An eight-year study , from 2008-2015, conducted by IIT-Roorkee, University of Minnesota, US, and University of Surrey , UK, has shown that emissions from vehicles in Delhi have increased up to three times between 1991 and 2011; these could rise by up to 19 times by 2020.
Researchers said the study has now been accepted for publication by the international science journal “ Atmospheric Environment“.
Private vehicles’ (two-wheelers and cars) emissions–carbon dioxide, hydro carbons, PM10 (particulate matter), carbon monoxide, nitrogen oxide and toxic substances like butadiene, acetaldehyde, benzene, formaldehyde, total aldehyde, and total poly aromatic hydrocarbons have increased by 2-13 times in 2011 and 2-16 times in 2015 over 1991 levels, the researchers have found.
Two-wheelers were found, at present, to be the dominant source of emissions of what are termed Mobile Source Air Toxics (MSATs)–formaldehyde (37%), hydrocarbons (35%) and acetaldehyde (64%). Private cars were found to be responsible for the majority of the carbon monoxide (34%), benzene (48%), and total aldehyde (40%) emission. Heavy-duty commercial vehicles (HCVs) were found to have emitted nearly 46% of all particulate pollutants in 2015. Diesel cars were responsible for 10% of such pollution in Delhi.
The study attempted to record variations in various vehicular pollutants over 20 years, and offered projections for the future.
Nagpure told TOI that pollution levels in Delhi had already reached dangerous levels. If action was not taken immediately, it would become render ir reversible damage, he warned.
Researchers developed their own model, the Vehicular Air Pollution Inventory (VAPI), for measuring time-series emission analysis (1991-2011) of on-road vehicles. The research included pollution caused by non-exhaust sources like worn-out brake, poor roads or tyres and road dust. PM10 (particulate matter) emissions from tailpipe and non-exhaust sources contribute 16% of the total pollution; road dust is the big chunk of PM10 emissions, at 77% and brake wear (6%) in 2015. The study anticipates that the share of road dust in PM10 pollution would be 79% in 2020.
Nagpure said according to United Nations Environment Programme (UNEP) and World Health Organization, Delhi is the second-most populous city in the world after Tokyo, and the most polluted in the world. Air-pollution deaths have gone up two-fold between 1991and 2010 in Delhi.
MSATs can cause a wide range of serious health effects from birth defects, cancer, damage to kidneys, lungs and nervous system. Estimates from the US Environmental Protection Agency show that on-road vehicles are responsible for about half of all cancers attributed to outdoor air pollution.
Nagpure said that although action is being taken by governments to reduce pollution, much of this is focused on exhaust emissions. But no action is taken to reduce non-exhaust emissions like brake wear, road wear, tire wear and road dust.
The study projected greater pollution from buses. Cars (30-34%) were found to be producing the highest CO2 emissions during 2011 to 2015; there is likelihood that buses could dominate in the years after 2015, the researchers said.
Mono-nitrogen oxide emission has also grown significantly , with an annual rate of growth of 14%.
Two-wheelers played a dominant role in hydrocarbon emissions from 2011; buses are expected to be the biggest source of this pollutant from 2018 onwards.
Source: Times of India 19 Dec’2015