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Truth Behind the Headlines: Diesel car pollution is significantly higher in London suburbs than in central London

The media recently reported that a study of air pollutants in London has shown that nitrogen oxide (NOx) levels from vehicles are much higher in neighbourhoods outside of the capital’s centre. This includes nitrogen dioxide (NO2) which has been proven to have many adverse health impacts such as causing respiratory complaints and worsening existing heart and lung diseases.


It was reported that nitrogen oxides (NOx) from diesel vehicles were on average 23% higher at locations outside of central London’s Ultra Low Emission Zone (ULEZ). Furthermore, many of the sites where diesel cars were identified as contributing the most to NOx pollution, will also be outside of the extended ULEZ zone which starts in April 2021.


One of the areas with the highest pollution concentrations was also one of London’s most deprived neighbourhoods and which has high incidences of very poor respiratory health. For example, it was highlighted that the proportion of young people (aged between 10 and18 years) that required emergency admission for asthma was 57% higher in that area than across England as a whole. 

Using our recommended five tips, Global Action Plan reviewed the study:


Questions to ask to get to the truth Our response
1. Does the article refer to a report to back up its claims? The article refers to the modelling of reputable data from air pollution monitoring sites across London, which has been analysed and reported online but not in an academic journal, so it has not been officially peer reviewed.
2. Who is behind the study it refers to? Environmental Defense Fund Europe (EDF) - the organisation that runs ‘Breathe London’, a network of air quality monitors that operate across London. They use the data recorded to produce maps to help inform the general public about their local air pollution. The organisation then uses data analytics to better understand localised air pollution exposure.
3. How fantastical and radical is the claim that is being made?

The claim was made after carrying out modelling of recorded data which means that it has an evidence-base. The researchers also explained their methodology and gave the sources of additional information they used, which is good practice.

The introduction of the ULEZ has previously been shown to have decreased traffic related air pollution within central London and this supports the proposal that NOx levels inside the ULEZ may now be lower than areas outside of the zone. Moreover, the Royal College of Physicians Special Advisor on air quality and UKRI Clean Air Champion at the University of Southampton said that the study results provide further evidence for the need to remove diesel cars from our roads; indicating a belief in the results thereby giving more credence to the study.

4. What geographical region does the claim refer to? London
5. What is the sample size of the study?

The researchers used data from 231 monitoring sites across London for the modelling. They employed independent research team to estimate the average source-specific hourly NOx concentrations (µg/m3) from 1st April 2019 to 12th December 2019.

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