- UK air standards call for average annual NO2 readings to be under 40 micrograms per cubic metre
- Dungiven breached this average several times in the 2010s
- European Environment Agency reports indicate that around 10% of sites breach this limit – meaning Dungiven isn’t unique but still has some of the worst NO2 readings in Western Europe
On 27 January, community group Glenshane Community Development Ltd tweeted:
“Why is Dungiven choked up this evening whilst the bypass lies unopened? The town has one of the worst NO2 readings in Western Europe”
UK air standards call for average annual nitrogen dioxide readings to not exceed 40 µg/m3 (micrograms per cubic metre).
Figures released by the Department for Agriculture, Environment and Rural Affairs (DAERA) show that Dungiven breached this limit several times since 2010.
Reports from the European Environment Agency indicate that this puts Dungiven in and around the top 10% of places, by levels of NO2 pollution.
Based on that, it is fair to say it has some of the worst NO2 readings in Western Europe.
What is NO2 and why does it matter?
Nitrogen dioxide (NO2) is a gas that can be produced by burning fossil fuels, most often in transport and energy generation.
Road traffic emissions are of particular concern because they raise NO2 concentrations at ground level in crowded areas where people are present.
Short-term exposure to NO2 can inflame the airways and increase susceptibility to allergies and respiratory infections. People with existing lung or heart diseases may experience worsening of their symptoms when exposed to NO2.
It can also cause changes to the environment by altering the chemistry of the soil and impact the biodiversity of vulnerable environments.
According to the UK’s Air Quality Standards Regulations 2010, the annual mean concentration of NO2 “must not exceed 40 µg/m3 and [there] should be no more than 18 exceedances of the hourly mean limit value (concentrations above 200 µg/m3) in a single year.”
The Department for Agriculture, the Environment and Rural Affairs’ (DAERA) Air Pollution in Northern Ireland 2018 reported that three sites exceeded the AQS objective for annual mean NO2 concentration (40 µg/m3), with all three located beside busy roads: Downpatrick Roadside (47 µg/m3), Belfast Stockman’s Lane (49 µg/m3), and Limavady Dungiven (51 µg/m3).
Figures from DAERA’s most recent annual report – Air Pollution in Northern Ireland 2021 – show that no sites exceeded the 40 µg/m3 limit in 2021. A reduction in traffic may be due to the pandemic.
Data capture is important for measuring air quality with accuracy. In 2021, Dungiven’s automatic analyser (which takes the readings) successfully gathered less than 75% of the intended readings (it gathered 70%). As a result, the data that was successfully recorded was “annualised to estimate the annual mean”, which required the use of data taken at Derry Rosemount and Ballymena Ballykeel for comparisons.
Dungiven’s readings for 2021 ultimately showed lower average NO2 than six other sites in Northern Ireland: 27 µg/m3, down from 51 µg/m3 in 2018.
By way of comparison, Downpatrick Roadside reduced from 47 µg/m3 in 2017 to 36 µg/m3, and Belfast Stockman’s Lane fell from 49 to 36 µg/m3.
Using DAERA’s live dashboard for air quality, it is possible to gather annual mean NO2 levels for other years, and to get a live measure of the ongoing average for this year.
The following table only uses data from years where there was a data-capture rate of at least 75%:
|Year||Annual Hourly Mean(µg/m3)||% Data Capture|
|2023 (to date)||26||99|
Figure 1 – SOURCE: Limavady Dungiven NO2 Annual statistics from Northern Ireland Air (DAERA)
To compare Dungiven’s air pollution with Europe, more generally, it is worth considering two different periods – the years just before the pandemic, and the past couple of years.
FactCheckNI asked the European Environment Agency (EEA) to provide us with comprehensive data for high-NO2 sites across Europe, but they were unable to do this.
However, the EEA does publish annual reports on European Air Quality. These do not typically include readings for individual sites but do contain useful information. Note that Dungiven’s annual average NO2 readings were 46 µg/m3 in 2017 and 51 µg/m3 in 2018.
The EEA’s Air quality in Europe – 2019 report contains information on air quality in 2017. According to the report, readings “were above the annual limit value at 10 % of all stations measuring NO2” and sites “above the annual limit value continued to be widely distributed across Europe in 2017, as in previous years.”
The report continued:
“The highest concentrations, as well as 86 % of all values above the annual limit value, were observed at traffic stations, with the exception of a few urban background stations in Turkey. In fact, the only six rural stations with concentrations above the annual limit value were traffic stations.”
An analysis of 2018’s air quality is contained within the EEA’s Air quality in Europe – 2020 report, which showed similar patterns, with 8% of all sites for which valid data was submitted breaching the annual mean NO2 reading.
This report also noted that NO2 levels have broadly been falling for over a decade – meaning that a downward trend already existed before Covid-19.
However, the pandemic has been a significant factor in reduced NO2 levels since 2020. According to the EEA: “In 2020, concentrations of nitrogen dioxide (NO2) temporarily fell as a direct result of reductions in road transport during COVID-19 lockdowns. Reductions in NO2 annual mean concentrations of up to 25% were seen in major cities in France, Italy and Spain; during the first lockdown in April 2020, NO2 concentrations monitored at traffic stations fell by up to 70%.”
The EEA’s latest data covers the years 2020 and 2021 – with only 2% of reporting stations in 2020 recording a breach of the 40 µg/m3 limit, while in 2021 (according to data still classed as preliminary) only 1% of sites recorded a breach, all of which were at roadside stations.
Asking whether Dungiven is one of the worst places in Western Europe for nitrogen dioxide pollution obviously requires comparing its NO2 readings to other places in Europe.
It is tough to make clear comparisons based on the most recent data – from 2020 onwards – both because compiling this data takes time (even readings from 2021 are still considered preliminary by the EEA) and because the pandemic created unusual circumstances, including a significant reduction in road traffic. As behaviours return to normal (or adjust into a new normal) more solid comparisons will be possible.
Concentrating on earlier data, Dungiven breached the annual NO2 average on several occasions in the 2010s.
These certainly are high readings, and this is particularly unusual among rural places – but the key factor in recording a breach seems to be traffic volume, according to EEA reports.
In 2017, EEA records showed 10% of all sites breached the annual limit. This fell to 8% in 2018. The EEA also said these breaches were fairly evenly distributed across the continent – which means these figures can be used as a reasonable representation of Western Europe, which is the area identified in the original claim.
Dungiven breached the limit on both those years. While doing so is clearly not a truly exceptional event, it does indicate that Dungiven has been in and around the top decile for NO2 pollution on a concerted basis.
In that case, it is fair to describe it as having “one of the worst NO2 readings in Western Europe.”