"If the current trends of vehicle population, fuel and emission standards persist, PM 2.5 (PM particles smaller than 2.5 micrometres) emissions will increase by a factor of three, and those of NOx (one of a group of highly reactive gasses) will increase by a factor of five," according to the report.
The report was prepared by The Energy and Resources Institute (TERI), University of California, San Diego (UCSD) and the California Air Resources Board (CARB).
According to the report, titled 'Options to Reduce Road Transport Pollution in India',the transport sector contributes about 15 to 50 per cent of PM 2.5 emissions in cities, and is a dominant contributor to NOx emissions.
The World Health Organization estimates that, of the 67 risk factors studied in its Global Burden of Disease project, outdoor air pollution was ranked 5th in mortality and 7th in health burden in India, contributing to over 6,27,000 deaths and 17.7 million healthy years of life lost in 2010.
The report establishes the scientific basis for reducing emissions, the technologies available, and governance issues that need to be urgently addressed to improve air quality.
The report comes at a time when the transport sector is experiencing significant growth in the country and vehicle population has grown seven-fold in the past two decades. It also presented city-wise contribution in emissions from the transportation sector.
Within the transportation sector, heavy-duty trucks are the largest black carbon (BC) emitters followed by bus, which is followed by three-wheelers. As for PM 2.5, heavy-duty trucks emit most followed by two-wheelers and then three-wheelers.
"City wise, transportation also stands as the largest emitter of PM2.5 in Bangalore (followed by Diesel Generator sets), Pune (followed by secondary formation) and Kanpur (followed by domestic)," it says.
The report says that drastic reduction (more than 90 per cent) of Particulate Matter (PM) and Nitrogen Oxides (NOx) from the transportation sector, primarily diesel vehicles and buses, will have the largest and most immediate beneficial impact on human health and food supply.
"More than 75 per cent of PM 2.5 particles (also known as aerosols in the climate literature) from diesel vehicles is black carbon aerosols (or particles), a major contributor to global warming and melting of Himalayan glaciers," says the report.
It is expected to grow from 140 million in 2011 to about 400 million during the next two decades. "Clearly, Indian citizens are on the move and are prospering from the growth," it said.
"But this growth will worsen the air pollution problem in India and will come at a huge cost to public health and crop yields. It also has consequences to monsoon rainfall, Himalayan glaciers and regional climate," it says.
PM 2.5 is the dominant contributor to premature deaths and numerous other illnesses, followed by Ozone and NOx, the other two major contributors to health impacts.
It says that drastic reductions in PM 2.5 and NOx emissions will also mitigate impacts of black carbon and nitrate aerosols (resulting from NOx) on precipitation and regional climate change. "It is a win-win action for all aspects of sustainability," it added.