Schools and air pollution in London

Last week Sadiq Khan revealed plans to install air filters in 200 London schools, stating:

“I want every single child to breathe clean air in and around their school”

This is certainly a worthwhile goal.

The evidence on the impact of air pollution on physical heath is well established. For instance, in 2019, pollution has been estimated to be responsible for the equivalent of between 3,600 to 4,100 deaths in Greater London.¹

The evidence on the effects of pollution on education related outcomes are however mixed. Traffic-related air pollution, specifically NO₂, has been shown to be associated with lower educational attainment at age 15/16, but the same is not true for other pollutants.² Similarly, there is mixed evidence on the association between exposure to different air pollutants and cognitive development up to age 7.³ Pollution does not appear to be associated with school attendance on average across all schools, but reducing pollution does appear to increase attendance at schools with a high share of disadvantaged students.⁴

Regardless of the precise effects during childhood, early childhood exposure to pollution has been shown to have significantly impacts on later life outcomes.⁵

In this blog I link data on pollution, specifically annual average concentrations of Nitrogen Dioxide (NO₂) and particulate matter (PM₁₀ and PM_2.5) with schools in London.

These are some of the most commonly measured air pollutants. NO₂ is a gas that is mainly produced during the combustion of fossil fuels and linked to respiratory issues. Particulate matter (PM) is everything in the air that is not a gas and therefore consists of a huge variety of chemical compounds and materials. Due to the small size of many of these particles they are able to enter the bloodstream.

I reveal 4 key facts which illustrate the extent of the pollution problem surrounding the capital’s schools, and in particular highlight the link between pollution and school level deprivation.

1) Pollution concentrations in London are high, but varied

These maps show DEFRA’s modelled annual mean average concentrations of pollutants in 1×1 km grid cells. The most polluted areas are shown in green/yellow. There is visible variation across the capital, and the maps highlight particularly high concentrations in the city centre and around major roads such as the A406 and M25. The area around Heathrow airport is also clearly highlighted as having high concentrations of NO₂.

Source: Defra via uk-air.defra.gov.uk and ONS

2) Almost all schools are located in areas that have annual average concentrations of pollutants in excess of WHO guidelines

The WHO’s air quality guidelines state that annual average concentrations of NO₂, PM₁₀ and PM_2.5 should not exceed 10, 15 and 5 μg/m³ respectively. All schools in London are located in areas with average annual concentrations of NO₂ and PM_2.5 above these WHO guidelines. In addition, 86.4% of schools are in areas with average annual concentrations of PM₁₀ above the 15 μg/m³ WHO guideline.

3) There is an association between school level deprivation and the concentrations of pollution in the local area

For instance, a 10 percentage point higher rate of FSM eligibility in a London secondary school is associated with a 1.57 μg/m³ higher annual average concentration of NO₂, and 0.75 μg/m³ and 0.27 μg/m³ higher concentrations of PM₁₀ and PM_2.5.

4) There is variance in pupils’ exposure to pollutants by London borough

Pupils attending schools in south and east London boroughs (such as Bromley, Havering, Sutton, Croydon, and Bexley) have some of the lowest average annual exposures to pollutants, whist those attending school in central London boroughs (such as City of London, Islington, Tower Hamlets, Westminster and Hackney) experience the highest levels of exposure.

Conclusion

The Mayor’s announcement last week to pilot air filters in schools is welcome. He is right to take the issue of pollution seriously given we know that childhood exposure to high concentrations of pollution can have detrimental impacts on later life outcomes. All schools in London are affected by high levels of pollution but those in Inner London, near major infrastructure and notably, in more deprived areas are particularly affected. Therefore, these factors must be taken into consideration when deciding which schools to choose for the air filter pilot and any potential future roll out.

Data acknowledgements

© Crown copyright 2021 Defra via uk-air.defra.gov.uk, licensed under the Open Government Licence

Office for National Statistics licensed under the Open Government Licence v.3.0

Contains OS data © Crown copyright and database right 2024

Footnotes

1. Dajnak (2021)↩︎
2. Mizen et al. (2020)↩︎
3. Milojevic et al. (2021)↩︎
4. Keivabu and Rüttenauer (2022)↩︎
5. Currie et al. (2013)↩︎