Do air purifiers help with hay fever? What the NHS and Allergy UK say

Short answer

An air purifier can catch pollen-sized particles from the air in one room, but it doesn’t treat hay fever, and the NHS hay fever page doesn’t mention purifiers at all. The NHS advice is to keep pollen out of your home and to ask a pharmacist about treatment. Allergy UK suggests purifiers mainly for year-round indoor allergies; for seasonal hay fever, its tips are to check pollen forecasts and limit your exposure.

In the UK buyer discussions we read, hay fever was the most common reason for buying an air purifier, often for a bedroom. This page sets out what the official guidance says, what a filter can and can’t catch, and what to look for if you decide to try one alongside the NHS steps.

What the NHS says

The NHS hay fever page gives no advice on air purifiers. Its self-help steps are about keeping pollen out of your home and off you:

• keep windows and doors shut where possible
• vacuum regularly and dust with a damp cloth
• use a vacuum cleaner with a HEPA filter, and a pollen filter in your car’s air vents
• shower after you have been outside

The NHS says symptoms are usually worse between late March and September, especially when the weather is warm, humid and windy. Its allergies page lists tree and grass pollen among the common allergens, and its first advice for any allergy is to avoid the trigger where you can.

What Allergy UK says

Allergy UK, the allergy charity, draws a line between two kinds of allergic rhinitis on its hay fever page. For year-round (perennial) rhinitis caused by indoor allergens, it suggests air purifiers along with better indoor air and frequent cleaning. For seasonal hay fever, its tips are to check the pollen forecast and limit your exposure.

Its indoor air quality factsheet says running an air purifier continually, as the maker instructs, can help reduce airborne allergens such as dust mite allergen, mould spores, pet dander, VOCs and smoke. That is the furthest the UK guidance we read goes, and it is about reducing what is in the air, not about symptoms.

Allergy UK also endorses products through Allergy Research Ltd, its trading company: manufacturers apply, and products are reviewed or tested before approval. Its approved products directory can be filtered to air purifiers, and each entry names the model and lists the triggers it was assessed for.

What the wider evidence says

The government’s Committee on the Medical Effects of Air Pollutants (COMEAP) looked at this in its December 2025 response on indoor air quality. It cites a 2021 systematic review that found portable filter-based air cleaners cut indoor fine particles (PM2.5) in the short term, but that the direct evidence of health benefits was weak. It also notes that NICE’s indoor air quality guideline looked at air filters and purifiers and made no specific recommendation, because homes vary too much.

The US Environmental Protection Agency adds a practical point about allergens: larger particles such as pollen, dust mite allergen and pet dander mostly settle on surfaces, so an air cleaner only catches them once they are disturbed back into the air.

What a HEPA filter catches

Pollen is one of the larger particles an air filter deals with. The US standard test for air cleaners, AHAM AC-1, measures three separate clean air delivery rates: one for tobacco smoke (about 0.09 to 1 micron), one for fine dust (0.5 to 3 microns) and one for pollen (0.5 to 11 microns), standing in for small, medium and large household particles.

A HEPA filter is rated at the size it finds hardest to catch. In the US, HEPA means removing at least 99.97% of particles of 0.3 microns, the most penetrating size, and the EPA says larger and smaller particles are caught even more efficiently. So a pollen-sized particle that reaches a HEPA filter is very likely to be caught. The limit is not the filter but the air: a purifier only cleans what passes through it, and how much of the room’s air that is depends on its CADR and the size of the room.

What a purifier can’t do

• Clean pollen off you or your bedding. Pollen on clothes, hair, bedding and floors stays there until it is disturbed back into the air. That is why the NHS steps are about showering, vacuuming and damp dusting.
• Replace fresh air. A purifier recirculates the air in the room. It brings in no fresh air from outside, and the government’s 2020 SAGE-EMG paper says air cleaners are never a reason to cut ventilation.
• Clean the whole house. SAGE-EMG notes that a unit that works in a small room may do little in a large one. One purifier covers one room.
• Treat symptoms. It is not a medicine. For symptoms, the NHS points to a pharmacist, and to a GP if they get worse or don’t improve.

An ioniser adds nothing here. The US EPA says ion generators may do little for pollen and dust allergens and, like some other electronic cleaners, can produce ozone, a lung irritant. SAGE-EMG did not recommend ionisers unless their safety is proven.

Windows: shut, or opened briefly?

The advice pulls two ways, and it helps to see why. For hay fever, the NHS says keep windows and doors shut where possible. For dust mites and mould, Allergy UK advises ventilating to bring humidity down, including opening windows, especially in bedrooms. Asthma + Lung UK offers a middle way: air rooms for a few minutes at a time, and check pollen and pollution levels first if they are your triggers. A purifier doesn’t change this, because it adds no air from outside.

When pollen is in the air

The Met Office says the UK pollen season normally runs from March to November. Symptoms usually start once the count passes 50 grains per cubic metre of air, and 50 to 150 grains of grass pollen counts as high. Allergy UK describes tree pollen in spring, grass in summer and weeds in autumn, and suggests checking the forecast every day.

The Met Office publishes the UK pollen forecast and is moving to forecasts for your exact location, hour by hour and by pollen type. For air pollution, Defra’s Daily Air Quality Index runs from 1 to 10 in four bands, with health advice for each.

If you decide to try one

If you want to try a purifier as well as the NHS steps, these choices follow from the guidance above:

• Choose a mechanical filter. A filter with a named class, such as H13 under BS EN 1822, tells you the most; H13 is the minimum the Department for Education sets for classroom air cleaners. Many home purifiers name no class, including the three below, so you rely on the maker’s own figures.
• Size it for the room. Our rule: room size in m² is roughly the CADR in m³/h divided by 12, about five air changes an hour. A 12 m² bedroom needs a CADR of about 145 m³/h. See what size air purifier you need.
• Put it where you spend the most hours, usually the bedroom, and run it as the maker instructs. A quiet lowest setting matters if it runs overnight.
• Skip the ioniser, or choose a model that lets you switch it off.
• Budget for filters. Depending on the model, the main filter is due anywhere from every six months to every few years. See replacement filters explained.

Three of our quiet bedroom picks suit a typical bedroom. The Coway Airmega 150 is on Quiet Mark’s UK list and Coway rates its Silent mode at 20 dB. The Philips AC2220 quotes 13 dB on its lowest setting and can switch every light off. The Levoit Core 300S adds app schedules and a display that switches off. You can compare all of them in our air purifier comparison.

Hay fever and air purifier questions

Will an air purifier help with dust mite or pet allergies?

It can reduce what is in the air, but not what has settled. Allergy UK suggests purifiers for year-round allergies caused by indoor allergens, and says running one continually can help reduce airborne dust mite allergen and pet dander. The US EPA notes that these allergens mostly settle on surfaces, so cleaning matters too: Asthma + Lung UK says a HEPA-filter vacuum traps more house dust mites than an ordinary one.

Does an Allergy UK Seal of Approval mean a purifier helps hay fever?

Not on its own. Allergy UK’s approved products directory lists the triggers each approved model was assessed for, so check whether pollen is one of them. The scheme is run by Allergy Research Ltd, Allergy UK’s trading company, which gives its profits to the charity: manufacturers apply, and their products are reviewed or tested before approval. A seal is about the product, not a promise about your symptoms.

Do I need a carbon filter for hay fever?

Not for pollen. Pollen is a particle, and the particle filter is what catches it. Activated carbon is there for gases and smells: the US EPA says air cleaners without a sorbent such as activated carbon won’t remove gaseous pollutants. A carbon layer is worth having if you also want to tackle cooking or pet smells, but it isn’t the part that deals with pollen.