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Air pollution: nitrogen dioxide (NO2) concentrations
Exhaust emissions from road traffic are, in general, detrimental to local air quality with there being a direct link between traffic levels and the amount of air pollution. National air quality regulations require local authorities to monitor local air quality, including NO2 concentrations. The Air Quality Regulations 2000 set the objective of 40 micrograms per cubic meter (µg/m3) or less, when expressed as an annual mean. This data is monitored, at 56 sites throughout Herefordshire (including duplicate measurements at some site locations), by Herefordshire Council's Environment Directorate.
Table 1: Average annual NO2 concentrations (µg/m3) for Herefordshire market towns 2004-2007
Source: Environment Directorate, Herefordshire Council 2008
Figures for Herefordshire (table 1) show that, in 2007, Victoria St. and Edgar St. in Hereford and Bengry's lights in Leominster all exceeded the 2005 objective of 40 µg/m3 and have done so for the previous three years. All three have increased over the period 2004 to 2007, but the two Hereford sites decreased between 2006 and 2007. Despite this they remain high above the objective value. All other market town sites remained below the objective for the four-year period.
Chart 1. Annual mean levels of nitrogen dioxide NO2 (µg/m3)
Source: Environment Directorate, Herefordshire Council 2008
Out of all the sites 25 out of 56 were over the 2005 objective level of 40 µg/m3. When looking at changes since 2004, only 13 out of 43 sites showed a reduction in NO2 concentrations. Out of the market town sites only 2 out 7 showed a reduction in NO2 concentrations. Victoria St. in Hereford showed the greatest increase (19.4%) followed by Kington (15.5%) and the site at Bengry's lights in Leominster (12.7%). Ledbury Town Centre showed the greatest reduction (13.6%).
For more information on air quality please see the Air Quality page on the Herefordshire Council website.
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