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Truth Behind the Headlines: Mixed pollution results for London during lockdown

King’s College London published research which presents significant reductions in air pollution from NO2, but higher levels of particulate matter in London during the lockdown period. Despite blanket coverage on the drop in air pollution in the UK media, the University has revealed results to be more mixed in London.


Its research finds that concentrations of NO2 have lowered “as much as 55% due to less road traffic”, however, “levels of PM10 and PM2.5 were in fact higher after lockdown than at any other time in 2020”. The research suggests this is due to “easterly winds, higher temperatures and pollutants from northern Europe”. Additionally, the higher temperatures post lockdown has led to higher concentrations of the pollutant, ozone.


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? Yes, “The effect of COVID-19 lockdown measures on air quality in London 2020”, published May 2020.
2. Who is behind the study it refers to? Kings College London - a reputable London University which ranks 36th in the World University Rankings.
3. How fantastical and radical is the claim that is being made? The research presents robust results regarding mixed levels of pollutants during lockdown. However, as the research states, it is a preliminary assessment and a considerable amount of further work could be done using the large amount of data collected by King’s College London.
4. What geographical region does the claim refer to? London, England
5. What is the sample size of the study?

The samples were taken from 50 sites across London (out of 100 sites from London Air Quality Network sites which monitor pollution levels on an ongoing basis). These sites are located in roadside, suburban and urban background (locations such as residential and commercial areas of cities that are away from direct sources of emissions) areas. The sample excludes industrial sites.


This sample size is a large specific city but, as the report states, a more comprehensive analysis for the specific lockdown period, combining changes to European, UK and London emissions as well as a wide range of population subgroups could be undertaken as part of a larger study.

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