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 Average	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.

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 2005 2021 AQGs PM2.5, μg/m3 Annual 10 5 24-hour mean 25 15 PM10, μg/m3 Annual 20 15 24-hour mean 50 45 O3, μg/m3 Peak season – 60 8-hour mean 100 100 NO2, μg/m3 Annual 40 10 24-hour mean 25 SO2, μg/m3 24-hour mean 20 40 CO, μg/m3 24-hour mean – 4 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.”