Recommendations made following new research into London classrooms

New research by the University of Surrey’s Global Centre for Clean Air Research (GCARE) has established that classrooms using dual ventilation systems can cut harmful air pollution in half compared to those that use normal ventilation.

The research looked at CO₂ and PM concentrations in 30 classrooms across five London schools during the winter (January–March 2022).  

It also examined the influence of ventilation, volume of classroom, floor location, floor type and occupancy on CO₂ and PM concentrations, together with air temperature and relative humidity.

Out of 30 monitored classrooms, 80% had natural ventilation (door, window and skylight openings), 13% had mechanical ventilation, and 7% had a combination of both systems (dual ventilation). 

The study found that when the classrooms were occupied, the levels of PM10, PM2.5, and PM1 were 230%, 125%, and 120% higher, respectively than when they were empty.

It was also seen that when dual ventilation systems were used, the concentration of PM10 was reduced by approximately 50% compared to natural ventilation methods.  

The study also noted that classrooms with wooden and vinyl floors had higher levels of PM10 compared to those with carpeted floors but it was speculated that this might be due to particle resuspension from wooden and vinyl floors, whereas carpets act as a sink for PM and can trap dust and allergens.

Additionally, classrooms located on the ground floor had a greater ratio of PM2.5 to PM10 than the upper floors, indicating that outdoor PM2.5 particles were entering the classroom.

The study concluded with recommendations for schools to consider, such as installing real-time pollution monitoring equipment and dual ventilation systems.

Professor Prashant Kumar, Co-Director at the University of Surrey’s Institute for Sustainability and Founding Director of GCARE, said: ‘Indoor air quality has a substantial effect on human health, wellbeing and performance, specifically in children, who are more vulnerable and sensitive to the presence of indoor air pollutants.  

‘Our research across London schools shows a need for more support into how particulate matter is banished from classrooms as high occupancy meant 150% more CO2 and 230% more harmful particles floating around. 

‘The CO2 levels didn’t vary much based on the different floor levels and types. However, classrooms bigger than 300m³ naturally had higher ventilation rates.’ 

Professor Paul Linden from the University of Cambridge said: ‘We encourage teachers, pupils and parents to work with our Tackling Air Pollution At School (TAPAS) network to establish good practice and adequate ventilation to reduce classroom pollution.’

Information about TAPAS and how you can participate can be found on their website.