Air Quality Regulations (Northern Ireland) 2003

Regulation 3(2) and 4(1)

SCHEDULE Air Quality Objectives

Pollutant	Air Quality objective levels*	Date to be achieved by
(1)	(2)	(3)
* μg/m3: micrograms per cubic metre ppb/ppm: parts per billion/million mg/m3: milligrams per cubic metre
Benzene	16.25μg/m3 (5ppb) when expressed as a running annual mean	31 December 2003
	3.25μg/m3 when expressed as a running annual mean	31 December 2010
1,3-butadiene	2.25μg/m3 (1ppb) when expressed as a running annual mean	31 December 2003
Carbon monoxide	10mg/m3 (8.6ppm) when expressed as a maximum daily running 8 hour mean	31 December 2003
Lead	0.5μg/m3 when expressed as an annual mean	31 December 2004
	0.25mg/m3 when expressed as an annual mean	31 December 2008
Nitrogen dioxide	200μg/m3 (105ppb) when expressed as a 1 hour mean, not to be exceeded more than 18 times a year	31 December 2005
	40μg/m3 (21ppb) when expressed as an annual mean	31 December 2005
Sulphur dioxide	35μg/m3 (132ppb) when expressed as a 1 hour mean, not to be exceeded more than 24 times a year	31 December 2004
	125μg/m3 (47ppb) when expressed as a 24 hour mean, not to be exceeded more than 3 times a year	31 December 2004
	266μg/m3 (100ppb) when expressed as a 15 minute mean, not to be exceeded more than 35 times a year	31 December 2005
Particles (PM10)	50μg/m3 when expressed as a 24 hour mean, not to be exceeded more than 35 times a year	31 December 2004
	40μg/m3 when expressed as an annual mean	31 December 2004

Interpretation

For the purposes of this schedule:–

1.  “PM₁₀” means particulate matter, which passes through a size-selective inlet with a 50% efficiency cut-off at 10μm aerodynamic diameter.

2.—(1) A running annual mean is a mean, which is calculated on an hourly basis, yielding one running annual mean per hour. The running annual mean for a particular substance at a particular location for a particular hour is the mean of the hourly levels for that substance at that location for that hour and the preceding 8759 hours.

(2) For the purpose of the calculation of a running annual mean, the hourly level for a particular substance at a particular location is either –

(a) the level at which that substance is recorded as being present in the air at that location during the hour on the basis of a continuous sample of air taken during that hour for at least 30 minutes: or

(b) the mean of the levels recorded at that location on the basis of 2 or more samples of air taken during the hour for an aggregate period of at least 30 minutes.

3.—(1) A maximum daily running 8-hour mean is calculated on a daily basis. The maximum daily running 8-hour mean for a particular substance at a particular location for a particular day is the maximum of the running 8-hour means ending during that day.

(2) For the purpose of sub-paragraph (1) a “running 8-hour mean” is a mean, which is calculated on an hourly basis, yielding one running 8 hour mean per hour. The running 8-hour mean for the relevant substance at the relevant location for a particular hour is the mean of the hourly means for the substance at the location for the hour and the preceding 7 hours.

4.—(1) An annual mean is a mean, which is calculated on a yearly basis, yielding one annual mean per calendar year. The annual mean for a particular substance at a particular location for a particular calendar year is –

(a) in the case of lead, the mean of the daily levels for that year;

(b) in the case of nitrogen dioxide, the mean of the hourly means for that year;

(c) in the case of PM₁₀, the mean of the 24-hour means for that year;

(d) in the case of benzene, either the mean of the daily levels for that year or the mean of the hourly means for that year.

(2) For the purpose of the calculation of the annual mean for lead, the daily level for lead at a particular location for a particular day is the level at which lead is recorded as being present in the air at that location during the week in which the day occurs on the basis of a continuous sample of air taken throughout that week (each day in that week therefore being attributed with the same daily level).

(3) For the purpose of sub-paragraph (2) “week” means a complete week beginning on a Monday, except that it also includes any period of less than seven days from the beginning of the calendar year until the first Monday in that year to the end of that year.

(4) For the purpose of any calculation of the annual mean for benzene on the basis of the mean of the daily levels, the daily level for benzene at a particular location for a particular day is the level at which benzene is recorded as being present in the air at that location during the fortnight in which the day occurs on the basis of a continuous sample of air taken throughout that fortnight (each day in the fortnight therefore being attributed with the same daily level).

(5) For the purpose of sub-paragraph (4) “fortnight” means a complete fortnight, that is a period of two weeks beginning on a Monday (no particular week in a calendar year being included in more than one fortnight), except that it also includes –

(a) in any calendar year beginning on a day other than a Monday, the period from the beginning of the year until the first Monday in that year; and

(b) in any year, the period from the end of the last complete fortnight in the year to the end of that year.

5.  An hourly mean is a mean calculated every hour. The hourly mean for a particular substance at a particular location for a particular hour is the mean of the levels recorded for that substance at that location –

(a) in the case of benzene, at a frequency of not less than once during the hour; and

(b) in the case of carbon monoxide, nitrogen dioxide and sulphur dioxide, at a frequency of not less than once every 10 seconds during the hour.

6.  A 24-hour mean is a mean calculated every 24 hours. The 24 hour mean for a particular substance at a particular location for a particular 24 hour period is the level at which that substance is recorded as being present in the air at that location on the basis of a continuous sample of air taken throughout the period.

7.  A 15-minute mean is a mean calculated every 15 minutes. The 15 minute mean for a particular substance at a particular location for a particular 15 minutes is the mean of the levels recorded, at a frequency of not les than once every 10 seconds, for that substance at that location during that 15 minutes.

8.  The reference to a number of micrograms or milligrams per cubic metre of a substance is a reference to the number of micrograms or milligrams per cubic metre of that substance when measured with the volume standardised at a temperature of 293K and at a pressure of 101.3 kPa.