National Air Quality Index (AQI)

Why in news?
Launched in April 2015 by the PM.

Why was it launched?

• for monitoring the quality of air in major urban centres across the country on a real-time basis and 
• enhancing public awareness for taking mitigative action
• create a competitive environment among cities to take steps for air pollution-mitigation

The AQI

• The air quality index from the Central Pollution Control Board is the first national index to explain in layman’s terms the effect that breathing the air in 10 cities could have on a person’s health.
• The AQI has six categories of air quality, viz Good, Satisfactory, Moderately polluted, Poor, Very Poor and Severe with distinct colour scheme. Each of these categories is associated with likely health impacts
• The AQI has been at present launched for 10 cities -- Delhi, Agra, Kanpur, Lucknow, Varanasi, Faridabad, Ahmedabad, Chennai, Bangalore and Hyderabad. 
• It will have 'one number, one colour and one description' to inform the public about air quality in a simple and easily understandable format. 
• Each of these cities will have 6-7 continuous monitoring stations with AQI display boards.

Source: Times of India

The Pollutants

• AQI considers eight pollutants (PM10, PM 2.5, NO2, SO2, CO, O3, NH3 and Pb) 
• The new National Air Quality Index gives current as well as 24-hour average data on particulate matter – 
• PM2.5 or very fine particles smaller than 2.5 micrometres in diameter, and 
• PM 10 which are less than 10 micrometers in diameter – as well as 
• other pollutants including nitrogen dioxide, ozone and carbon monoxide. 
• PM 2.5 levels are commonly used as the best indicator of severe air pollution, while PM 10 particles are also a cause of public health concern, but less lethal.

Source: Mrunal.org

Benefits

• India has joined the global league of countries like the US, China, Mexico and France that have implemented smog alert systems.
• Awareness among masses
• Real-time information
• Assist policy making 

Critical appraisal of AQI

• The location and quality of instruments used at monitoring sites need to be proper.
• One index to be used across India. 
• Separate indexes for residential, industrial, urban, rural, etc. areas would have been better
• E.g. - In villages methane content is usually high due to open compost pits and cattles. 
• The AQI is only based on 8 pollutants. Methane, Benzene (USA does) (basically NMVOC not included - non methane volatile organic compound), etc. are not being monitored. 
• Only informing masses might not be enough. Daily advisories should also be issued. (China- red level - primary schools are shut)

[Sources: The Times of India, DNA, The Hindu, PIB]