Children in London schools are being exposed to higher levels of damaging air pollution inside the classroom than outside, putting them at risk of lifelong health problems, a new study has revealed.

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Scientists studied five primary schools and one nursery in the capital as part of research into levels of air pollution indoors. The research shows that outdoor air pollution from diesel vehicles and other sources – both of nitrogen dioxide and particulate pollution – is affecting the lives of children inside schools.

Young children – who are more vulnerable to airborne pollutants than adults – are breathing in fine particle pollution (PM10 and the even smaller PM2.5) at levels which are higher than the annual World Health Organisation guidelines of 20μg/m3 and 10μg/m3 respectively, the report said. Particulate pollution is primarily a product of diesel vehicles, tyre and brake dust, and solid fuel-burning, but can also come from inside a building itself.

In the case of PM10, children are being exposed to higher levels inside their lessons than outside on the street or in the playground, the report found.



The study, which was commissioned by the mayor of London and carried out by the Institute for Environmental Design and Engineering at University College London and the University of Cambridge chemistry department, examined five primaries and one nursery.

The report said a significant level of air pollution indoors in urban areas was due to outdoor pollution penetrating the buildings.

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“Children living or attending schools nearer high-traffic density roads were exposed to higher levels of motor vehicle exhaust gases and had higher incidence and prevalence of childhood asthma and wheeze,” it said. “A higher incidence of childhood asthma was positively associated with exposure to nitrogen dioxide. Exposure to particulate matter was also associated with a higher incidence of wheeze in children.”

The study does not call for classrooms to be sealed off from outside air pollution as the issue is complex, and some studies indicate cognitive performance of children in classrooms is improved at lower temperatures with more ventilation.

The schools studied were a modern suburban nursery and primary school away from high traffic streets, a Victorian-built primary next to a busy road, two similar schools away from high traffic areas and a suburban modern school building close to a major road.

The findings came as the mayor published his first audit of air pollution at 50 of the capital’s schools and a series of measures to help them counter the impact of poor air quality around their schools.

The mayor on Thursday announced the creation of a £1m fund to help the worst-affected schools bring in changes immediately. The money will also provide 20 nurseries with air quality audits and indoor air filters.

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A spokesperson for the mayor said: “This report shows that indoor air pollution is a serious problem in our city’s schools, but the problem will not be resolved by simply opening or closing windows and doors. Instead, we need to reduce sources of air pollution in and near schools.”

The research highlights just how at-risk children are to the impacts of dirty air. “Children spend a great deal of time inside school buildings,” the report said. “They are more vulnerable to airborne pollutants than adults not only because of their narrower airways, but also because they generally breathe more air per kilogram of body weight.



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“The exposure of children’s developing lungs to air pollution can result in reduced lung function that persists through to adulthood, increasing susceptibility to respiratory and cardiovascular disease.”

The British Lung Foundation welcomed the Mayor’s fund for the worst polluted schools but said it was now up to the government to take action. Alison Cook, director of policy at the foundation, said: “We know that air pollution can stunt the growth of children’s lungs, and is linked to asthma and chronic chest problems later in life. Nothing is more precious than our children’s health, and we’re pleased to see that cleaning up the toxic air around schools is a priority for the mayor of London.

“But more must be done. The government must match this commitment by taking action to protect all of our lung health, including new and safer legal limits for air pollution.”

Recent research suggests that even low levels of PM2.5 pollution can cause heart problems, and experts have said it is an urgent public health priority and suggestedtargeting the worst offenders, such as diesel vehicles, with policy measures.

The new research was published in the week the environment secretary, Michael Gove, was criticised for not taking tougher measures against diesel vehicles in his air quality plan. The government’s failure to act on air pollution from diesel vehicles was this week referred to Europe’s highest court.

• This article was amended on 29 May 2018 because the annual World Health Organisation guidelines for the levels of fine particle pollutants PM10 and PM2.5 are 20μg/m3 and 10μg/m3 respectively, not 10μg/m3 and 20μg/m3 as an earlier version said.