In a 2018 study, New Delhi was found to be the most polluted capital out of 61 capital cities around the world. In December 2019, IIT Bombay, in partnership with the McKelvey School of Engineering of Washington University in St. Louis, launched the Aerosol and Air Quality Research Facility to study air pollution in New Delhi, among other Indian cities. During the COVID-19 pandemic lockdown in India, the water quality of the Yamuna and Ganges river basins have improved as industries are closed due to the lockdown. The air quality has also significantly improved during the lockdown. On 5 November 2020, New Delhi recorded its most toxic day in a year, as the concentration of poisonous PM2.5 particles was recorded at 14 times the WHO's safe limit.
In a 2018 study, New Delhi was found to be the most polluted capital out of 61 capital cities around the world. In December 2019, IIT Bombay, in partnership with the McKelvey School of Engineering of Washington University in St. Louis, launched the Aerosol and Air Quality Research Facility to study air pollution in New Delhi, among other Indian cities. During the COVID-19 pandemic lockdown in India, the water quality of the Yamuna and Ganges river basins have improved as industries are closed due to the lockdown. The air quality has also significantly improved during the lockdown. On 5 November 2020, New Delhi recorded its most toxic day in a year, as the concentration of poisonous PM2.5 particles was recorded at 14 times the WHO's safe limit.