With stubble burning at its peak in Punjab and Haryana after the kharif season, scientists from the National Environmental Engineering Research Institute (Neeri) have started tracking pollutants from the two states. The project has been initiated to determine the impact of crop burning on Delhi's air quality.

The institute has undertaken the study for Central Pollution Control Board (CPCB) and a team from Nagpur, Delhi and Mumbai are monitoring air at different locations. "We have set up three monitoring stations in Delhi and two in Punjab and Haryana each, and are monitoring the air simultaneously since the last ten days," said Neeri director Rakesh Kumar.

The equipment have been deployed at interface of urban and rural areas to get most accurate results. "After continuing the monitoring for another week, the air samples will be collected for fingerprint analysis. Since the stubble burning particles are different from normal dust ones, we will try to co-relate what kind of particles are coming from where and quantify different parameters like PM10 (particulate matter), PM2.5, gaseous components, elemental and organic carbon and metal content in the air," said SK Goyal, senior principal scientist and head at Neeri's Delhi zonal centre.

According to scientists, this is the best period to monitor air as "stubble burning is in its prime". The real time pollution figures of PM2.5 and PM10, available on the Delhi Pollution Control Committee website, show that concentration of particulate matter in some areas is over five times more than the permissible limit. The permissible limit for PM2.5 is 60 microgram per cubic metre (mpcm) while for PM10 it is 100.

On Saturday evening, the PM10 levels at Wazirpur and Rohini exceeded 500 mpcm. At areas like Parparganj, Okhla, Sonia Vihar, both PM10 and PM2.5 were two-to-three times more than the safe limit.

Despite the National Green Tribunal (NGT) banning unabated burning of agricultural residue in Punjab and Haryana, huge quantities of stubble is being set afire by farmers. According to experts from the institute, an average of over 15 million tonnes of residue is burned in 15 days to make room for crops.

"The burning of huge quantity in lesser duration that, too in winters, is a major cause of concern. During this weather, the atmospheric capacity to disperse pollutants is lowest," Goyal said.

Apart from using mathematical modelling for studying wind direction, another component of the study is satellite imagery for which Neeri is seeking support of Indian Institute of Technology, Bombay. "Major 'heating points' where maximum burning is taking place will be captured along with the direction of fumes," Kumar said.

'Source profiling' will be carried out in the second phase of the study. "The pollutants which we are capturing are from a combination of different sources including industrial, vehicular and others. Hence with the help of source profiling, we will try to ascertain how much pollutants are emitted when a known quantity of crop is burned," Goyal added.

Source: Nov 5, 2017, The Times of India