Levels of the harmful carcinogen benzo[a]pyrene (BaP) continue to be a problem in Northern Ireland, with all sites that monitor the pollutant reporting breaches of the UK limit in 2013.
BaP is one of 17 polycyclic aromatic hydrocarbons (PAHs), and the Department for the Environment in Northern Ireland (DOENI) believes that high PAH concentrations are “likely due to widespread residential combustion of smoky (bituminous) coal”.The pollutant has been measured at five different sites in NI since 2001 and is closely linked to causing some forms of cancer, according to DOENI’s Environmental Statistics Report published last week (February 26 2015).
The report compared the current BaP concentrations in NI – measured in predominantly residential areas – to similar concentrations shown in industrial areas elsewhere in the UK, such as Scunthorpe, Middlesbrough and Port Talbot.
However, while the NI sites have failed to show compliance for BaP with the UK annual average objective of 0.25 ugm3 (microgrammes per cubic metre), they are, on the other hand, all in compliance with the less stringent EU annual mean target value of 1 ugm3.
There are a total of 23 monitoring stations in NI tracking data on the likes of carbon monoxide, nitrogen oxides, sulphur dioxide, particles, ozone, benzene and PAHs, and the annual statistics report also looks at levels of these pollutants in 2013.
With regards to nitrogen dioxide, levels have remained “relatively stable” over the last 13 years at the 20 sites which monitor the pollutant, varying between 19 ugm3 and 27 ugm3. According to the report, background levels of NO2 have not shown a clear trend or decrease because emissions from road vehicles “are still a problem”.
Roadside levels have seen more variation, though, with the average across sites ranging from 26 ugm3 and 45 ugm3 in 2013, thus showing some exceedances of the UK and EU limit for average annual limit of 40 ugm3.
However, none of these sites breaching NO2 limits are used to assess UK compliance with the EU Air Quality Directive – although one site which “occasionally” breaches the annual average NO2 limits was added to the list of UK sites used for reporting to the European Commission.
Elsewhere, the report shows that all sites in NI met the 40 ugm3 annual average limit value for particulate matter PM10 in 2013, as well as a continuing slight decline in ammonia concentrations, which are largely from agricultural sources.
And while ozone levels – which are monitored in Belfast, Lough Navar and Londonderry – “do not appear to be decreasing”, no sites exceeded the UK and EU objective of 120 ugm3 on more than 25 days a year.
There has also been a “marked reduction” in sulphur dioxide (SO2) in recent years – one third less in 2013 compared to 2010 – which the report links to the introduction in NI of mains gas as a heating fuel, thereby reducing the use of oil and solid fuel (coal) in the industrial and commercial sectors.
Indeed, 2013 marks a decade since the last exceedance of any SO2 limit value in NI.
The report also cites the results of NISRA’s continuous household survey for 2013/14 found that 26% of respondents listed traffic congestion and 19% listed ‘traffic exhaust fumes and urban smog’ within their top three environmental problems that were most important to them.
The problems most commonly listed by respondents as the most important were illegal dumping of waste (42%) and pollution in rivers (30%).