One in four of London’s green spaces breaches air quality safety limits

More than one quarter of London’s parks, playground, and open spaces exceed international safety limits for air quality, potentially putting thousands of children and vulnerable Londoners at risk.

In an analysis of the annual air quality levels in green spaces across the capital’s 33 boroughs, researchers from Imperial College London and the University of Leicester used nitrogen dioxide (NO2) estimates, comparing them against safety limits set by the European Union and World Health Organisation.

They found that 24% of play spaces and 27% of public parks had NO2 limits exceeding safety standards, with 67% of private parks failing to keep within safe levels. The closest play space for 250,000 children under the age of 16 (14% of the city’s children) had NO2 concentration averages exceeding European Union limits, with the majority of children affected living in the most deprived areas of the city.

Professor John Gulliver, University of Leicester Deputy Director of the Centre for Environmental Health and Sustainability (CEHS), said: “This study used sophisticated computer modelling to produce the air pollution map, commissioned by the Mayor of London. The majority of parks and playgrounds where NO2 concentrations exceeded the safe limit set by the World Health Organisation (annual average of 40 micrograms/m3) were in Central London, which is worrying for anyone living in or visiting the heart of the city."

In response to the findings, the team is launching an interactive website which lets people check their local green spaces to get information about average annual NO2 levels.

The findings, published recently in the International Journal of Environmental Research and Public Health, used data (breaking London into a grid of 20 metres squares) from the London Atmospheric Emissions Inventory (LAEI), developed by King’s College London.

Using data from 2016, the latest estimates available, the Imperial team applied measures from the closest grid squares to green spaces to give an NO2 average for the year for 4,470 parks, gardens and open spaces. Census data from 2011 provided information on number of children under the age of 16 in close proximity to green spaces.

Green spaces included public parks, private parks (including Kew Gardens and Buckingham Palace Gardens), allotments, cemeteries, playing fields, golf courses, tennis courts and other sports areas, and other play spaces including playgrounds.

The European Union safe limit for NO2, in accordance with the World Health Organisation, is set at an average of 40 µg/m3 per year.

The highest average annual levels of NO2 in green spaces were found in inner London boroughs, with City of London, Westminster, Camden, Kensington and Chelsea and Islington having the highest levels of all London boroughs. Five of the 10 most polluted parks in London were found in Westminster, and the worst air quality was found to be Victoria Embankment Gardens (annual average NO2 59.7 µg/m3) and Parliament Square Gardens (58.7 µg/m3).

According to the researchers the findings offer more insights into the exposure of children to air pollutants, as well as highlighting variations in exposure linked to social deprivation. The average NO2 levels for open spaces in the most deprived areas were 6 µg/m3 higher than the average for the least deprived areas. The authors highlight in their study that the concentrations of NO2 steeply declines with distance from source, so levels in the centre of a large park are likely to be far lower than at the edge, close to a road.

Nitrogen dioxide is a pollutant which in London is predominately emitted from vehicles, but also wood-burning stoves, and other domestic, commercial and industrial sources. Prolonged exposure to high levels of NO2 can damage the lungs and in children is linked to conditions such as asthma, reduced lung growth and even reduced brain function. Previous studies estimated the effects of high levels of background NO2 in the environment as being as bad for children’s lungs as maternal smoking.

The researchers will unveil an online platform that allows people to explore air pollution levels in their local parks and playgrounds at an event hosted at Imperial this week.

The work was supported by funding from the Medical Research Council as part of the MRC Centre for Environment & Health, as well as the Academy of Medical Sciences/Wellcome Trust Springboard Health of the Public Award [HOP001\1001].