Summary and product recommendation
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Allergy sufferers should use an air purifier that is powerful enough to drag all of the air in the room through the filter a minimum of 4 times an hour (ACH) for it to be genuinely effective. To get around 4 air changes per hour in your room measuring between 51 and 60 m2 you need an air purifier with a clean air delivery rate (CADR) in the range of 500-599 m3/h. CADR rating indicates how fast an air purifier can clean the air within a particular size room. It provides a way to compare air purifiers taking into account both airflow and a filter's efficiency.
An air purifier with a HEPA type (H10-12) filter is sufficient for most allergy sufferers as it captures up to 95% of airborne particles greater than 0.3 microns.
Most common allergens like pollen, mould spores, pet dander and dust mite faeces range from about 100 microns down to around 0.3 microns and so are easily filtered out by a HEPA type air purifier.
This tool is for guidance only and does not replace professional advice on product selection.