Can Ventilation Help You Breathe More Easily During Hay Fever Season?

Hay fever can turn spring and summer into a miserable time for millions of people.

Sneezing, streaming eyes, congestion and an itchy throat are familiar symptoms, but hay fever can also disturb sleep, affect concentration and worsen existing respiratory conditions.

Allergic rhinitis, the medical term for hay fever, affects an estimated 26% of UK adults and between 10% and 15% of children. Recent Allergy UK research has suggested that almost half of people experience hay fever symptoms to some degree, with those who suffer from eczema or asthma more likely to also have hay fever.

Hay fever is not only common, but on the rise, cases having trebled in the last 20 years.

What causes hay fever?

Hay fever is an allergic reaction to pollen, most typically when it enters the mouth, nose, eyes and throat. It normally begins during childhood, but people of any age can develop hay fever.

Not all pollen triggers hay fever. Sticky pollen from flowers which has evolved to be carried by insects generally isn’t a problem for hay fever sufferers. It’s the airborne pollen from trees, grasses and weeds, which rely on the wind to spread that’s the one to watch.

The pollen season can extend across much of the year. Tree pollen is generally most prevalent from March to mid-May, followed by grass pollen from mid-May to July and weed pollen from late June into September. Grass is the most common hay fever trigger in the UK. Research from the UK Health Security Agency also indicates that some pollen seasons are beginning earlier and may last longer, meaning symptoms are no longer confined to a few weeks in summer.

Why does pollen become a problem indoors?

Although pollen originates outdoors, it can easily enter the home through open windows and doors. It is also carried inside on clothing, shoes, hair and pets.

This presents a dilemma during warmer weather. Opening windows may make the home feel fresher, but it can also provide a direct route for airborne pollen. Allergy UK therefore recommends keeping windows closed when pollen levels are high, as well as changing clothes and showering after spending time outdoors.

Can mechanical ventilation help?

Mechanical ventilation, be it a single room fan or a whole home system, can help reduce the amount of pollen in the home, along with other pollutants, whilst also maintaining a comfortable environment.

The most appropriate solution will depend on the nature of your property, including its construction and size, the existing ventilation provision and the number of people living within it.

Mechanical extract fans in kitchens, bathrooms and other ‘wet rooms’ as they are known, help remove humid, stale and polluted air at source. This supports a healthier indoor environment and can reduce the need to open windows for prolonged periods when pollen levels are high.

Continuous mechanical extract ventilation fans provide low-level ventilation throughout the day, with increased airflow when additional extraction is needed. By continually removing stale and moisture-laden air, they can help create more consistent indoor conditions.

For new build properties, Mechanical Ventilation with Heat Recovery (MVHR) provides both extract and supply ventilation. Stale air is removed from areas such as kitchens and bathrooms, while fresh outdoor air is supplied to living rooms and bedrooms. Before entering the home, the incoming air passes through filters, which can help reduce the amount of airborne pollen and other particles entering through the ventilation system. Because there is considerable ductwork involved, this solution isn’t suited to existing properties unless they are undergoing major renovation.

Positive Input Ventilation (PIV) may also be suitable for some existing homes. It introduces a continuous supply of filtered air, helping to dilute and displace stale, humid and contaminated indoor air.

Can ventilation prevent hay fever?

Mechanical ventilation can reduce reliance on open windows and, where filtered supply air is provided, help limit the amount of pollen entering through the ventilation system. It can therefore form a useful part of a wider strategy for managing allergens in the home.

Alongside checking the Met Office pollen forecast, keeping windows closed when pollen counts are particularly high, changing clothes after spending time outside and regularly cleaning the home, suitable ventilation can help create a fresher and more comfortable indoor environment throughout the hay fever season.