Lifestyles, climate, pollution… Why are there more people allergic to pollen than before?

Almost all of France is on average or even high vigilance for the risk of pollen allergies. Every year, more and more people are affected by these inconveniences.

In France, 20% of children over 9 years old and 30% of adults suffer from pollen allergies, the season of which is in full swing at the start of spring. And these numbers are increasing. According to the National Agency for Food, Environmental and Occupational Health Safety (ANSES), the number of people affected has tripled in thirty years.

Globally, the World Health Organization (WHO) estimates that half of the population will be affected by this type of allergy by 2050.

“Allergies are an early marker of changes in our environment”, analyzes for Pascal Demoly, pulmonologist-allergist at Montpellier University Hospital and president of the French Federation of Allergology.

If there are “many hypotheses” to explain this increase in the number of people allergic to pollen, Pascal Demoly firstly points to changes in our lifestyles, which affect our increased sensitivity.

“Allergies increase in developing countries when they ‘westernize'”, illustrates the specialist, citing in particular the example of the dislocation of the USSR.

“We thought there would be more allergies in East Germany due to the strong presence of industries,” he explains, “yet it was the opposite, but they have caught up with the rates Western countries in 10-15 years.

The reason: we spent on average more time outside before, and from then on, we became more sensitive to pollen. “It is generally our entire way of life” which is involved, deplores Pascal Demoly, citing the lack of physical activity, excess weight, loss of biodiversity, tobacco and even a diet poor in antioxidants.

Pollution exacerbates allergies

Air pollution is also an aggravating factor for pollen allergies, in particular “microparticle pollution”, including fine particles, which mainly come from wood heating, road traffic and construction site activities.

This pollution will tend to damage and fracture the pollen grains, which thus release more allergenic proteins. Additionally, because they are smaller, they penetrate deeper into the airways.

“The pollen is not at all the same in the city” as in the countryside. It appears “very damaged” and has a “completely deformed” wall, which makes it more allergenic, explained Samuel Monnier, engineer and spokesperson for the National Aerobiological Surveillance Network (RNSA), last spring.

In addition, the respiratory tract is more sensitive because it is irritated and weakened by pollution.

“Allergy patients are much more bothered by pollen in the presence of pollution,” says Pascal Demoly.

Thus, allergic people have more pronounced allergy attacks and more frequently develop asthma attacks, but also coughing fits or strong sneezing sequences.

Global warming

Also in question: global warming. Indeed, while temperatures are on average increasingly higher due to greenhouse gas emissions linked to human exploitation of fossil fuels, trees are flowering earlier. Thus, “the pollen season is lengthening”, comments Pascal Demoly. Due to the early heat, the risk of allergies occurred early this year.

Added to this is the increase in the concentration of carbon dioxide (CO2) in the atmosphere. The latter is necessary for photosynthesis in plants. When its rate increases, plants will produce more pollen.

A study has shown that ragweed, an invasive plant whose pollen is particularly allergenic, produces 131% more pollen than what it would have emitted in the 19th century before the industrial revolution. This could reach +320% by 2100. In the same way, the birch emits 20% more pollen than 30 years ago.

In addition, changes in temperature cause certain plant species to migrate to new areas. This is particularly the case for the ragweed mentioned above. “But at the same time other species will disappear,” says Pascal Demoly.

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