Delhi, the 11^th April, 1994

S.O. 384(E). -The Central Pollution Control Board in exercise of its powers conferred under section 16 (2) (h) of the Air (Prevention and Control of Pollution) Act,1981(14 of 1981) hereby notify the National Ambient Air Quality Standards with immediate effect.

Pollutant	Time Weighted average	Concentration in ambient air			Method of measurement
		Industrial Area	Residential. Rural & other areas,	Sensitive Area
1	2	3	4	5	6
Sulphur Dioxide (SO2 )	Annual Average*	80 m g/m³	60m g/m ³	15 µg/m³	Improved West and Gacke method
	24 hours **	120 µg/m³	80 µg/m³	30µg/m³	Ultraviolet fluorescence
Oxides of Nitrogen as N02	Annual Average*	80 m g/m³	60m g/m ³	15 µg/m³	Jacob & Hochheiser modified ( Na-Arsenite) Method
	24 hours **	120 µg/m³	80 µg/m³	30µg/m³	Gas Phase Chemiluminescence
Suspended Particulate Matter (SPM)	Annual Average*	360 µg/m³	140 µg/m³	70 µg/m³	(Average flow rate not less than 1.1 m ³/minute)
	24 hours **	500 µg/m³	200 µg/m³	100 µg/m³
Respirable Particulate matter (size less than10 um)(RPM)	Annual Average*	120 µg/m³	60m g/m ³	50m g/m ³
	24 hours **	150m g/m ³	100m g/m ³	75m g/m ³
Lead (Pb)	Annual Average*	1.0m g/m ³	0.75m g/m ³	0.50m g/m ³	AAS Method after sampling using EPM 2000 or equivalent filter paper
	24 hours **	1.5m g/m ³	1.00m g/m ³	0.75m g/m ³
Carbon Monoxide (CO)	8 hours	5.0m g/m ³	2.0m g/m ³	1.0m g/m ³	Non dispersive infrared spectroscopy
	I hour	10.0m g/m ³	4.0m g/m ³	2.0m g/m ³

* Annual Arithmetic mean of minimum 104 measurements in a year taken twice a week 24 hourly at uniform interval

** 24 boudy/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.

a. National Ambient Air Quality Standard: The levels of air quality necessary with an adequate margin of safety, to protect the public health, vegetation and property.