The union Ministry of Environment and Forests had published a white paper in 2003.
It reported that in the time between 1970 & 2000, the contribution of vehicles to particulate matter in Delhi’s air rose from 23% to 72%.
The four major government studies carried out since then have differed on the relative contribution of sources of particulate matter in Delhi’s air.
What are the findings?
IIT-Delhi, 2007 - The study was commissioned to specifically understand the contributions of vehicle of different types to vehicular air pollution.
A key finding was that “tempos contribute maximum amount of concentration of NOx and PM (58%) followed by trucks (24.1%), buses (12%), cars/taxis (9.7%), small trucks (3.7%) and tractor, trailer (0.18%).”
It concluded that “control on emissions of pollutants from vehicular traffic necessitates the control on the new registration of commercial diesel vehicles in Delhi”.
NEERI, Nagpur 2008 - The study was commissioned after the need for “better understanding” of air pollution sources was “recognised” in the Auto-Fuel Policy Document, 2002.
The study identified road dust as the biggest contributor (52.5%) to particulate matter in Delhi’s air, followed by industries (22.1%).
It attributed only 6.6% of particulate emissions to vehicles.
For NOx, the study found industries contributed 79% and vehicles 18%.
Vehicles were the main source of CO and hydrocarbons: 59% and 50% respectively.
SAFAR, 2011 - System of Air quality Forecasting and Research (SAFAR) project was developed for air quality forecasting during the Commonwealth Games.
The study reached the “surprising” conclusion that road dust from paved and unpaved roads contributed the largest share to air pollution (55%), followed by residential sources (15%), transport and vehicular pollution (13%), industrial sources (12%), and power (5%).
Particulate pollution is a major problem for Delhi specially during winter and fire event festival and that the situation with regard to gaseous pollution (such as NOx and sulphur oxides) was “reasonably better”.
IIT-Kanpur, 2016 The study carried out sampling during the winter of 2013-14 and the summer of 2014. It had five components: air quality measurements, emission inventory, air quality modelling, control options and an action plan.
For PM2.5, the source apportionment, according to the study, was: road dust (38%), vehicular pollution (20%), domestic sources (12%), industrial sources (11%), concrete batching (6%), hotels and restaurants (3%), municipal solid waste burning (3%), diesel gensets (2%), industrial area sources (2%), and cremation, aircraft and medical incinerators (1% each).
For NOx emissions, industrial point sources (52%) and vehicles (36%) were the biggest contributors, followed by diesel gensets (6%), the study found.
