Frequently Asked Questions

UK hay fever season typically runs from late March to September. Tree pollen peaks from March to May, grass pollen, the most common trigger, peaks from May to July, and weed pollen peaks from June to September. Exact timing shifts with region and weather, and milder winters tend to bring an earlier start. The Met Office publishes a national pollen forecast you can check daily.

Yes. A filter removes airborne particles from the air that passes through it, and studies of indoor environments consistently find that an appropriately sized unit lowers measured pollen and fine particulate levels. A MERV-13 filter captures the pollen grains, dust-mite debris and mould spores that drive most UK symptoms. The effect is strongest in an enclosed room with the unit running continuously.

The main indoor triggers are dust mites, which thrive in humid British homes, cat and dog dander, mould spores such as Aspergillus and Penicillium in damp conditions, and grass pollen carried in through open windows during summer. These particles range from under one micron up to tens of microns, which is why a broad-spectrum MERV-13 filter is well suited to UK conditions.

Not for everyday allergy relief. Denser filters capture more per pass but resist airflow more strongly, so a unit can clean a room more slowly. MERV-13 sits at the practical sweet spot, combining high capture with strong airflow, which usually produces the largest real reduction in airborne allergens over an hour. That balance matters more than a higher number on paper.

CADR, or clean-air delivery rate, measures how quickly a purifier delivers filtered air, expressed in cubic metres per hour. It matters because a filter only cleans the air that passes through it, so a higher delivery rate relative to your room volume means the room's air is cleaned more times per hour and the particle level falls further. Aim to process your room volume several times each hour.

Calculate your room volume by multiplying length, width and height in metres. Then choose a purifier that can process that volume several times per hour. For example, a 4m by 5m by 2.5m room is 50 cubic metres, so a unit delivering a few hundred cubic metres of clean air per hour will refresh it multiple times hourly. Higher airflow gives you more headroom in larger or busier rooms.

In the UK's humid climate, plan to replace a MERV-13 filter roughly every six to nine months with normal use, or more often during peak pollen season if you run the unit continuously. Homes with pets or damp may need changes more frequently. A pre-filter or mesh guard captures larger particles first and helps extend the life of the main filter.

Reducing indoor triggers such as dust mites, pollen and pet dander can support a calmer home environment, and the NHS recognises air filtration as one useful environmental control measure. It is not a treatment for asthma. Combine it with other measures such as allergen-proof bedding and humidity control, and always follow the guidance of your GP or asthma nurse for managing the condition itself.

It can help. Dust mites thrive in humid UK homes, and their allergenic debris becomes airborne when rooms are disturbed. A MERV-13 filter captures these particles from the air. For best results, combine air filtration with weekly hot washing of bedding, allergen-proof mattress covers and keeping indoor humidity in check to discourage the mites at source.

No. An air purifier is an environmental control measure that reduces your exposure to indoor allergens. It is not a medical device or treatment and does not replace advice from a pharmacist or GP. If your symptoms are persistent, severe or not controlled by usual measures, speak to a healthcare professional about the right treatment for you.