About the Report

• The World Air Quality Report is prepared by Swiss organization IQAir.
• The report is based on PM2.5 air quality data from 6,475 cities in 117 countries, regions and territories around the world.
• IQAir endeavors to engage, educate, and inspire governments, researchers, NGOs, companies, and citizens to work together to improve air quality and create healthier communities and cities.

Key Findings

• No country met the latest WHO air quality guideline for PM2.5 in 2021.

• The WHO recommends that average annual readings of small and hazardous airborne particles known as PM2.5 should be no more than 5 micrograms per cubic metre after changing its guidelines last year, saying that even low concentrations caused significant health risks.

• • Only the territories of New Caledonia, U.S. Virgin Islands and Puerto Rico met updated WHO PM2.5 air quality guidelines.
  • Only 222 out of 6,475 global cities covered in the report met the updated WHO PM2.5 guideline.
  • 93 cities in the report had annual PM2.5 concentrations exceeding 10 times the WHO PM2.5 guideline.
  • China, which has been waging war on pollution since 2014, fell to 22nd in the PM2.5 rankings in 2021, down from 14th place a year earlier, with average readings improving slightly over the year to 32.6 micrograms.
  • Hotan in the northwestern region of Xinjiang was China’s worst-performing city, with average PM2.5 readings of more than 100 micrograms, largely caused by sandstorms.
  • Central and South Asia had some of the world’s worst air quality in 2021 and was home to 46 of the world’s 50 most polluted cities.

• The top five most polluted countries in 2021 were:

• • Bangladesh
  • Chad
  • Pakistan
  • Tajikistan
  • India

Indian Scenario

• New Delhi (India) is the world’s most polluted capital city for the fourth consecutive year followed by Dhaka (Bangladesh), N’Djamena (Chad), Dushanbe (Tajikistan) and Muscat (Oman).
• The report added that 35 of the 50 cities with the worst air quality were in India with Rajasthan’s Bhiwadi topping the list followed closely by Uttar Pradesh’s Ghaziabad.
• None of the cities in India met the prescribed World Health Organization (WHO) air quality standards of 5 micrograms per cubic meter.
• India’s annual average PM2.5 levels reached 58.1 μg/m3 in 2021, ending a three-year trend of improving air quality
• The report also revealed that 48 per cent of Indian cities exceeded 50 μg/m3 air quality level which is well over 10 times the WHO guidelines.

Why is air pollution a cause for concern?

• According to the report’s executive summary, air pollution is now considered to be the world’s largest environmental health threat, accounting for seven million deaths around the world every year.
• Air pollution causes and aggravates many diseases, ranging from asthma to cancer, lung illnesses and heart disease. 
• The estimated daily economic cost of air pollution has been figured at $8 billion (USD), or 3 to 4 percent of the gross world product.
• The report noted that In India, major sources of air pollution include vehicular emissions, power generation, industrial waste, biomass combustion for cooking, the construction sector, and episodic events like crop burning.

References:

1. https://www.hindustantimes.com/environment/these-are-20-most-polluted-cities-in-the-world-rajasthan-city-tops-the-list-101647954069826.html
2. https://www.hindustantimes.com/environment/delhi-is-world-s-most-polluted-capital-35-indian-cities-in-top-50-report-101647942197554.html
3. https://www.iqair.com/blog/press-releases/WAQR_2021_PR
4. https://indianexpress.com/article/lifestyle/health/35-indian-cities-50-world-most-polluted-air-pollution-quality-aqi-pm-levels-7832341/