There’s been worrying news for allergy sufferers recently, with reports that so-called ‘super allergies’ are on the way. Not only will these allergic reactions last longer – depressing enough for the estimated 21 million allergy sufferers in the UK – but they’ll also affect ‘even those who have not had allergies before’, explains Dr Bill Freeland, a leading allergy expert based at the London Allergy Clinic. So what’s going on – and what can you do to protect yourself?
DIESEL MAY TRIGGER YOUR ALLERGY
‘Most allergies are caused by inhaled, small water soluble proteins carried on dry particles such as pollen, or dust-mite faeces,’ says Dr Freeland, the expert who devised the scientific daily pollen count now included in weather reports.
‘Once these particles land on the mucosa, the membranes that line the airways, the allergen diffuses into it, setting up the reaction.’
Hay fever is up to twice as common in towns and cities as in the countryside, largely because of higher levels of traffic pollution, adding to irritation in the airways, according to charity Asthma UK.
‘It is not that people are allergic to pollutants, but this can make the situation worse for people who are already allergic to pollen,’ says Dr Hilary Longhurst, a consultant clinical immunologist at St Bartholomew’s Hospital in London.
And there is also evidence that the mucosal irritation caused by pollutants can ‘prime’ people who would not normally develop allergies to become allergic, adds Professor Sir Malcolm Green, founder of the British Lung Foundation.
He says the situation is being made worse at times by air pollution which is coming from fume-filled areas of Eastern Europe due to south-easterly winds (the UK’s prevailing winds are south-westerly).
The tiny particles of pollution (particulates) released by diesel fuel are considered particularly hazardous.
‘Pollutants, including diesel particles, which are really just minute globules of toxic tar, and ozone (formed by the effect of sunlight on nitrous oxide, a vehicle exhaust pollutant) irritate the lining of the lungs and make them more sensitive,’ says Professor Green. ‘So when an allergen such as pollen comes along, the lungs are already primed to react.’
In some cases, particulates may trigger allergies in people who did not have them before, he says. ‘Some people are “tipped over” into an allergic response because their lungs are sensitised by particulates.’
Pollution may even make some allergens more potent. A study in the journal Plant, Cell & Environment, found that ragweed plants exposed to high levels of nitrogen oxide, from power stations and vehicles, produced modified pollen that was more virulent, producing more severe or prolonged allergic reactions.
Ragweed, one of the daisy family, thrives along rivers and roadsides.
THE DOWNSIDE OF A LONG, HOT SUMMER
Airborne pollen is the most common cause of seasonal allergies – around 95 per cent of hay fever sufferers are allergic to grass pollen, for instance.
The temperature and the weather make a huge difference to the levels of pollen and other irritants such as diesel particulates and dust circulating in the air.
When it’s warm and dry, these particles stay suspended in the air for longer, entering the nose and mouth and landing on the delicate mucosal layer of the upper airways. Fourteen of the 15 hottest years on record have occurred since 2001, say the UN World Meteorological Organisation.
Last year was the hottest year since records began and 2016 is likely to be another record-breaking year, says Dr Grant Allen, a senior research fellow at the School of Earth, Atmospheric and Environmental Sciences at the University of Manchester.
‘And 2016 is expected to break that record again due to the compounding influence of the periodic El Niño, the warm phase of a recurring climate pattern that develops in the tropical Pacific.’
SYMPTOMS COULD LAST EVEN LONGER
It’s not just that the allergens could be hanging around in the air for longer, but there may be more pollen, too. The hay-fever season normally starts in January when the alder trees release their pollen and lasts through to September when nettle pollen disappears.
The peak season for grass pollen is usually mid-June, according to Beverley Adams-Groom, chief palynologist (pollen expert) and pollen forecaster at the National Pollen and Aerobiology Unit at the University of Worcester.
‘If the predicted combination of prolonged periods of warm, dry weather with intervals of some wet weather occurs, we’ll experience high grass pollen counts,’ she says. During the past ten years the ‘plant’ growing season has been getting longer as a result of warmer springs and summers, meaning that the pollen season is extending, too.
As Dr Mark McCarthy, manager of the National Climate Information Centre, explains: ‘Between 1861 and 1890, the average growing season by this measure was 244 days, and measuring the same period a century later, the average growing season had extended by just over a week.
‘For the most recent ten years between 2006 and 2015, the average growing season has been 280 days.’
Dr Jean Emberlin, of Allergy UK, adds: ‘There is substantial evidence from pollen monitoring records and vegetation surveys to show that the timing of some of the pollen seasons has been changing in the UK, getting earlier and lasting longer over the past few decades. In addition there has been a trend to increasing pollen loads of some types.’
Dr Longhurst points out that the severity of allergy symptoms are directly related to length of time of exposure, so ‘symptoms will be worse and also go on for longer’.
FOREIGN INVADERS MAKE IT WORSE
There are around 30 different types of pollen that cause hay fever and it is possible to be allergic to more than one type.
While most people with hay fever are allergic to grass pollen, warmer weather means there are more potential allergens, as it is helping non-native plants to thrive and some of these are highly allergenic. ‘Invading plants such as ragweed, which is the main cause of pollen allergy in the U.S., will be bringing increasing amounts of allergy-inducing pollen to Britain,’ says Dr Freeland.
Ragweed carries a potent allergen known as Amb a1 (antigen E) which is more irritating to the airways than either grass or birch pollen (another common cause of hay fever, with one in four sufferers affected by it).
The peak ragweed pollen season is mid September. ‘These allergens produce an abnormally vigorous response causing more severe symptoms,’ explains Dr Freeland.
Not every hay fever sufferer is allergic to ragweed, and currently our cool, damp summers keep it in check, but this is likely to change, as temperatures rise.
Christoph Sarran, a scientist at the Met Office, says that there is a possibility that warmer temperatures will prompt some allergenic species to start producing pollen twice in a single season. On the plus side, ‘some allergenic native species may reduce or disappear’.
ARE OUR IMMUNE SYSTEMS CHANGING?
More people than ever are affected by allergies, but it’s not clear why. One theory is that it’s down to children’s lack of exposure to bacteria because their environment is too clean, causing the immune system to overreact to harmless proteins such as those found in pollen grains.
‘This doesn’t answer all the questions, but it is the best explanation we have,’ says Dr Longhurst.
‘In the past, children played outdoors in the mud and muck and their immune systems learned to recognise harmful pathogens and distinguish them from harmless things. The price we pay for Western living standards is a rise in allergies of all kinds.’
HOW YOU CAN PROTECT YOURSELF
Holly Shaw, nurse adviser at Allergy UK, says that people can do a lot to help themselves.
She advises checking the pollen forecast in your area to plan your outdoor activities and avoid being outside when the pollen count is highest (usually early morning/evening).
It helps if you know what pollen types you’re allergic to so you can minimise your exposure and start treatment at the right time – this may simply be a question of guesswork, based on when your symptoms are most severe and which plants are pollinating.
According to Beverley Adams-Groom, hazel and alder come first in late January and February followed by the birch pollen season which typically starts at the end of March.
Grass pollen becomes a problem in May and peaks in mid June. Weed pollen and mould spores come into their own in late summer.
Holly Shaw also advises that people who suffer from hay fever keep doors and windows closed in peak pollen times.
‘If you need to go outside during times when pollen counts are high, wear wraparound sunglasses.’
A balm applied around the rim of your nostrils can act as a pollen trap. If you know the pollen count is going to be high, nasal steroid sprays can be used preventatively before your symptoms start, says Holly Shaw.
The symptoms themselves can be ‘effectively managed by taking a daily non-sedating anti-histamine, which reduces inflammation in the lining of the nose and throat,’ she says. ‘Your GP or pharmacist will be able to advise on the correct medication choice for the severity of your symptoms.’
While pollen forecasts do not currently reflect pollution levels, there is a daily air quality index (published by the Department for Environment, Food & Rural Affairs) that shows where areas of pollution in the UK are high, with forecasts for up to five days available.