2023-05-03 17:58:21
Itchy eyes, itchy nose, itchy throat. Every year, spring begins the same way for Olivia: with a severe hay fever and bursts of sneezes that make her friends laugh – she, much less. “At first it was only when I was spending a weekend in the countryside, then it started to take me to town. It could take weeks.” says this 35-year-old lawyer, who finally resorted to desensitization, a treatment which consists of administering increasing doses of the allergen over several years in order to stimulate the immune system. “Since then, I’m only embarrassed two or three days a year”, she savors.
Like Olivia, 18 million French people struggle with allergic symptoms: rhinitis, asthma, eczema, conjunctivitis… According to the World Health Organization (WHO), half of the population on Earth will be affected by 2050, compared to 25 to 30% today and less than 3% in 1970.
If this reaction of the immune system is based on a genetic ground – we speak of atopy –, the environment is the first responsible. “These are mainly respiratory allergies linked to pollens and, to a lesser extent, dust mites and moulds”, explains Samuel Monnier, engineer at the National Aerobiological Surveillance Network (RNSA). In early May, the association placed eleven French departments on red alert for the risk of pollen allergies.
“At the end of May, beginning of June, all of France is on red alert”
But these risks now exist all year round. Blame it on climate change, which causes the lengthening of the pollen seasons and the early flowering of certain allergenic trees such as the hazel tree. “There are two parameters to take into account in global warming, details Samuel Monnier. On the one hand, the rise in temperatures, which leads to the emission of greater quantities of pollen ; and on the other hand, the concentration of CO2 in the atmosphere, which boosts the growth of trees and promotes the production of more numerous and more allergenic pollens. »
To each region its species hated by serial sneezers: “Birch in the north of the country, cypress and olive trees in the south, ambrosia in Auvergne-Rhône-Alpes…”, lists the engineer. Grasses, these herbaceous plants that adorn parks and roundabouts, do not spare any part of the territory. “At the end of May, beginning of June, all of France is on red alert”says Samuel Monnier.
In Guadeloupe, the effect of these pollens on respiratory health is combined with that of sand mists and Sargassum algae, which can cause skin reactions or irritation of the respiratory mucous membranes. “Right now, half of the people hospitalized in my department are for an allergic asthma attack,” thus testifies Professor Chantal Raherison-Semjen, pulmonologist at the Pointe-à-Pitre University Hospital.
In the eyes of the former president of the French-speaking Pneumology Society, certain signs tend to be trivialized, at the risk of seeing the allergy degenerate into a chronic pathology. “Faced with evocative symptoms such as wheezing, doctors should have the reflex to request an allergological assessment, because this discomfort can be the inaugural of an asthma attack”, reports the pulmonologist.
“The first source of pollution is the interior”
Today, it takes seven years on average between the appearance of the first symptoms and the first consultation with an allergist. No wonder according to Professor Frédéric de Blay, pulmonologist-allergist at the University Hospitals of Strasbourg. “Like all specialists, the number of allergists has dropped: there are only 1,000 left. That’s not a lot to take care of 30% of the population”, points to the doctor, who speaks of“silent epidemic”.
At the head of the French Federation of Allergology, he is working with the Ministry of Health to create a care pathway based on several professionals, including medical advisers in the indoor environment. Still not very widespread, these practitioners go to the homes of allergic patients to identify the presence of mold or chemical pollutants, but also to help them organize their space, “for example an anti-dust mite chamber”says Professor de Blay, inventor in 1991 of this profession which now has 200 representatives in France.
“We often talk about air pollution, but contrary to popular belief, the primary source of pollution is indoors,” insists Frédéric Le Guillou, president of the Respiratory Health France association. To avoid the onset of allergies, this pulmonologist recommends regularly ventilating your home, limiting heating – “the first source of microparticle pollution, in front of the car! » –, to avoid open fires or scented candles. “Whether to protect yourself from a virus like Covid or from pollen, wearing a mask during the pollen period can be very useful because it will filter around 70% of the particles”, adds the specialist.
In cities, green spaces to be redeveloped
Simple gestures on which the authorities do not communicate enough, believes Chantal Raherison-Semjen. “Globally, guardianship tends to underestimate the environmental dimension of respiratory diseases”regrets the pulmonologist, citing the still unknown impact of thunderstorms on allergies. “Their occurrence during the pollen season leads to the fragmentation of the pollen which then becomes more allergenic. In Australia and Britain, this has led to veritable epidemics of asthma attacks,” she warns.
For his part, Samuel Monnier is campaigning for the development of green spaces to take better account of the health dimension.. “Some cities continue to plant birch trees, which are very allergenic, in large quantities. In Mulhouse, you can find them at all the roundabouts. In Lyon, we have just planted 400 in a new park. It is true that it is pretty with its beautiful white trunk, but there are alternatives”, raises the specialist, who refers to the information guide on urban vegetation developed by the RNSA to guide municipalities.
Birch or not, urban life favors the development of allergies, including food allergies – the latter doubled between 1980 and 2000. “This is not only due to pollution, but to many other factors such as maternal stress during pregnancy, the microbiota…”, emphasizes Professor de Blay. “Too much hygiene also promotes an imbalance in the parasite balance and therefore the development of allergies, adds Frédéric Le Guillou. Conversely, several studies show that certain communities, which live in contact with animals, have no allergies and almost no asthma because their immune system is educated. »
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Allergy, fourth disease in the world
According to the World Health Organization (WHO), allergy is the fourth most frequent disease after cancer, cardiovascular pathologies and AIDS.
The appearance of an allergy occurs in two stages. First a first phase of sensitization to the allergen which goes unnoticed, then a second phase of revelation during which the symptoms are triggered.
Whatever its origin (air, food, drug, etc.), this hypersensitivity to certain allergens can manifest itself at all ages of life. In the most serious cases, it gives rise to anaphylactic shock, requiring an injection of adrenaline.
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