Why are we increasingly exposed to pollen allergies?

In this month of June, the pollen allergy map in France is on red alert: all departments are experiencing peaks in indices, with the exception of Finistère. In the office of Dr. Audrey Gopal, allergist in Vincennes (Val-de-Marne), the schedule has also turned scarlet. “We have one appointment after another without respite. With, from the outset, patients suffering from more severe respiratory allergies,” testifies the practitioner.

In France, nearly one in three adults (and 20% of children over 9 years old) suffer from a pollen allergy. This figure has almost doubled in thirty years. Over the course of his long years of practice, allergist Philippe Poulain has seen “systematically multiple allergies” appear. The World Health Organization predicts that half of the world’s population will be affected by 2050.

Long trend

Certainly, each year, respiratory pathologies awaken in spring: trees between April and May, then grasses (herbaceous plants with bucolic names such as timothy, bluegrass, ryegrass, fescue, rye, oats, etc.) between June and July. This year, a spring with mild temperatures combined with regular precipitation favored the growth of grasses.

But this clear upsurge corresponds to a long-term trend. Two major parameters are involved in allergies: our personal genetic background, as well as our environment. Climate change, by causing an overall rise in temperatures, leads to longer pollination periods. Ashes, cypresses and birches, which traditionally opened the allergy season, are now flowering earlier and earlier. These higher temperatures also lead certain exotic plants to move closer to our latitudes. Thus ragweed, “an extremely allergenic plant from the United States”, describes Dr Poulain. “Originally present in the Rhône corridor, it is in the process of colonizing the entire territory, prolonging allergic reactions in August and September,” he continues.

Pollution, for its part, irritates and weakens the respiratory tract, which allows pollen to penetrate deeper into the body. In addition, a high concentration of carbon dioxide in the air causes it to release more allergens. Urban pollens thus prove to be more irritating than their rural cousins.

Third factor, more surprising this one: our progress in terms of hygiene. As our organisms are now better protected from microbes and “they no longer live in the countryside and in the open air, they are less accustomed to considering certain bacteria as harmless,” explains Dr. Poulain. In short, “our lifestyles have not finished making the summer season that of rhinitis and asthma,” notes the doctor philosophically.