National ambient air quality standards


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Pollutants Time-weighted average

Concentration in ambient air

Method of measurement
    Industrial Areas Residential, Rural & other Areas Sensitive Are  
Sulphur Dioxide (SO2) Annual Average* 80 µg/m3 60 µg/m3
15 µg/m3
Improved West and Geake Method Ultraviolet Fluorescence
 
24 hours** 120 µg/m3 80 µg/m3 30 µg/m3 --
Oxides of Nitrogen as (NOx) Annual Average* 80 µg/m3 60 µg/m3 15 µg/m3 Jacob & Hochheiser Modified (Na-Arsenite) Method
24 hours** 120 µg/m3 80 µg/m3 30 µg/m3 Gas Phase Chemiluminescence
Suspended Particulate Matter (SPM) Annual Average* 360 µg/m3 140 µg/m3 70 µg/m3 High Volume Sampling, (Average flow rate not less than 1.1 m3/minute).
24 hours** 500 µg/m3 200 µg/m3 100 µg/m3 --
Respirable Particulate Matter (RPM) (size less than 10 microns) Annual Average* 120 µg/m3 60 µg/m3 50 µg/m3 Respirable particulate matter sampler
24 hours** 150 µg/m3 100 µg/m3 75 µg/m3 --
Lead (Pb) Annual Average* 1.0 µg/m3 0.75 µg/m3 0.50 µg/m3 ASS Method after sampling using EPM 2000 or equivalent Filter paper
24 hours** 1.5 µg/m3 1.00 µg/m3 0.75 µg/m3 --
Ammonia1 Annual Average* 0.1 mg/ m3 0.1 mg/ m3 0.1 mg/m3 --
24 hours** 0.4 mg/ m3 0.4 mg/ m3 0.4 mg/ m3 --
Carbon Monoxide (CO) 8 hours** 5.0 mg/m3 2.0 mg/m3 1.0 mg/ m3 Non Dispersive Infra Red (NDIR)
1 hour 10.0 mg/m3 4.0 mg/m3 2.0 mg/m3 Spectroscopy

 

(Source: Central Water Pollution Control Board, Ministry of Environment and Forests, Govt. of India)  Link to data source

*    Annual arithmetic mean of minimum 104 measurements in a year taken twice a week 24-hourly at uniform interval.
** 24-hourly/8-hourly values should be met 98% of the time in a year. However 2% of the time, it may exceeded but not two consecutive days.

Note :

1. National Ambient Air Quality Standards : The level of air quality necessary within an adequate margin of safety, to protect the public health, vegetation and property.
2. Whenever and wherever two consecutives value exceeds the limit specified above for the respective category, it would be considered adequate reason to institute regular/continuous monitoring and further investigations.