A recent study commissioned by the Greater London Authority (GLA) and delivered by WSP has confirmed the value of air filtration in schools. The pilot tested a range of air purifiers across five London primary schools to see how well they reduced fine particulate matter (PM2.5) and how practical they were for everyday classroom use.
The results were clear. Every commercial system improved classroom air quality, giving staff and pupils cleaner, healthier air throughout the day.
The Blast: strong results, quiet presence
The largest unit tested, the Blast, achieved the strongest results. At one school, PM2.5 levels fell by 68.4% compared with the control classroom. Even in areas with lower pollution, the Blast still reduced PM2.5 by around 2 micrograms per cubic metre during the school day.
Teachers said it ran quietly, blended into the background and didnโt interfere with lessons. It proved to be a practical choice for daily use in busy classrooms.
Comparing the options
| Filter type | Maximum PM2.5 reduction | Typical reduction | Notes |
|---|---|---|---|
| Blast (large unit) | Up to 68.4% | 30โ60% | Quiet, effective, well received |
| Medium commercial unit | Up to 50.8% | 20โ40% | Reliable but a little noisier at higher settings |
| Small commercial unit | Limited testing | โ | Compact and useful for smaller rooms |
| DIY filter | 0โ8% | โ | Bulky, noisy and removed from some schools |
Medium units also performed well but were more affected by room size and layout. The smaller models were suited to compact classrooms but were not part of the full monitoring programme. DIY filters, made from box fans and basic filters, proved unpopular and were often removed due to safety or noise concerns.
Whatโs next
Following the success of the pilot, the Mayor launched a ยฃ2.7 million School Filters Programme that will bring air filters to 200 London schools. Smart Air units were selected, with the Blast for larger classrooms and the Blast Mini for smaller spaces.
The Blast Mini has also received top marks from the independent review site HouseFresh, which praised its fast and efficient performance.
This rollout marks an important step towards cleaner, healthier learning environments across London. Clean air is no longer a luxury. Itโs a practical solution and a blueprint to rollout across the UK.
