Executive Summary

This report presents a summary of air quality in Northern Ireland over the calendar years 2000 and 2001. It is intended to bring together in one report, results from all the District Councils and other organisations who carried out air quality measurements in Northern Ireland over this period, both as part of larger monitoring networks and for other purposes. It aims to provide information on the main pollutants of concern, details of the air quality monitoring undertaken in 2000 – 2001, and a summary of results for each pollutant.

On the basis of results from 2000 and 2001, the following pollutants appear not to present a problem with respect to meeting air quality objectives in Northern Ireland: carbon monoxide (CO), particulate matter (PM₁₀), benzene, 1,3-butadiene, lead and other metals. Occasional exceedences may occur in the case of ozone, particularly in rural locations. However, these are likely to be infrequent, and related to meteorological conditions; ozone is, in any case, a transboundary pollutant and difficult to control by local action.

The monitoring results indicate that the following pollutants may present a problem in meeting air quality objectives, in some parts of Northern Ireland:

· Sulphur dioxide: in residential areas where there is a high incidence of domestic solid fuel burning, there may be difficulty in meeting objectives relating to the 15-minute and 24-hour means.

· Benzo(a)pyrene and other polycyclic aromatic hydrocarbons (PAHs), again in solid-fuel burning residential areas.

· Possibly nitrogen dioxide (NO₂) at a few urban roadside locations.

Historically, there has been limited availability of natural gas in Northern Ireland, which has necessitated the widespread domestic use of solid fuels and oil. Inevitably, this has led to some residential areas having relatively high levels of pollutants associated with coal burning (sulphur dioxide, PAHs and in some cases smoke). Therefore, these remain the pollutants of concern for some parts of the region. However, as natural gas becomes more widely used in Northern Ireland, it is likely that ambient concentrations of these pollutants will decrease.

Carbon monoxide was monitored using automatic techniques at two sites (Belfast and Londonderry). Both met the EC 2^nd Daughter Directive limit value and UK Air Quality Strategy (AQS) objective for this pollutant in 2000 and 2001.

Nitrogen dioxide was monitored using the automatic chemiluminescent technique at four sites: Belfast Centre, Londonderry and two in Newry. No sites exceeded the 1^st Daughter Directive limit and AQS objective of 200 µg m^-3 for the hourly mean, more than the permitted 18 times per year in 2000 or 2001. The annual mean was found to be below the limit value of 40 µg m^-3 at all four sites.

Nitrogen dioxide was also monitored on a monthly basis using passive diffusion tube samplers at 128 sites in 2000 and 155 sites in 2001. The EC 1^st Daughter Directive limit value and AQS objective for the annual mean (40 µg m^-3) was exceeded at four sites in 2000 (three Roadside and one Intermediate), and at six sites in 2001 (all Roadside). All these sites were either in urban centres close to busy main roads, or in smaller town centres at locations where traffic queues form. Annual average NO₂ concentrations for 2000 and 2001 were comparable to those reported by the NO₂ Network for Northern Ireland.

Sulphur Dioxide (SO₂) was monitored at five sites (central and eastern Belfast, Londonderry and two in Newry) using automatic techniques. All automatic sites except Belfast East met the 1^st Daughter Directive limit values and AQS objectives. Belfast East exceeded the AQS objective for the 15-minute mean in both 2000 and 2001, and exceeded the EC 1^st Daughter Directive limit value and AQS objective for the 24-hour mean in 2001. This site (and possibly similar locations) may have difficulty in meeting this EC limit value and these AQS objectives for sulphur dioxide by the required dates in 2004 and 2005.

A further 31 urban sites monitored sulphur dioxide using the non-automatic net acidity method. In 2000, one site in Dunmurry exceeded the 24-hour limit value for SO₂ (125 µg m^-3) on more than the permitted three days. In 2001, three sites in Belfast exceeded this limit value on more than three days. The 2001 exceedences were associated with episodes of high SO₂ during January and February 2001.

Particulate matter as PM₁₀ was monitored at six sites (two in Belfast, one in Londonderry, two in Newry and one rural location, Lough Navar). All of these met the EC 1^st Daughter Directive limits and Air Quality Strategy objectives relating to annual and daily averages, for PM₁₀.

Particulate matter was also measured using the older “black smoke” method, at 31 urban sites. The limits set for smoke by EC Directive 80/779/EEC (on sulphur dioxide and suspended particulates) remain in force until 2005, and require demonstration of compliance. No Northern Ireland sites have exceeded any of the limit values of Directive 80/779/EEC relating to smoke, since 1990. However, levels remain relatively high in residential areas where domestic solid fuel use is prevalent.

Ozone was monitored at four sites: three using automatic techniques (Belfast, Londonderry and Lough Navar) and one using diffusion tubes (in Fermanagh). In 2000, one of the automatic monitoring sites (at Londonderry) exceeded the target value of the latest EC Ozone Directive (2002/3/EC) and the AQS objective, on more than the permitted ten days.

Benzene and 1,3-butadiene were monitored at Belfast South until 2000, as part of a monitoring programme which concluded at the end of that year. Both pollutants were within AQS objectives in 2000.

Polycyclic aromatic hydrocarbons were monitored at two sites: Lisburn and Belfast. Annual mean benzo(a)pyrene concentrations for 2000 and 2001 were above the new AQS objective (currently applicable only to England, Scotland and Wales) of 0.25 ngm^-3. Those at Lisburn were very close to the proposed EC target value of 1.0 ngm^-3 for this PAH. Benzo(a)pyrene concentrations at Lisburn were particularly high, with annual means of 0.93 ngm^-3 in 2000, and 0.96 ngm^-3 for 2001. These values are considerably higher than those measured at most urban sites in the UK, and closer to those typically found in industrial areas than in residential suburbs. The major source of PAH is the widespread use of domestic solid fuels in this area.

The metals lead, cadmium, arsenic, nickel and mercury were monitored at three industrial sites (Campsey, Whitehead and Belfast Harbour) over a twelve-month period, December 1999 to November 2000. Annual mean concentrations of lead were well within EC and AQS limits. Annual means of cadmium, arsenic, and nickel were well within proposed EC Directive target values (which have not yet been finalised). These metallic pollutants are unlikely to constitute a serious problem in Northern Ireland.

Trends in ambient concentrations were investigated for all pollutants where sufficient years’ data were available, and in some cases significant downward trends were identified. However, by contrast, average pollutant concentrations in 2001 were, in many cases, slightly higher than those recorded in 2000. Such fluctuations are likely to be due to variations in factors such as meteorology; however they highlight the need for continued monitoring of air quality.

District Councils in Northern Ireland are currently engaged in the Local Air Quality Management Review and Assessment process. When complete, the results may highlight further areas of concern with respect to air quality. In addition, a substantial number of new automatic monitoring sites are being established throughout the region. These, too, will assist in identifying areas where action may be needed to improve air quality.