Pollen: everything you need to know

Spring may be a little late this year, but the good news for people with hay fever is that the pollen season is following suit – and it may be shorter than usual. Remarkably for the time of year, there is little pollen about and the current forecast (for tree pollens, the earliest type) is low.

Beverley Adams-Groom, from the National Pollen and Aerobiology Research Unit (NPARU), which provides the pollen count, says that the exceptionally severe winter followed by a wet, cold spring, means most plants are flowering later than usual. With 15 million in the UK estimated to have hay fever, this year's later, possibly shorter pollen season is a welcome blip in the long-term trend towards earlier, longer seasons.

"Unusually, we're in a bit of a lull at the moment," says Adams-Groom. "Hazel and alder pollen have finished, and the birch pollen season typically starts at the end of March but it is two or three weeks late." Birch is second only to grass as the UK's most severe allergen, affecting 25% of people with hay fever. Fortunately, she adds, birch may well be a short season, which could be the case with other pollens, including grasses (which normally start in May). "But none of this is set in stone. If we have a warm, wet May the grasses might catch up."

Adams-Groom is the NPARU's chief palynologist (palynology is the study of pollen). She takes me to see the unit's pollen traps: perched on the roof, they look a little like aliens. Each one has three legs, a weather vane for a head and a rotating drum for a body, with a slit large enough for pollen grains (but not insects) to get through. Once inside the drum, any pollen gets caught on a roll of sticky tape, sections of which are regularly removed and mounted on a microscope so that the grains can be painstakingly counted.

These seemingly primitive devices, found on rooftops at 18 sites around the UK, are used by researchers to work out the daily pollen count – the average number of pollen grains per cubic metre over 24 hours. The unit's national and regional pollen forecasts – given as low, moderate, high or very high – warn people with hay fever just how miserable their day is likely to be. Most people start getting symptoms when the forecast is moderate (30 to 49 grains of pollen per cubic metre of air).

While the NPARU is best known for pollen monitoring, its work nowadays is more wide-ranging. In a £7m state-of-the-art laboratory complex at the University of Worcester, researchers test anti-allergy products, such as vacuum cleaners and air ionisers in a climate-controlled chamber, as well as designing clinical trials of hay fever remedies.

But hay fever can be hard to treat because the ways allergies affect us can be so complex. Some pollen allergies are cross-linked to allergies to particular foods, which can cause symptoms such as itching and swelling in the mouth and lips. "People with a birch pollen allergy may get a cross-reaction to apples and other raw stoned fruit, while a ragweed allergy is linked to a reaction to melons," says Professor Jean Emberlin, who set up the NPARU. It is thought that the submicroscopic proteins in certain foods are chemically similar to airborne allergens. If you suspect this is a problem for you, you may need to see a specialist. Some of the allergens in food are destroyed by cooking, although some people are advised to avoid certain foods altogether.

The latest theory is that we should be measuring not just pollen grains, but the proteins in pollen that trigger allergy. Scientists have long suspected that the pollen count may not accurately reflect the levels of allergen in the air, which may help to explain why some people get symptoms even when pollen counts are not high. A large EU-funded study is currently under way.

How to handle hay fever

Identify your problem pollen

Knowing which type of pollen causes your allergy means you can minimise exposure, and start treatment at the right time. This can be tested by a GP or at a specialist centre, "but the simplest way to do it," says Professor Jean Emberlin from NPARU, "is to keep a pollen diary." If you notice symptoms during April, you're probably allergic to tree pollen; May, June and July indicate allergy to grasses. Weed pollen and mould spores come into their own in late summer.

Pollen avoidance

Check your local pollen count (pollenforecast.org) and, if it is high, stay indoors with the windows closed, or at least away from heavily planted open spaces. Levels are usually highest in the mornings and on windy days. If you do go out, shower and wash your hair once you get home. You can also try wrap-around sunglasses if you suffer from itchy eyes. Stay indoors when the grass is being mown, and bring in washing before pollen levels increase at night. Plan a holiday by the sea or somewhere where pollen seasons are earlier, to avoid symptoms.

Drug treatments

"It's best to consult your pharmacist or GP on what's best for you," says Emberlin. They include antihistamine tablets and nasal sprays, which calm the body's allergic reaction – older tablets can cause drowsiness, so choose a newer type such as cetirizine or loratadine, both of which can be bought over the counter. Corticosteroid nasal sprays (over-the-counter versions include beclometasone and fluticasone) can relieve a runny or blocked nose; for maximum effect start taking them a fortnight before you expect to get symptoms. These sprays can cause mild irritation and nosebleeds in some people and should not be taken in high doses for lengthy periods. Eye drops containing sodium cromoglicate (Opticrom Allergy) or antihistamines (Otrivine) will help with itchy eyes.

Drug-free treatments

So far, few non-drug treatments have been proven effective against hay fever, says Emberlin, although Nasaleze (a cellulose-based powder which is sprayed up the nose, to form a barrier) has helped reduce reliance on medication in a placebo-controlled trial. A handheld device used to shine light into the nostrils has also shown some success and is available in some chemists. "We don't know how it works really but it seems to increase blood supply to the nasal membranes," says Emberlin. A recent small study has shown that HayMax, a balm used to coat the nostrils, can trap pollen grains, but far more research is needed to see if it reduces hay fever symptoms. Meanwhile, you could always try Vaseline.