Delhi has been declared the most polluted capital in the world in terms of air quality for the fourth year in a row in 2021, reveals a new report which says 35 out of 50 cities with worst air quality were in India.
The World Air Quality Report released Tuesday by Swiss organization IQAir is based on PM2.5 data from 6,475 cities in 117 countries. The dataset used to generate this report was derived from the IQAir real-time online air quality monitoring platform, which aggregates, validates, calibrates, and harmonizes data from air quality monitoring stations around the globe.
The report said that publicly available air quality monitoring station data continued to increase in 2021. India, New Zealand, and Canada, in particular, saw significant increases.
Air pollution has a massive impact on human health in India. The researchers said, “India was home to 11 of the 15 most polluted cities in Central and South Asia in 2021. Delhi saw a 14.6 per cent increase in PM2.5 concentrations in 2021 with levels rising to 96.4 ug/m3 from 84 ug/m3 in 2020. No cities in India met the WHO air quality guideline of 5 ug/m3. In 2021, 48% of India’s cities exceeded 50 ug/m3, or more than 10 times the WHO guideline.”
Air pollution causes and aggravates many diseases, ranging from asthma to cancer, lung illnesses and heart disease and in this age of COVID-19, researchers have found that exposure to PM2.5 increases both the risk of contracting the virus and of suffering more severe symptoms when infected, including death.
For the increased pollution concentration in Delhi, India, the researchers said the country’s “annual average PM2.5 levels reached 58.1 ug/m3 in 2021, ending a three-year trend of improving air quality. India’s annual PM2.5 averages have now returned to pre-quarantine concentrations measured in 2019.”
The report weighed that major sources of air pollution in India include vehicular emissions, power generation, industrial waste, biomass combustion for cooking, the construction sector, and episodic events like crop burning.
Researchers also found that the air quality improved in China as more than half of the cities in the country included in the report saw lower levels of air pollution when compared to the previous year.