PMF IAS Current Affairs
PMF IAS Current Affairs

Air Quality Index (AQI), Air Quality Monitoring & National Ambient Air Quality Standards (NAAQS)

Air Quality Monitoring

  • Context (PIB): Delhi records its lowest average Air Quality Index (AQI) during July 2023 compared to the corresponding period of the last 04 years from 2019.

National Air Quality Monitoring Programme

  • The Central Pollution Control Board (CPCB) has been executing a nationwide ambient air quality monitoring programme known as National Air Quality Monitoring Programme (NAMP).
  • NAMP network comprises 800+ operating stations covering 344 cities/towns in 28 states and 6 UTs.
  • NAMP is undertaken to determine the status and trends of ambient air quality, ascertain the compliance of NAAQS, identify non-attainment cities, etc.
  • Under NAMP, Sulphur Dioxide (SO2), Oxides of Nitrogen (NO2), Respirable Suspended Particulate Matter (PM10) and Fine Particulate Matter (PM2.5) are regularly monitored.
  • The monitoring of wind speed and direction, relative humidity and temperature were also integrated with the monitoring of air quality.

National Ambient Air Quality Standards (NAAQS)

  • NAAQS are standards for air quality set up by CPCB in 2009.
  • The CPCB has been conferred this power by the Air (Prevention & Control of Pollution) Act, 1981.
  • NAAQS consists of twelve pollutants.

National Ambient Air Quality Standards, as of 2009

Pollutants (12) Time Weighted


Concentration in Ambient Air

Industrial, Residential, Rural & Other Area Ecologically Sensitive Area (notified by GOI)
SO2, μg/m3 Annual 50 20
24 hours 80 80
NO2, μg/m3 Annual 40 30
24 hours 80 80
PM10, μg/m3 Annual 60 60
24 hours 100 100
PM2.5, μg/m3 Annual 40 40
24 hours 60 60
O3, μg/m3 8 hours 100 100
1 hour 180 180
Lead (Pb), μg/m3 Annual 0.50 0.50
24 hours 1 1
CO, mg/m3 8 hours 2 2
1 hour 4 4
Ammonia (NH3), μg/m3 Annual 100 100
24 hours 400 400
Benzene, μg/m3 Annual 5 5
Benzopyrene, μg/m3 Annual 1 1
Arsenic (As), ng/m3 Annual 6 6
Nickel (Ni), ng/m3 Annual 20 20

Air Quality Index

  • AQI was launched in 2014 with an outline One Number – One Color One Description’ for the common man to judge the air quality within his vicinity.
  • It has been developed by Central Pollution Control Board (CPCB).
  • AQI is based on eight pollutants, namely:
    1. Particulate Matter (PM10)
    2. Particulate Matter (PM2.5)
    3. Nitrogen Dioxide (NO2)
    4. Sulphur Dioxide (SO2)
    5. Carbon Monoxide (CO)
    6. Ozone (O3)
    7. Ammonia (NH3)
    8. Lead (Pb)
  • AQI has six categories of air quality.

Air Quality Index

2021 WHO Air Quality Guidelines (AQGs)

  • WHO has released an updated version of the Global Air Quality Guidelines (AQGs).
  • The guidelines consider how air pollution damages human health at even lower concentrations.
Pollutants (6) Averaging Time


2021 AQGs

PM2.5, μg/m3 Annual



24-hour mean



PM10, μg/m3 Annual



24-hour mean



O3, μg/m3 Peak season


8-hour mean



NO2, μg/m3 Annual



24-hour mean


SO2, μg/m3 24-hour mean



CO, μg/m3 24-hour mean


WHO Ambient Air Quality Database

  • The air quality database is a compilation of data on air quality and the concentrations of PM.
  • It compiles ground measurements of annual mean concentrations of NO2, PM10 and PM2.5.
  • It was started in 2011 and has since then been periodically updated.
  • Its update in 2023 is the sixth update to the database.

Fifth update (2022)

  • For the first time, in the fifth update, the database contains the ground measurements of nitrogen dioxide, which the WHO calls “a common urban pollutant and precursor of PM and ozone.”
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