Health. Pollen allergies: why it's (even) worse this year... especially in the city!

Itchy eyes, runny noses, sneezing fits... in mid-May, grass pollen is abundant. And if you feel like it's "worse" this year, it might not be just a figment of your imagination.

For now, according to the brand new "pollen index" developed by the Atmo network , the risk of allergies is "high" across almost the entire country. A situation that is expected to continue in the coming days, and even worsen.

Specifically, it is currently grass pollen that is causing severe allergies. This follows birch pollen, whose season has started earlier than usual.

Grasses, on the other hand, comprise a very large "family" of plants: more than 10,000 species. These plants are as diverse as forage grasses (ryegrass, couch grass, vernal grass, cocksfoot, etc.), cereal grasses (wheat, oats, rye, etc.) and even ornamental grasses (fescue, pampas grass, canary grass, etc.). As a result, they are found everywhere in France, in meadows, fields, gardens, but also in cities with parks, public gardens and other lawns.

In spring and summer, they release small, wind-borne pollen that easily comes into contact with the mucous membranes of the nose and eyes. These pollens, with their high allergenic potential, can cause allergic rhinitis and even asthma in a significant number of people.

The weather, occasionally, sometimes explains periods of stronger allergies. But it is rather on the side of global warming that we must look: by favoring an earlier mildness, it plays a role in the production of pollen, which appears earlier and in greater quantity. Consequence: peaks... at more than 2,000 grains per cubic meter, when the alert threshold is at 80. A higher concentration of CO ₂ in the air in fact increases the quantity of pollen. Shorter winters also favor a greater production of pollen , over a longer period, further accentuating the phenomenon.

It is now established that the population allergic to pollen continues to grow : from around 1% in the 1960s, around a third of adults in France are affected today. This is the result of changes in lifestyles - we live more indoors than before - but not only that, as engineer Samuel Monnier, from the RNSA, explained to us . In cities in particular, " we have planted massive amounts of birch and plane trees: these are trees whose pollen is very aggressive," he explains. In other words, the development of crops with greater allergenic potential has largely contributed to the risk of becoming allergic.

Another characteristic of urban life is air pollution, which contributes to the intensification of allergy symptoms by irritating the respiratory tract and making people more susceptible to pollen allergies.

But not just to pollen: an individual who "becomes" sensitive to one allergen is in fact more likely to become so to others - and to develop one or more food allergies, for example.

The weather also plays a role: rain tends to "shove" pollen to the ground, providing a respite for allergy sufferers until the good weather returns. But beware... of thunderstorms : "During thunderstorms, the pollen concentration increases rapidly near the ground with strong downdrafts that carry grass pollen from the upper air layers to the air layers close to the ground," the RNSA indicated. Concretely, thunderstorms promote the bursting of pollen grains "into tiny, highly allergenic particles that penetrate deep into the lungs [...] Result: coughing, wheezing, difficulty breathing," which primarily threaten people with pollen allergies, but also asthmatics, young adults, and children.