India today is the world’s fourth most significant greenhouse gas (GHG) emitter – contributing 7.08 per cent of all global emissions1. It ranks third amongst countries with the world’s worst air quality2, and 13 of its North Indian cities are among 15 of the world’s most polluted3. Transportation plays a villainous role here. Globally, it contributes nearly 305.3 MtCO2e – 0.64 per cent of all GHG emissions4, while in India, this sector is the fastest-growing source of carbon emissions5. As policymakers set the stage for adopting electric vehicles (EV) in India, we present a two-part series looking into vehicular emissions and the norms regulating them in India.
Vehicular emissions can be categorised according to whether they are direct ‘tailpipe’ emissions – formed by fuel combustion in conventional vehicles or whether they are indirect by-products of gaseous reactions in the atmosphere. We list down both kinds, below:
Carbon dioxide (CO2) is one of the primary constituents of a vehicle’s tailpipe emissions. An end product of any fuel combustion process, today, motor vehicles are estimated to contribute nearly 24 per cent of the world’s direct CO2 emissions6. While these may not pose any immediate health hazards, their increasing build-up catalyses global warming, furthering climate change.
Carbon monoxide (CO) is a highly toxic, colourless, odourless gas that arises from the incomplete combustion of fossil fuels. This is highly detrimental to health as it affects the body’s ability to absorb oxygen. Studies have found that in highly polluted cities like New Delhi, vehicular emissions are the primary source of CO, which most notably fell by nearly 86 per cent during the Covid-19 lockdown due to restrictions on vehicular movement7.
Nitrous oxide (NOx) arises from the high-temperature combustion of fossil fuels and further contributes to ozone generation. Indian cities like New Delhi, Bangalore, Mumbai, and Kolkata have some of the highest sources of NOx in the country – linked exclusively to vehicular pollution8. An excess amount of NOx gives rise to ground-level ozone. Although not directly emitted from transport, this deadly secondary gas is highly correlated with respiratory diseases and asthma upon creation.
Particulate matter (PM) are combinations of solid and liquid pollutants such as dust, soot, smoke that are easily inhalable. These are categorised as PM 2.5 or PM 10, depending on their diameter. These could be directly formed as a result of fuel combustion or could be an indirect consequence of complex atmospheric reactions. The transport sector contributes to a third of India’s PM pollution and 20-35 per cent of PM 2.5 pollution in urban Indian cities9.
Read Part 2: Vehicle Emission Norms In India