Delhi this year will be directly proportional to firecrackers burst and vehicular emissions within city limits.This would be different from the last few years, when post-Diwali pollution was mostly blamed on stubble-burning in Punjab and Haryana. The report said prevalent weather conditions will not allow polluted air from neighbouring states to reach Delhi until at least October 21. Emissions triggered within city limits will not disperse easily either.The forecast by the ministry’s System of Air Quality and Weather Forecasting and Research (SAFAR) takes three scenarios into account. If the city bursts the same amount of firecrackers as last year, the pollution level would be higher than 2014 and 2015 but less than 2016. If the number of crackers sees a 50% reduction, the pollution would be less than 2014 but greater than 2015. If no firecrackers are burst, Delhi would have the cleanest Diwali since 2013. Last year’s festive season triggered the worst smog in 17 years, forcing the Delhi government to shut down schools and construction sites. Delhi University, Noida, Dheerpur and Mathura Road areas in the city may witness the most pollution this year, while Aya Nagar, Lodhi Road, Pusa and Palam could be left relatively unscathed.Forced to take reparative measures, the Supreme Court has banned the sale of fire crackers in the national capital region until the start of November. The move drew a mixed response from city residents. “The upper air winds responsible for transporting pollutants from distant sources, such as places where crop stubble is being burnt, are not strong enough this time. They are unlikely to impact Delhi,” the forecast said.<img src=”http://www.hindustantimes.com/static/ht2017/10/1710pg1a.jpg” width=”100%”/>There, however, is a downside to this phenomenon. “As the surface winds are calm, they are unlikely to blow the local pollution away. Therefore, the pollutants may remain trapped in Delhi’s air for a longer period,” the forecast added.Meanwhile, environmentalists have asked city residents to say no to crackers and go easy on motorised vehicles. “The new forecast shows that if Delhi wants to prevent a repeat of last year’s smog situation, a lot will depend on the extent of firecrackers burnt here. Also, one shouldn’t forget the Diwali traffic’s contribution to pollution levels,” said Anumita Roychowdhury, head of the air pollution division at the Centre for Science and Environment.Delhi experiences some of its worst traffic jams in the days leading up to Diwali. The situation turns especially bad during Dhanteras, which falls on Monday.“Vehicles are one of the biggest contributors to pollution in the city, and it increases from 20-28% during the winter. Pollutants don’t get dispersed fast enough during this time of the year, aggravating the situation,” said D Saha, head of the air quality laboratory at the Central Pollution Control Board.“The humidity in Delhi is increasing, and the temperature is dropping. This may increase the holding capacity of emissions from the firecrackers. An anti-cyclonic circulation may lead to the slowing down of surface winds, which would then cause the local pollution to stagnate,” SAFAR predicted.