Air pollution levels in Oxford plateau – new data

Published: Thursday, 20th June 2019

Air pollution levels in Oxford have plateaued, new data shows.

New data from the Oxford City Council’s 72 air pollution monitoring locations has shown that levels of toxic nitrogen dioxide (NO2) fell by an average of 0.23% between 2017 and 2018 –a starkly slower rate in comparison to the 22.7% decrease between 2016 and 2017.

Data from future years will be needed to understand whether the plateauing is a trend. A three-year plateau occurred between 2014 and 2016, before Oxford’s bus operators upgraded to cleaner Euro 6 engines – which is thought to have caused the steep reduction in Oxford air pollution between 2016 and 2017.

It is thought that another steep decline in air pollution may not occur without a further upgrade in the city’s wider vehicle fleet to cleaner technology.

Earlier this month, Oxford City Council and Oxfordshire County Council announced plans to introduce a new Low Emission Zone (LEZ) for buses, requiring all buses to be a minimum of Euro 6 standard. The new Low Emission Zone will come into force from  December 2020.

In January this year Oxford City Council and Oxfordshire County Council announced updated proposals for a Zero Emission Zone in Oxford city centre, which could be introduced in a phased approach from 2020.

Over the past decade, air pollution levels in Oxford have decreased by 36.8% due to the City Council and County Council’s work to tackle the issue.

The European Union requires national governments to keep annual average NO2 levels in towns and cities across their countries to below 40µg/m3 – a legal limit that was supposed to be met in 2010.

But health experts have warned that there is no safe level for NO2.

Although it was previously thought that emissions were responsible for around 40,000 deaths in the UK every year, new figures (European Heart Journal, March 2019) suggest it is closer to 64,000 – just 18% less than the 78,000 deaths annually caused by tobacco.

Transport is by far the most significant source of emissions of NO2 in the city, accounting for about 75% of emissions.

The new data is from Oxford City Council’s Air Quality Annual Status Report. The City Council has a legal duty to monitor air pollution in Oxford. The data provides results for each location monitored throughout 2018. (See below)

Oxford City Council monitored air quality at 72 locations across the city in 2018. Sixty nine sites were monitored using diffusion tubes and three sites using continuous monitoring equipment.

Data from the City Council’s monitoring stations indicated that the majority of air pollution increases in 2018 were between 1-2µg/m3, which is within the margin of error. The margin of error, depending on the location, is between 1-3 µg/m3.

The largest change in NO2 across Oxford between 2017 and 2018 was 4µg/m3. Only two locations saw a change of 4µg/m3 – Thames Street/Trinity Street, and New Road.

Oxford City Council also monitors air pollution at two locations that are not near roads – Oxford St Ebbes Street and Lenthall Road allotments – to measure the background level (without direct traffic impact) of air pollution in Oxford. At both these sites NO2 urban background levels rose by 1-3 µg/m3.

The increases in NO2 levels at certain sites across the city could therefore be explained by the increase in the background level. This could also mean that the increase in the urban background level is masking a larger drop in NO2 reductions in traffic.

Oxford City Council has been monitoring and reviewing air quality in Oxford since 1999. In 2010, the whole of the city of Oxford was declared as an Air Quality Management Area (AQMA) and an Air Quality Action Plan (AQAP) was adopted by the Council in 2013.

The Air Quality Annual Status Report is subject to approval by the Department for Environment, Food and Rural Affairs (DEFRA).

The impact of air pollution and cleaning up Britain’s toxic air will be discussed at a meeting in Oxford Town Hall for Clean Air Day (20/06) by Councillor Tom Hayes, Cabinet Member for a Zero Carbon Oxford, and speakers, and will be chaired by Polly Billington, Director at UK100.

Councillor Tom Hayes, Cabinet Member for Zero Carbon Oxford, said: “Oxford is now breathing the cleanest air ever. However, new figures released today confirm that we have to do more to ensure everyone in our city can breathe the cleanest air. Our 2014 Low Emission Zone has significantly reduced emissions from buses but we must do more with our Zero Emission Zone to further clean up our buses, ensure our Hackney Cabs are zero emissions capable, and restrict polluting vehicles from the city centre. Top researchers are clear that there can be no safe limit of air pollution, so, as well as increasing our efforts here in Oxford, we'll be continuing to shape Government as it writes a new air quality law. Councils like Oxford cannot allow this once-in-a-generation chance to secure more money and powers to slip through our fingers.

“We'll be discussing how we can do more in Oxford to deal with our air quality crisis on the evening of Clean Air Day, with the public, a local MP, Oxford Friends of the Earth, the director of the network of clean air cities, UK100, and the Chief Executive of Pivot Power which is investing in a new Energy Superhub in Oxford."

Polly Billington, Director of local authority clean air and energy network, UK100, said: “Air pollution is a national health crisis. UK100 is giving support to the many councils taking action, and our partnership with Oxford City Council is particularly valuable as it is develops the Zero Emission Zone and practical support for widespread adoption of electric vehicles.  People and businesses need help to switch from older polluting vehicles into cleaner ways of getting around including public transport, cycling and walking. I'm looking forward to chairing Oxford's discussion on Clean Air Day about what next needs to be done to clean up the city’s air. New clean air legislation is due and it needs include tougher, legally binding WHO air pollution limits, an independent watchdog that will hold Government to account, and additional money and powers for councils to clean up our air."

Key findings from the Air Quality Annual Status Report were:

  • Of the 72 air pollution monitoring locations, 50% showed improvements in air quality levels, 20% stayed exactly the same as the previous year, and 30% showed increases in NO2 levels.  However, the majority of the increases and decreases in air pollution levels were within the margin of error (between 1-2 µg/m3).
  • St. Clement’s Street/The Plain Roundabout had the highest annual mean for NO2 with a value of 46 µg/m3 (15% above the legal limit); however this is a 2.17% decrease on 2017 which had a measurement of 47 µg/m3.
  • For the second year in a row, all automatic monitoring sites – in St Aldate’s, High Street, and St. Ebbes – were compliant with the legal limit.
  • For the first time, BP Service Station in Woodstock Road (Wolvercote Roundabout) was compliant with legal limit, with a value of 38µg/m3. In 2017 this site was above the legal limit with 41µg/m3
  • Air pollution around the Westgate shopping centre has fallen by an average of 6µg/m3 across all 13 of the monitoring sites around the new shopping centre, when compared to levels measured in 2015 (prior to the start of construction). This new data covers the first full year of operation for Westgate Oxford.

The report found that the top five reductions in NO2 were at:

  • Pear Tree Park and Ride, where the NO2 fell by 12.0% from 28µg/m3 in 2017 to 25µg/m3 in 2018.
  • Gipsy Lane/Old Road/Warneford Lane, where the NO2 fell by 11.1% from 20µg/m3 in 2017, to 18µg/m3 in 2018.
  • Oxford Road/Between Towns Road, where the NO2 fell by 10.7% from 31µg/m3 in 2017, to 28µg/m3 in 2018.
  • Thames Street/Oxpens Road, where the NO2 fell by 8.7% from 25µg/m3 in 2017, to 23µg/m3 in 2018.
  • Bonn Square, where the NO2 fell by 8.7% from 25µg/m3 in 2017, to 23µg/m3 in 2018.


However, NO2 levels were still above the legal limit at four locations across Oxford:

  • St. Clement’s Street/The Plain Roundabout, where the NO2 was 46µg/m3 – a reduction of 2.17% from 47µg/m3 in 2017.
  • George Street, where the NO2 mean was 42µg/m3 – an increase of 4.76% (from 40µg/m3) in comparison to 2017.
  • Cutteslowe Roundabout, where the NO2 mean was 41µg/m3 – with no increase or decrease in comparison to 2017.
  • Part of the High Street, where the NO2 mean was 44µg/m3 – an increase of 4.55% (from 42µg/m3) in comparison to 2017.