World Air Quality Report 2021 Released

[GS Paper 3 – Environmental Pollution]

Delhi ranked as the most polluted out of 107 capital cities in the world, according to the 2021 World Air Quality Report. The city is topping the list for the fourth consecutive year. Delhi topped a list of 92 capital cities in 2020, 85 such cities in 2019, and 62 such cities in 2018.

Key Highlights of the Report

• As per the reports, India is home to 11 of the 15 most polluted cities in Central and South Asia Delhi saw a 14.6% increase in PM2.5 concentrations in 2021 with levels rising to 96.4 µg/m3 from 84 µg/m3 in 2020. 
• No cities in India met the WHO air quality guideline of 5 µg/m3. In 2021, 48% of India’s cities exceeded 50 µg/m3, or more than 10 times the WHO guideline.
• In the Central and South Asia region – Bhiwadi, in Alwar district, Rajasthan, was the most polluted regional city, with an average PM2.5 concentration of 106.2 50 µg/m3. This was followed by Ghaziabad with 102 µg/m3, and then Delhi with 96.4 µg/m3.
• Sources of PM2.5 “include internal combustion engines, power generation, industrial processes, agricultural processes, construction, and residential wood and coal burning. The most common natural sources for PM2.5 are dust storms, sandstorms, and wildfires.

About PM 2.5

• It is an atmospheric particulate matter of diameter of fewer than 2.5 micrometers, which is around 3% the diameter of a human hair.
• It causes respiratory problems and also reduces visibility. It is an endocrine disruptor that can affect insulin secretion and insulin sensitivity, thus contributing to diabetes.
• It is very small and can only be detected with the help of an electron microscope.
• Some are emitted directly from a source, such as construction sites, unpaved roads, fields, smokestacks or fires.

About the Report

• The World Air Quality Report is based on PM2.5 data from 6,475 locations in 117 countries, regions and territories around the world, and is prepared by IQAir, a Swiss air quality technology company. 
• The report draws data from government-operated monitoring stations as well as privately-owned ones, and monitoring stations operated by institutions.

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