Air Purifier for Haze in Singapore: CADR & Room Sizing
To size an air purifier for Singapore haze, start with room volume and smoke CADR. A square-metre claim alone does not tell you how quickly a purifier delivers cleaned air, and a generic CADR figure is not automatically the smoke CADR used in NEA's haze guidance.
This guide explains the calculation with the APEX+ Aero's published 300m³/h CADR. The calculation is transparent, but it is not a certification that the Aero's number is AHAM smoke CADR.
What NEA says about portable air purifiers during haze
Singapore's National Environment Agency says portable air purifiers can further reduce indoor particulate matter. Its guidance recommends an efficient filter such as HEPA and says smoke CADR is the most appropriate CADR reference for haze pollutants.
For a room measured in cubic metres, the guide recommends smoke CADR of at least three times the room volume. It also warns that open doors and windows, room leakage, placement and airflow obstruction affect real performance.
Read NEA's indoor-haze guidance.
Step 1: calculate room volume
Room volume in m³ = length in metres × width in metres × ceiling height in metres.
A 4m × 3m bedroom with a 2.6m ceiling contains 31.2m³. Include a connected hallway or study if the door normally remains open while the purifier runs.
Step 2: calculate the haze reference
NEA haze reference = room volume × 3.
| Floor area at 2.6m ceiling | Room volume | Smoke CADR reference |
|---|---|---|
| 12m² | 31.2m³ | At least 93.6m³/h smoke CADR |
| 20m² | 52m³ | At least 156m³/h smoke CADR |
| 30m² | 78m³ | At least 234m³/h smoke CADR |
| 38m² | 98.8m³ | At least 296.4m³/h smoke CADR |
| 40m² | 104m³ | At least 312m³/h smoke CADR |
A 300m³/h smoke CADR would correspond to about 100m³ of room volume under this rule, or roughly 38.5m² with a 2.6m ceiling. Aero's published 300m³/h figure is not identified as smoke CADR, so ULTI does not use that calculation as a haze-performance guarantee.
Generic CADR, particle CADR and smoke CADR
Check the label attached to a number. AHAM CADR commonly lists separate smoke, dust and pollen results. Other standards may publish a particle CADR. A product page may simply say CADR without naming the pollutant or method. These labels should not be silently treated as interchangeable.
When asking a seller, request the pollutant, test standard, fan setting and unit. Cubic metres per hour and cubic feet per minute are different units.
What 300m³/h looks like in common rooms
Dividing the published 300m³/h by room volume gives an illustrative clean-air-delivery comparison:
| Example room | Volume | 300m³/h ÷ volume |
|---|---|---|
| 12m² bedroom | 31.2m³ | 9.6 per hour |
| 20m² room | 52m³ | 5.8 per hour |
| 30m² room | 78m³ | 3.8 per hour |
| 40m² room | 104m³ | 2.9 per hour |
| 70m² open area | 182m³ | 1.65 per hour |
This is why an unexplained “up to 70m²” claim can mislead a haze shopper. The same purifier may be described for a large area at a low air-change assumption and for a much smaller area under a stricter target.
How to use a purifier during haze
- Check current Singapore air-quality information from haze.gov.sg.
- When outdoor conditions are poor, close doors and windows to slow the entry of haze particles.
- Place the purifier where its intake and outlet remain clear.
- Use an operating speed that provides meaningful airflow and that you can tolerate consistently.
- Wet-wipe or mop settled dust rather than stirring it back into the air.
- When outdoor air improves, ventilate the enclosed room. A purifier does not supply fresh air or control carbon dioxide.
HEPA filter claims need context
The APEX+ Aero lists H13 HEPA filtration. A filter grade alone does not establish a room-wide removal percentage. Whole-room results depend on how much air passes through the installed filter, whether air bypasses it and how quickly outdoor particles re-enter.
Activated carbon serves a different role from HEPA. It can help with selected gases and odours, but carbon presence alone does not establish removal of every gas produced during a haze episode.
Bedroom and living-room checks
For a bedroom
Check noise at the fan speed you plan to use overnight, display brightness and the path for power cables. Aero has a specified noise level of ≤55 dB, but no separate measured values for each fan speed or Sleep Mode. Ask ULTI before buying if sleep noise is critical.
For an open living and dining area
Measure the connected space rather than only the seating area. A corridor, kitchen opening or stairwell increases the effective volume and lets particles move between zones. More than one unit may be easier to position than one purifier behind furniture.
Frequently asked questions
Is 300m³/h enough for haze?
There is no universal yes or no. NEA's rule uses smoke CADR and room volume. Aero publishes 300m³/h CADR without identifying it as smoke CADR, so request the relevant test data for a smoke-specific decision.
Should I run the purifier on maximum?
Higher airflow usually gives faster clean-air delivery, but noise and power may also rise. Use the highest suitable setting you can operate consistently, following the manual.
Can I use floor area only?
Floor area is incomplete without ceiling height. A 20m² room with a 3m ceiling contains more air than one with a 2.4m ceiling.
Does a PM2.5 sensor replace the outdoor PSI?
No. The purifier reads conditions near its sensor, while Singapore's PSI is an outdoor regional index. Use each for its intended purpose.