Use Case: Education

The short answer

For a class of up to 32 people — pupils and staff — the Department for Education’s specification asks for an air cleaning unit delivering at least 720 m³/h of clean air at its working setting, within a noise limit. Air cleaning units remove airborne particles but do not lower CO₂ or replace ventilation, so windows, vents and CO₂ monitoring come first. Ask HATL which model and setting suits your room size and class.

What the DfE says (England)

• DfE ventilation guidance (24 February 2026): consider air cleaning units where you cannot maintain adequate fresh air until remedial work is done, or where outdoor pollution is a concern. CO₂ over 1,500 ppm means ventilation is poor.
• The DfE recommends HEPA units only and does not recommend air ionisers, ozone generators or open UV. The negative-ion function on HATL units can be switched off; we recommend running with it off in schools.
• The DfE air cleaning unit specification sets clean-air rates by the number of occupants, including staff. Noise limits apply at the setting that delivers that rate, and where several units are used, to their combined sound. The specification also covers floor-standing equipment, certified filtration, a 4 m power lead, a timer and a filter-change warning.

HATL can supply a 4 m power lead on request. Ask us for working-setting CADR and noise data for the model you are considering before checking it against the specification.

How many units, by room size?

Ceiling height 2.7 m. Clean air added by each unit at maximum setting. Portable units shown, as the DfE specification covers floor-standing equipment.

The table shows the clean air the purifier adds at its maximum setting. Existing ventilation also counts towards the total. At quieter settings each unit delivers less clean air than shown. Final selection depends on occupancy, ventilation, room layout, noise and the requirements of the setting. In a classroom, the DfE occupancy rate and noise limit at the working setting also apply.

Running cost

At maximum setting for 8 hours a day over 190 school days (1,520 hours a year), at 26.32p/kWh excluding VAT, electricity costs approximately £18 a year for each HA500 and £32 for each HA800. A classroom using two units costs twice as much. Running at a lower setting costs less but delivers less clean air.

Filters: £150 (HA500) or £240 (HA800) per replacement set of two filters, including VAT, typically lasting about two years in UK use — roughly £75 or £120 a year per unit.

What the evidence shows

• HATL classroom monitoring: in a primary-school classroom in Ondřejov, Czech Republic (21 November–19 December 2025, 2,632 readings), PM2.5 and PM10 stayed consistently low while Healthy Air units were in use — averaging 4.7 and 4.8 µg/m³, with PM2.5 above 15 µg/m³ in only 6 readings. CO₂ still rose above 1,000 ppm during lessons, so ventilation remained necessary. The monitoring had no untreated comparison room and no outdoor readings, so it is not a controlled trial.
• A Southwark Council study of three schools and three care homes (Urban 360, 11 months) found air purifiers cut PM2.5 by an average of 18% in classrooms during school time — less than in care homes, because pupils move between rooms and doors open (Southwark Council, 2024). Its advice: leave purifiers running continuously.
• University of Surrey research in three London primary schools (2022) found classroom air purifiers reduced particle concentrations by up to 57%.
• The Southwark and Surrey studies did not test HATL products. HATL’s laboratory results should not be read as classroom performance.

FAQs

Do air purifiers reduce CO₂ in classrooms?

No. They remove particles; only fresh air lowers CO₂. Keep using CO₂ monitors and ventilation.

What size air purifier does a 30-pupil classroom need?

Count everyone in the room: 30 pupils and 2 staff is 32 occupants. The DfE specification asks for at least 720 m³/h of clean air at the unit’s working setting, within a 49 dB (LWA) noise limit. Ask HATL which model and setting meets this for your room.

Are ionisers allowed in schools?

The DfE does not recommend air ionisers. The negative-ion function on HATL units can be switched off, and we recommend using them with it off in schools.

Sources

• Department for Education — Ventilation and air quality in education and childcare settings
• Department for Education — Air cleaning unit specification
• Lancet COVID-19 Commission — Proposed Non-infectious Air Delivery Rates (Nov 2022)
• Southwark Council — Real-world research on air purifiers in schools and care homes (2024)
• University of Surrey — Air pollution measures in London schools (2022)
• Ofgem — Energy price cap, 1 October to 31 December 2026
• HATL — Evidence & Test Results