Ambient Air Quality Standards

Air quality standards for selected polluting substances
 

Polluting substance		Air quality standards (µ g.m-3)
	Expressed as	AQSy	AQSd	AQS8h	AQSs
Particulate matter		60	150		500
Sulphur dioxide	SO2	60	150		500
Sulphur dioxide and particulate matter	SO2 + p.p.		250*
Nitrogen oxides	NO2	80	100		200
Carbon monoxide	CO		5 000		10 000
Ozone	O3			110
Lead in particulate matter	Pb	0.5
Cadmium in particulate matter	Cd	0.01
Malodours substance		must not occur in concentrations to be public nuisance

* Calculated arithmetic sum of both components daily averages concentration

Explanation of symbols:

AQS_y: average annual concentration of the polluting substance. Average concentration is a mean concentration level recorded at a designated point within a span of one year. The result is given in the form of an arithmetic mean calculated from average daily concentrations

AQS_d:average daily concentration of the polluting substance. Average daily concentration is a mean concentration level recorded at a designated point within a pan of 24 hours. Average daily concentration is also understood as the mean of at least 12 (periodical) average concentration levels recorded every 30 minutes within a span of 24 hours (arithmetic mean)

AQS_8h: average 8-hour-concentration of the polluting substance. Average 8-hour-concentration is a mean concentration level recorded at a designated point within a span of 8 hours

AQS_s: average 30-minute-concentration of the polluting substance .Average 30-minute-concentration is a mean concentration level recorded at a designated point within a span of 30 minutes

Limiting criteria: AQS_d and AQS_S for particulate matter, SO₂, No_x and CO cannot be exceeded in the course of the year in more than 5% of cases.