National Ambient Air Quality Standards
Pollutants
Time-weighted average
Concentration in ambient air
Method of measurement
Industrial Areas
Residential, Rural & other Areas
Sensitive Areas
SulphurDioxide (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
RespirableParticulate 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
.
CarbonMonoxide (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


*

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 exceed but not on two consecutive days.