# The Air Quality Standards Regulations (Northern Ireland) 2010, Schedule 2: Limit values

Extent: N.I.

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
Carbon monoxide
Averaging period
Limit value
(1)The maximum daily eight hour mean concentration of carbon monoxide shall 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, i.e. the first calculation period for any one day will be the period 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.
Maximum daily eight hour mean
10 mg/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
Margin of tolerance
Date by which limit value is to be met
Calendar year
25 µg/m3
20% on 11 June 2008, decreasing on the next 1 January and every 12 months thereafter by equal annual percentages to reach 0% by 1 January 2015
1 January 2015

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Source: https://www.legislation.gov.uk/nisr/2010/188/schedule/2 (the official version)
Page: https://openlegislation.uk/air-quality-standards-regulations-northern-ireland-2010/schedule-2
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.