# The Air Quality Limit Values Regulations (Northern Ireland) 2002, Part I: UPPER AND LOWER ASSESSMENT THRESHOLDS

Extent: N.I.

The following upper and lower assessment thresholds will apply:
(a) SULPHUR DIOXIDE
Health protection
Ecosystem protection
Upper assessment threshold
60% of 24-hour limit value (75 μg/m3) not to be exceeded more than 3 times in any calendar year
60% of winter limit value (12 μg/m3)
Lower assessment threshold
40% of 24-hour limit value (50 μg/m3) not to be exceeded more than 3 times in any calendar year
40% of winter limit value (8 μg/m3)
(b) NITROGEN DIOXIDE AND OXIDES OF NITROGEN
Hourly limit value for the protection of human health (NO2)
Annual limit value for the protection of human health (NO2)
Annual limit value for the protection of vegetation (NOx)
Upper assessment threshold
70% of limit value (140 μg/m3) not to be exceeded more than 18 times in any calendar year
80% of limit value (32 μg/m3)
80% of limit value (24 μg/m3)
Lower assessment threshold
50% of limit value (100 μg/m3) not to be exceeded more than 18 times in any calendar year
65% of limit value (26 μg/m3)
65% of limit value (19.5 μg/m3)
(c) PARTICULATE MATTER
24-hour average
Annual average
Upper assessment threshold
60% of limit value (30 μg/m3) not to be exceeded more than 7 times in any calendar year
70% of limit value (14 μg/m3)
Lower assessment threshold
40% of limit value (20 μg/m3) not to be exceeded more than 7 times in any calendar year
50% of limit value (10 μg/m3)
Averaging Period
Limit Value
Margin of tolerance
Date by which limit value is to be met
1 24-hour limit value for the protection of human health
24 hours
50mg/m3 PM10 not to be exceeded more than 7 times a calendar year
To be derived from data and to be equivalent to Stage 1 limit value.
1st January 2010
2 Annual limit value for the protection of human health
Calendar year
20 mg/m3 PM10
50% on 1st January 2005 reducing every 12 months thereafter by equal annual percentages to reach 0% by 1st January 2010
1st January 2010
(d) LEAD
Annual average
Upper assessment threshold
70% of limit value (0.35 μg/m3)
Lower assessment threshold
50% of limit value (0.25 μg/m3)

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Source: https://www.legislation.gov.uk/nisr/2002/94/schedule/2/part/I (the official version)
Page: https://openlegislation.uk/air-quality-limit-values-regulations-northern-ireland-2002/schedule-2/part-I
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.