The hottest day of the year has got to be good news, right? Not for Ireland’s one million hay-fever sufferers.

Though the tree pollen season is over, Met Éireann advise the grass pollen count will be "high" across the provinces today. Weed pollen will be at low to moderate levels and fungal spores will be high.

"Pollen is released in the morning and carried higher into the air by midday," says Dr Paul Carson. "It descends again to 'nose-level' in the late afternoon so avoid those peak times if heading outside," he advises.

One in five people will be affected by hay fever at some point in their lifetime, so what exactly causes hay fever and how can you minimise the symptoms?

What is hay fever?

Hay fever is an allergy to airborne particles such as pollen and fungal spores that affects the nasal passages, eyes and lungs, causing sneezing, an itchy, runny or congested nose, watering and sore eyes, aching sinuses and a wheezy cough.

It occurs when an allergen, such as pollen, causes your body to defend itself by producing antibodies.These antibodies then bind to mast cells, a process which releases a chemical called histamine.

The chemical causes dilation of nasal blood vessels and inflammation of the mucus membranes, which is why you sneeze a lot and get stuffy sinuses.

The symptoms can interfere with sleep and make it hard to concentrate. You can be allergic to tree pollen (released in spring), grass pollen (released from the end of spring into summer) and weed pollen (released in late autumn).

So, what can you do?

The best treatment for this is to avoid the allergen responsible, but when this isn’t possible there is medication available to help alleviate symptoms. Antihistamine medication, for example, binds to receptors and works by blocking the binding of the cells which produce histamine. Corticosteroids and decongestants may also help.

Putting a smear of Vaseline inside each nostril to ease the soreness and to capture pollen entering the nasal passages can be effective. And try the aloe vera version to soothe your over-wiped nostrils.

Of the one million hay-fever sufferers in Ireland, 85 per cent of them self-medicate. But while so many of us self-medicate for hay fever, how do we know which is the right treatment to go for?

Earlier in the season Carson – who has 30 years experience dealing with allergies – launched a free app, developed by MedApp Ltd. The app, named Hay Fever Relief, gives hay fever sufferers immediate information about their symptoms and pollen counts so they can determine the severity and nature of their ailment and the best treatment. It allows users to explore 3D imagery of the nose sinuses, ears and chest.

By inputting symptoms into the app, sufferers can have their hay fever symptoms graded by severity with and then recommended the best treatment. The app also provides information on pollen counts nationally and internationally, helping sufferers anticipate bouts of hay fever even when travelling abroad.

Other tips to deal with hay fever:

• Avoid areas of lush grassland
• Keep house and car windows closed during peak pollen hours of late morning and late afternoon
• Wear wrap-around sunglasses to reduce pollen grains affecting the eyes
• If you can, avoid being outdoors late morning and late afternoon
• Don't smoke and keep away from smokers (passive smoking aggravates all allergies)
• Get someone else to mow the lawn or wear a face mask if you have to cut the grass.
• Never sleep with the bedroom window open.
• Don't drive with the window open.
• Put used tea bags in the fridge. They make great soothing compresses to relieve swollen or puffy eyes.
• Freshly cut cucumber slices along the closed eyes soothe skin and eye irritation
• Keep an antihistamine handy for sudden allergy attacks

When all else has failed and you are facing your wedding day with swollen eyes and streaming nose, you can get oral steroids from your GP. It is only a short-term fix, and repeated or prolonged courses are harmful, but it will get you down the aisle.

There is also a link to food sensitivities, according to Carson. If you are prone to food sensitivities or food-related allergies, these could be interlinked with your hay-fever symptoms. For some people the identification of problematic foods and ingredients can help to relieve or reduce hay-fever symptoms. Food groups such as dairy can cause extra congestion in some people.

Also, if you’re allergic to birch pollen you may also react to celery, curry spices, raw tomato, raw carrot, apples, pears, and kiwi fruit. If you’re allergic to grass pollen you may also react to oats, rye, wheat, kiwi fruit and raw tomato. If your allergy is to weed pollen you may also react to raw carrots and curry spices.

The following foods and drinks contain high levels of histamine and should be avoided as part of your overall management.

• Fish: tuna, sardine, anchovy, mackerel.
• Cheese: Emmenthal, Harzer, Gouda, Roquefort, Tilsiter, Camembert, Chedder.
• Hard cured sausages including salami and dried ham.
• Vegetables: pickled cabbage, spinach, tomatoes and tomato ketchup.
• Alcohol: red wine (especially deep and heavy reds), white wine, sparkling wine, beer.

Sympathy

Unfortunately, if you do suffer from hay fever in the coming days, don’t expect much sympathy in work. A UK study found bosses offer less sympathy to workers with hay fever than they do to those with hangovers.

A study of 1,540 working hay fever sufferers and non-sufferers shows almost half (42 per cent) of those with the pollen-triggered condition say colleagues who come to work feeling worse for wear after a few drinks the night before receive more sympathy than they receive.

One-third (33 per cent) of sufferers claimed they “get no sympathy whatsoever” from their boss – while a quarter (26 per cent) claimed co-workers don’t offer any kind words – and 28 per cent say they hate the way people belittle the condition.

One in 10 the non-sufferers studied claimed they did not think hay fever is even a “real condition”.

Despite the lack of recognition, one fifth of those who suffer with summer sniffles (18 per cent) claim their hay fever “really gets them down”.

The UK study, commissioned by eye care specialist Optrex, also showed over a quarter of sufferers (27 per cent) believe hay fever is not taken seriously by friends and colleagues.