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Brussels/London, 18 June 2019 – The air quality inside – as well as outside – primary schools across Europe must be improved to protect children’s health and ensure optimal learning, finds a new Health & Environment Alliance (HEAL) study entitled “Healthy Air, Healthier Children”. The data for London is built on a citizen science monitoring initiative that measured indoor and outdoor air pollutants at seven schools in Lambeth, which is one of the most polluted boroughs in London[1]. It shows the presence of nitrogen dioxide (NO2) inside and outside all classrooms, highlighting the urgent need to further tackle traffic pollution. The monitoring also found high levels of carbon dioxide (CO2) inside classrooms, indicating the need for better ventilation.

Jonathan Grigg, Professor of Paediatric Respiratory and Environmental Medicine at Queen Mary University, said: “This report highlights that exposure of children to toxic compounds in the air not only occurs outdoors – but also in schools. More research is therefore urgently needed on the health effects of these exposures, and health-based indoor exposure limits must be developed for school children.”

Air pollution is the number one environmental threat to health in Europe and globally, leading to 400,000 premature deaths and hundreds of billions of euros in health costs in the EU[2] each year[3]. In the UK alone, around 40,000 deaths are attributable to exposure to air pollution[4]. Evidence demonstrates that children are particularly at risk from polluted air, which can increase the risk of a child developing asthma and lead to an increase in the number and severity of asthma attacks, especially if a child lives close to a busy road. Indeed, the UK has the highest prevalence of childhood asthma across Europe[5]. Air pollution can also impact a child’s heart, brain and nervous system development, even before birth.

The World Health Organization (WHO) states that no level of air pollution can be considered safe[6]. It is already known that London exceeds EU NO2 air quality standards, with half of emissions coming from road traffic[7]. For the HEAL citizen science monitoring project, particulate matter (PM), nitrogen dioxide (NO2) and carbon dioxide (CO2) were monitored during March-April 2019, with the active participation of schools and children and HEAL’s partner organisation Sustrans. The initiative was also rolled out in five more European capitals – Warsaw, Berlin, Paris, Madrid and Sofia – totalling 50 schools.

In London, outdoor NO2 (a pollutant coming predominantly from traffic, especially diesel-powered vehicles[8]), measured at the school entrances for one month, came close to the annual EU legal limit and WHO guideline of 40µg/m3, with averages of 35µg/m3 and 36µg/m3 NO2 at two schools. These levels are averages, however, and are likely to have been higher during school hours, particularly drop off and pick up times, due to higher traffic volumes compared to evenings and weekends. The project also found NO2 inside each of the seven classrooms ranging from an average of 12 µg/m3 up to 26 µg/m3. As there are no indoor sources of NO2, this pollutant is travelling in from outside.

Yvonne Morris from Hitherfield Primary School, one of the seven schools that actively participated in the project, said: “We take air quality very seriously in our school, as we want to provide the best environment we can for our children inside and outside the school. It was very interesting to monitor the pollution, particularly inside the school. Before we started the project, we didn’t really know much about nitrogen dioxide, the fact it might travel into the buildings and how harmful that could be.”

Keeping windows and doors closed to prevent pollution from entering is not a solution, as there is a need to air out classrooms, especially to decrease CO2 levels. A previous study expressed the need to limit CO2 to 1,000ppm to prevent a negative impact on academic performance, as higher concentrations can contribute to headaches, dizziness and the inability to concentrate. The HEAL study found levels of between 1,195ppm and 2,750ppm in London classrooms.

Xavier Brice, CEO at Sustrans, the UK walking and cycling charity that carried out the air quality monitoring around the seven schools in London, said: “This report contributes to the mounting evidence that air pollution is a real threat to our health and wellbeing, and in particular to our children’s. Until we end our reliance on motor vehicles for local journeys, the plague of pollution over our streets and inside schools will continue. The UK government needs to show leadership by making it easier for local authorities to close streets outside schools to motor vehicles during drop off and pick up times, and deliver a network of walking and cycling routes to school so that every child is able to travel by foot, cycle or scooter in safety and with confidence. The failure to resolve this denies our children their basic human right – to breathe clean air.”

Jemima Hartshorn, Founder of Mums for Lungs, a network of parents campaigning for clean air, said: “We are really supportive of this project. Lambeth is one of the most polluted boroughs in the UK and the air quality is having a negative impact on children’s health. By measuring the levels of air pollution in schools, where children spend so much time, this project will raise real awareness amongst pupils, parents and policymakers about the urgent need for action – and will allow stakeholders to ensure that the best and most pollution-reducing action is implemented.”

The report includes recommendations for policy-makers, but also for school authorities, parents and the health sector. These focus on the need for comprehensive, long-term monitoring, but also a range of measures that will clean up the air outside, so pollution does not travel inside the classrooms.

Anne Stauffer, Director for Strategy and Campaigns at HEAL, said: “HEAL’s snapshot investigation underlines the need for policy, teacher and parent action on clean air in schools. This should start with policy-makers prioritising healthy schools where children can breathe healthy air. It is unacceptable that the cities in our investigation, and many more in the EU, exceed the EU’s air quality standards. In cities, emissions from cars, buses and lorries are a major contributor to poor air quality, so investments should be made into not only reducing traffic around schools, for example with a ban on engine idling or restricted school streets, but also to finance those measures that will lead to a decrease in car use overall.”

Read the full report here



Elke Zander, Health and Environment Alliance (HEAL),, tel.: +32 (0)2 234 36 47










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