Greenpeace: poor air quality in 6 out of 10 Belgian schools.

The study "My air, my school" by Greenpeace shows that the air quality in too many primary schools is worrying or downright bad. Of the 222 Belgian schools that voluntarily participated in the study, only seven schools recorded good air quality. In 76 schools, the air that children breathe is still acceptable, but in the remaining 143 schools surveyed, the air at the school gate is unhealthy for the children. This is also confirmed by Joeri Thijs of Greenpeace. Due to the higher emission of exhaust fumes, the concentration of nitrogen dioxide is also 13 percent higher during school hours than the annual average values.

Between mid-November and mid-December 2017, four weeks in total, all participating schools measured nitrogen dioxide in the air, each at three locations: at the school gate, on the playground and in the classroom. Tubes, so-called "passive samplers", were hung at these three locations, a reliable measurement method that has already proven itself in practice in many countries. Nitrogen dioxide is an important indicator of air pollution, caused by diesel emissions in particular.

The 222 Belgian schools participated in the survey on the basis of interest, without further selection. It therefore makes little sense to make comparisons between different regions or provinces on the basis of the measurement results.

Of the participating schools, 64% come from Flanders, 17% from Brussels and 19% from Wallonia. The report does not contain individual results from the schools, but each participating school received the measurement results and personalised recommendations.

The concentration of nitrogen dioxide is expressed in micrograms per cubic metre (μg/m³). The European limit value is 40 micrograms per cubic metre, but because epidemiological studies show that there are effects on health even at lower concentrations, and because this study concerns children, Greenpeace is considering a maximum limit of 20 micrograms of nitrogen dioxide per cubic metre.

Annual average emissions of NO2

"Children are more vulnerable and much more sensitive to the negative health effects of air pollution because their bodies are still in full development," says Joeri Thijs. "Because they are smaller, they also breathe proportionally more unhealthy air than an adult person".

"Children are particularly vulnerable to air pollution"

"Children who are more likely to be in an unhealthy environment are at greater risk of asthma, allergies, lung infections and cancer, among other things. Air pollution in the classroom also leads to more learning disabilities and concentration problems".

Only seven schools have good outdoor air quality

As the European limit values for nitrogen dioxide are based on an annual average, the measurement results of November and December last year were also converted into annual average values.

In 29 schools this concentration is between 30 μg/m3 and 40 μg/m3 , which still means high exposure to poor air quality. At 101 schools a moderate air quality was measured, and at 76 schools an acceptable air quality was measured. Good outdoor air quality was measured in only seven schools.

In more than half of the schools the concentration on the playground is too high: between 20 μg/m3 and 40 μg/m3. These concentrations are too high for a playground, because playing children are more active and breathe more intensively.

The concentration of nitrogen dioxide in the classroom is often relatively low, even when the values at the school gate and on the playground are quite high. This has everything to do with the ventilation system.

More pollution during school hours

Annual mean values are of course much less representative for different times of day: in the weekend and at night the values of nitrogen dioxide in the school environment are much lower, because there is less traffic. But children are at school between about 8.30 a.m. and 4 p.m..

Based on the annual average nitrogen dioxide concentrations of 68 official measuring stations, Greenpeace has calculated the concentration of nitrogen dioxide to which children are exposed during school hours. And what turns out? During school hours the concentration is 13 percent higher.

Effect of the ventilation system

Some schools work with a mechanical ventilation system, which means "forced" ventilation. Schools without such a mechanical ventilation system ventilate in a natural way, for example by opening windows or doors.

Greenpeace has found that the concentration of nitrogen dioxide in the classroom is higher with mechanical ventilation. This effect is most visible in schools in an urban environment, where the nitrogen dioxide concentration in the outside air is already quite high. Continuous refreshing with the same polluted outside air increases the concentration of nitrogen dioxide in the classroom, even when ventilated.

"The schools are facing a dilemma here," says Joeri Thijs. "Because less ventilation doesn't always mean better air quality in the classroom. Classroom ventilation remains important to remove the carbon dioxide that is exhaled by the teacher and pupils. Too high CO2 values can lead to loss of concentration".

Countryside versus city

Of the 222 schools examined, 119 are in urban areas and 103 are in non-urban areas. In urban areas the concentration of nitrogen dioxide is significantly higher than in schools in rural areas.

The full report of the study 'My sky, my school' and also the list of participating schools can be found on the website of Greenpeace.

Source: VRT.be