Amid rising concerns over air pollution and the major contribution of emissions from motor vehicles in urban parts of the country, a study of heavy polluter vehicles on the Mumbai-Pune expressway by researchers from the Indian Institute of Technology (IIT) Bombay suggests the need for stringent policies to restrict vehicular pollution. To conduct the study, the researchers set up their pollutant-measuring equipment at the entry and exit of the Kamshet-I tunnel located on the Mumbai-Pune expressway. According to researchers, roadway tunnels offer ideal conditions for this study because of the confined space within the tunnel, which effectively traps the emissions from the vehicles, barring the influence of other ambient sources. The study collected data for over two weeks. Along with exhaust emissions (resulting from incomplete combustion of fossil fuels), non-exhaust emissions (resulting from brake wear, tyre wear, road surface wear, and resuspension of road dust) were also collected. The traffic data was collected using high-definition video cameras. The researchers observed that the pollutant levels at the exit of the tunnel were significantly higher than those at the entry. The IIT Bombay researchers estimated that super-emitters constituted an average of 21% of the total vehicle fleet in the Kamshet-I tunnel, where 10% of the fleet had a visible plume of smoke and 11% were overloaded freight vehicles. Super-emitters are vehicles that are either old, poorly maintained, over-loaded heavy-duty vehicles or all of them. They release significantly higher amounts of pollutants compared to the other vehicles. The team developed a mathematical model to predict the share of super-emitters in any given real-world traffic in India by factoring in the shares of heavy-duty vehicles and light-duty vehicles, their respective ages, and fuel composition. “Until now, there has been no study in India that has examined the share of super-emitters in real-world vehicular fleets. The motivation was to reduce uncertainty in the emission estimation from real-world vehicular fleets,” said Sohana Debbarma, a researcher from the study held under the guidance of Prof Harish Phuleria and Prof Chandra Venkataraman, which highlights importance of enforcing strict regulations and maintenance programs on vehicle fleet with respect to super-emitters and their disproportionate release of pollutants.
