# The Air Quality Standards Regulations 2010, Schedule 2: Limit values


Sulphur dioxide
Averaging period
Limit value
One hour
350 μg/m3 not to be exceeded more than 24 times a calendar year
One day
125 μg/m3 not to be exceeded more than 3 times a calendar year
Nitrogen dioxide
Averaging period
Limit value
One hour
200 μg/m3 not to be exceeded more than 18 times a calendar year
Calendar year
40 μg/m3
Benzene
Averaging period
Limit value
Calendar year
5 µg/m3
Lead
Averaging period
Limit value
Calendar year
0.5 µg/m3
PM10
Averaging period
Limit value
One day
50 µg/m3, not to be exceeded more than 35 times a calendar year
Calendar year
40 µg/m3
PM2.5
Averaging Period
Limit Value
Date by which limit value is to be met
Calendar year
20 μg/m3
1st January 2020
Carbon monoxide
1 The maximum daily eight hour mean concentration of carbon monoxide must be selected by examining eight hour running averages, calculated from hourly data and updated each hour. Each eight hour average so calculated will be assigned to the day on which it ends, that is, the first calculation period for any one day will be from 17:00 on the previous day to 01:00 on that day, the last calculation period for any one day will be the period from 16:00 to 24:00 on that day.
Averaging period
Limit value
Maximum eight hour daily mean1
10 mg/m3

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Source: https://www.legislation.gov.uk/uksi/2010/1001/schedule/2 (the official version)
Page: https://openlegislation.uk/air-quality-standards-regulations-2010/schedule-2
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.