NEW DELHI: Burning of plastic waste is primarily responsible for haze and fog formation in northern India, including national capital Delhi, according to a study led by researchers from the Indian Institute of Technology Madras (IIT-M). The Study has been published in the international journal Nature Geoscience.
Many studies in the past have identified PM2.5 (particulate matter or aerosol particles with diameter less than 2.5 micrometre) as a major pollutant, responsible for haze and fog formation over Indo-Gangetic plain including Delhi. However, the role of PM2.5 and detailed chemistry of haze and fog formation over national capital was poorly understood.
The study explains that complex chemical reactions involving Hydrochloric Acid (HCl), which is directly emitted in the atmosphere from burning of plastic waste and from a few industrial processes, is primarily responsible for high PM2.5 chloride and subsequent haze and fog formation over Delhi during chilly winter nights.
While previous researchers also have observed high chloride in PM2.5, the potential source of such a high chloride and if it played any role in haze and fog formation was a scientific mystery. The study, led by IIT-M, was carried out in collaboration with researchers from Max Planck Institute for Chemistry, Germany; Harvard University, USA; Georgia Institute of Technology, USA; and Manchester University, UK.
The group of scientists and students deployed state-of-the-art instruments to measure the chemical composition and other important properties of PM2.5, along with relative humidity and temperature in Delhi. The data was collected round-the-clock for one month with extreme care and dedicated expertise. The observations were then used in complex chemical models.