Why hay fever is worse this year - and what you can do about it

Almost exactly 200 years ago, a London-based doctor called John Bostock noticed he would get an itchy throat, sore watering eyes, and an irritated nose during warmer months.

He found 28 other patients suffering with the same symptoms, without explanation. He coined the term hay fever, but it wasn't until 1859 that scientist Charles Blackley, suffering from symptoms himself, correctly hypothesised that pollen was to blame.

Fast forward to the modern day and it's estimated around 13 million people in the UK are suffering from hay fever - and research suggests it could get worse.

Here is a look at how pollen causes hay fever, when the season is and why it could feel worse for sufferers this year.

What causes hay fever?

Hay fever is essentially an allergy to pollen, the fine powder plants produce as part of their reproductive cycle.

Pollen contains proteins and people have an allergic reaction to these proteins - hay fever being one of those reactions, along with allergic asthma and eczema.

The symptoms are caused when the immune system reacts to pollen in the body to produce histamine and other chemicals, according to the Met Office.

Hay fever is most commonly caused by grass pollens, although other pollens, of which there are around 30, can also trigger symptoms.

Insects and the wind help spread pollen, and the weather hugely impacts how much pollen is released and spread around.

Hay fever sufferers may hope for rainy days, when pollen can be cleared from the air, whereas it spreads easily on hot, humid and windy days.

The pollen count is highest in the early evening on sunny days and that's when you are most likely to suffer from hay fever symptoms, the Met Office says.

When is hay fever season?

There are three different types of hay fever seasons, triggered by different types of pollen.

Tree pollen comes first, typically from late March to mid-May, affecting around 25% of hay fever sufferers.

Grass pollen affects the majority of hay fever sufferers due to around 150 types of grass pollen flowering simultaneously. It has two peaks, and its season typically lasts from May until July.

Weed pollen is the third trigger, and it can be released at any time, though the season typically covers the end of June to September.

Why is it worse this year?

It is the tree pollen phase of hay fever season between March and mid-May that will be more severe for sufferers, says Dr Beverley Adams-Groom, senior palynologist and pollen forecaster at the University of Worcester.

She tells Sky News people will likely suffer more severe symptoms due to a particularly high pollen count, adding it's down to two factors.

"First of all, trees that produce allergenic pollen in the UK tend to have alternating high and low years of severity - this year is a high year," she says.

"Secondly, there was suitable weather for high pollen production last summer when the pollen was set in the buds."

It was a particularly warm and dry June, meaning more pollen was produced in birch, leading to a more severe tree pollen season, she explains.

She says central regions of the UK are particularly affected. Southern and eastern regions are being affected less due to periods of cold winds in the spring that tend to reduce the amount of pollen released.

She says grass pollen season is likely to be around average this year, but it's a bit too early to know for certain.

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Why it could get worse long-term

Climate change could make hay fever worse in a number of ways, according to UK Health Security Agency (UKHSA) research:

• Changes in temperature and rainfall may lengthen the UK pollen season and potentially make pollen concentrations higher
• It could change the potency of pollen, making single pollen particles a more threatening allergy-causing agent
• Climate change affecting the geographical distribution of allergenic plants, with invasive species such as ambrosia (common ragweed) being on the watch list. A single ragweed plant can produce a billion grains of pollen per season and its pollen causes strong allergic reactions.

Climate change is already having an impact, according to Dr Adams-Groom, because it's leading to the sort of warmer June temperatures we saw last year, which led to a higher pollen count.

How can hay fever be treated?

There is unfortunately no cure for hay fever, and you can't prevent it, so the only option for sufferers is to try and manage its symptoms.

Tips on easing the symptoms include:

• Put Vaseline around the nostrils to trap pollen
• Wear wraparound sunglasses to prevent pollen getting into the eyes
• Stay indoors whenever possible
• Get advice from pharmacists on treatments including antihistamine drops, tablets or nasal sprays.