Delhi worst in PM2.5 concentration: Study, Pg4

Key Highlights:

• Delhi tops the list of most polluted states/UTs in India with an annual mean PM2.5 concentration of 101 µg/m3, which is 2.5 times the national limit.
• 60% of India's 749 districts exceed the annual National Ambient Air Quality Standards (NAAQS) of 40 µg/m³.
• The Indo-Gangetic airshed is the most polluted region in the country, showing consistent non-compliance across seasons.
• Assam and Tripura in the Northeast airshed face year-round air quality challenges with elevated PM2.5 concentrations.

Detailed Insights:

• The study, conducted by the Centre for Research on Energy and Clean Air (CREA), used satellite and ground data to map population-weighted PM2.5 levels across India.
• PM2.5 concentrations vary widely, from 21 µg/m³ in Tiruppur, Tamil Nadu, to 112 µg/m³ in North West district of Delhi.
• While most airsheds see improved air quality during the monsoon season due to atmospheric cleansing, the Assam-Tripura airshed remains an exception.
• The report highlights that state-level averages can mask local hotspots, citing Maharashtra, where several districts exceed NAAQS despite the state mean being near the standard.
• The study emphasizes that baseline emissions, rather than meteorology, are the primary cause of non-compliance with air quality standards.

Key Concepts Involved:

• PM2.5: Fine particulate matter with a diameter of 2.5 micrometers or less, posing significant health risks due to its ability to enter the bloodstream.
• NAAQS (National Ambient Air Quality Standards): Standards set by the government for ambient air quality to protect public health and the environment.
• Airshed: A geographical area that shares a common flow of air, often used for air quality management and monitoring.