A collaborative study led by the Indian Institute of Technology (IIT), Kanpur has linked the high amount of particulate pollution in Delhi during nightly hours to the biomass burning emissions.
The national capital routinely experiences high amounts of particulate pollution, also termed as haze. However the exact reason was hitherto unknown. The exhaustive research unearthed the reason behind severe haze events experienced during winters in Delhi, which is regarded as one of the world’s most-populated cities.
The study published in Nature Geoscience journal is led by IIT Kanpur and contributed by Physical Research Laboratory (PRL), IIT Delhi, Central Pollution Control Board (CPCB), Paul Scherrer Institut (PSI) Switzerland and University Helsinki, Finland.
The research paper is co-authored by Suneeti Mishra, and Prof Sachchida Nand Tripathi, from the Department of Civil Engineering, IIT Kanpur.
Prof Tripathi, the Principal Investigator in the study, said, “The uncontrolled biomass burning for residential heating and cooking in the Indo-Gangetic plain gives rise to ultrafine particles, affecting the health of 5 percent of the world’s population and impacting the regional climate.”
He said regulating uncontrolled biomass-combustion emissions may help inhibit nocturnal haze formation and improve health. “The study becomes important as air pollution is responsible for 18 percent of the total annual premature deaths in India.”
This study was designed for Delhi during the winter months of 2019 where aerosol size distribution and molecular composition of ambient aerosols and gases were measured. The measurements helped calculate growth of aerosols during night time along with the sources of aerosols and also the sources of gases.
The study found that ‘very high growth’ rates (tens of nano meter per hour) of aerosols especially for those smaller than 100 nanometers (nanoparticles) have been found in unfavourable new particle formation conditions compared to other places in the world.
The molecular information about aerosols showed that organic vapour from biomass burning contributed to the growth of nanoparticles. It also found that the composition of particles whose sizes were greater than 100 nanometer particles composition were dominated by ammonium and chloride species.
According to the IIT Kanpur, the study hinted that reduction of uncontrolled combustion, especially during conducive weather conditions, may limit the amount of supersaturated vapours available for nanoparticle growth and hence may be an effective strategy for the mitigation of nocturnal particulate number during haze in Delhi.