Teachers, leave them windows open
Windows in New Zealand primary schools should be opened more often to combat air pollution, a new study has found.
‘‘There is a need … to reduce exposure to indoor air pollution at schools,’’ reported lead author Dr Julie Bennett.
She and colleagues tested the indoor and outdoor air quality at an unnamed Wellington primary school in October 2016. It was a classic classroom from the 1970s – a one-storey, prefabricated, weatherboard building probably designed to be temporary but still going.
The single classroom tested was not insulated, the roof was corrugated steel and the floor carpeted. Heat came from an electric fan heater and ventilation was supposedly provided by open windows on both sides. A busy road passed the school gates.
But the windows weren’t opened enough and various types of air pollution built up over the day.
The researchers measured the levels and sources of carbon dioxide, nitrogen dioxide, particulate matters 2.5 and 10, temperature, humidity and other factors.
They found that indoor PM10 levels were ‘‘significantly … higher’’ than outdoor concentrations. Analysis found the PM10 probably came from soil brought into the school room on shoes.
PM2.5 levels were also found to be significantly higher indoors than out. PM2.5 was thought to come from the exhausts of passing vehicles.
PM10 is particulate matter 10 micrometers or less in diameter, while PM2.5 is particulate matter 2.5 micrometers or less in diameter and often described as ‘‘fine particles’’, according to the Australian National Pollutant Inventory. About 40 fine particles could be placed on the width of a human hair.
These tiny particles are drawn deep into the lungs and sometimes into the blood.
‘‘Poor indoor air quality impacts students’ cognitive function and development, comfort, concentration and performance,’’ wrote Bennett, a research fellow at the Department of Public Health at the University of Otago, Wellington campus.
Bennett and colleagues cited international studies showing primary school children exposed to high levels of traffic-related air pollution had slower cognitive development than children attending lower polluted schools. A recent study from Barcelona found primary children exposed to air pollution while at school had increased behavioural problems.
A study of air quality in 51 Portuguese schools reported high levels of carbon dioxide impacted cognitive function and therefore learning.
Respiratory and cardiovascular systems were also affected, especially in children.
Asthma, a respiratory condition, causes hospitalisation and school absenteeism. The link between air pollution and cardiovascular health got less attention in the research literature but ‘‘may be as significant as on lung health’’, Bennett and her seven coauthors reported in the journal Atmospheric Pollution Research.
Bennett’s team also found elevated levels of carbon dioxide in the classroom. This almost certainly came from children and teachers breathing.
Many of these problems could be addressed if windows were opened more often, especially to create cross ventilation. Several international studies have shown that high ventilation rates in classrooms improve children’s health and school attendance. Bennett wrote that about 90 per cent of New Zealand classrooms are designed to be ventilated by windows.
Many new classrooms and some refurbished ones have systems that automatically open windows or skylights for ventilation.
Schools should also drop carpets, as they collect dust and are harder to clean than hard floors, Bennett said in an interview. Although a case study of a single classroom, Bennett expected ‘‘most schools would have similar results to this’’.