Today on Diwali, if you are in Delhi, you will have to celebrate the festival without firecrackers. Supreme Court of India decided to curb the effect of Diwali firecrackers on air pollution by banning their sale in Delhi. But are firecrackers the only reason which makes Delhi’s air so foul? There are varied conclusions drawn by various research and studies done in the recent past. One of the most important studies was published in the year 2003 by Ministry of Environment and Forests. The research was based on data collected from 1970-71 to 2000-01 and it said that in 30 years, vehicles’ contribution to particulate matter in Delhi’s air increased over three times (23 percent to 72 percent). However, several studies done after that year, differ on their assessments of the role played by vehicles in contributing to air pollution in the national capital, according to an Indian Express report.
According to the IE report, in 2007, three years before the Commonwealth Games, the state government was worried about the rise in a number of vehicles in the city. That year, Department of Environment and the Government of the NCT of Delhi sponsored a study that done by IIT Delhi. The study revealed that vehicles in the city increased dramatically from 2.3 million in 1975 to 4.2 million in 2004. It had estimated that the number will go upto 7.2 million in 2016. The study concluded that “control on emissions of pollutants from vehicular traffic necessitates the control on the new registration of commercial diesel vehicles in Delhi”. It noted that the “emission of air pollutants [is] directly proportional to the number of vehicles and concentration of ambient air pollutants is also directly proportional to the emission of air polluting sources”.
Furthermore, there was another study done in 2008 by Central Pollution Control Board (CPCB) with National Environmental Engineering Research Institute (NEERI). The study found that road dust was the largest contributor (52.5 percent) to particulate matter in the city’s air. This was followed by industries (22.1 percent). Interestingly, the study attributed only 6.6 percent of particulate emissions to vehicles.
Again in 2011, a project named Safar (System of Air Quality Forecasting and Research) was published in ‘Atmospheric Environment’. The project was developed for air quality forecasting during the Commonwealth Games. The study done under the project found that road dust from paved and unpaved roads was the largest contributor to air pollution (55 percent), followed by residential sources (15 percent), transport and vehicular pollution (13 percent), industrial sources (12 percent), and power (5 percent).
Last year in January a “Comprehensive Study on Air Pollution and Green House Gases” was published by IIT Kanpur. The study focused on five components: air quality measurements, emission inventory, air quality modelling, control options and an action plan. The study, while underlining the role of road dust, also stressed on vehicular emissions. It said that moving vehicles contributed to over 50 percent of Delhi’s air pollution, and road dust (38 percent), vehicular pollution (20 percent), domestic sources (12 percent), industrial sources (11 percent) came in later.