Delhi, Kolkata most polluted cities globally by PM2.5

In News: According to a report titled Air Quality and Health in Cities, published by the United States-based Health Effects Institute, Delhi and Kolkata are the top two most polluted cities in terms of exposure to harmful fine particulate matter (PM2.5).

• The report examines pollution and global health implications in over 7,000 cities worldwide, focussing on two of the most dangerous pollutants – fine particulate matter (PM2.5) and nitrogen dioxide (NO2).

Overall findings of the Air Quality and Health in Cities report:

• According to the report, while exposures to 5 and NO2 pollution tend to be higher in cities located in low and middle-income countries,
• The report found most global cities far exceed World Health Organisation’s (WHO) air pollution guidelines, posing serious health risk.
  • In 2019, 86% of the cities analysed exceeded the WHO’s 10 µg/m3 (microgram per cubic metre) guideline for NO2, impacting about 2.6 billion people.
• 41 of the 50 cities with the highest increase in PM2.5 are in India, with 9 in Indonesia.
• On the other hand, all 20 cities with the highest reduction in PM2.5 pollution from 2010 to 2019 are in China.

India specific findings:

• Delhi and Kolkata were ranked first and second in the list of top 10 most polluted cities when PM2.5 levels were compared.
  • In terms of impact, Delhi and Kolkata ranked sixth and eighth for PM2.5 related disease burden, reporting 106 deaths and 99 deaths per lakh of population, respectively due to exposure to 5 in 2019.
• However, no Indian city appeared in the list of top 20 polluted cities when N02 levels were compared (Shanghai at the top with an average annual exposure of 41 µg/m3).

Short-lived climate pollutants: Short-lived climate pollutants (SLCPs) are powerful climate forcers that remain in the atmosphere for a much shorter period than longer-lived climate pollutants, such as carbon dioxide (CO2). They include methane, PM 2.5, NO2, fluorinated gases including hydrofluorocarbons (HFCs), and black carbon.

Source: The Hindu

Indian Express

Previous Year Question

Q.1) Among the following crops, which one is the most important anthropogenic source of both methane and nitrous oxide? (2022)

1. Cotton
2. Rice
3. Sugarcane
4. Wheat