The pollen season is open. Weather conditions obviously have an impact on the production, release and dispersal of pollen grains. Here are the most problematic phenomena for allergy sufferers.
Spring has finally set in and with it, longer days, more intense sunshine, gradually rising temperatures and… the pollens that are also making their comeback ! These microscopic grains (between 20 and 30 microns) released by flowering plants to allow them to reproduce, ruin the lives of nearly 20% of adults and 30% of children. Allergies that manifest themselves with several symptoms: stuffy or runny nose, swelling of the eyelids, watery eyes, tingling of the throat and ears, repeated sneezing and headaches… To better inform about their outbreak and location, the National Aerobiological Monitoring Network regularly updates its pollen vigilance map.
Blame it on the weather? Not only! It is above all a disruption of the immune system which corresponds to a loss of tolerance vis-à-vis substances that are a priori harmless: allergens. If the weather were solely responsible for these ailments, we would obviously all suffer from allergies. For the allergy to be triggered, two conditions are necessary: a genetic predisposition, an exposure to the allergenic substance. Allergy is therefore not a deficit or an insufficiency of immunity, it is on the contrary an exaggerated immune defense reaction.
However, certain weather conditions are indeed much more favorable to an explosion of pollen at this time of year.
Sunny and mild weather
This is undoubtedly the most pleasant time for the mind but the most difficult for those with allergies: the greater sunshine at this time of year favors the triggering of pollination. The predominantly anticyclonic conditions favor the abundant emission of pollen into the air. In addition to the sun, the mildness of spring accelerates the development of plants and also triggers earlier pollination of certain species. As well, a high thermal amplitude during a day (typical phenomenon in spring) also contributes to accentuate the release of pollen.
It is obviously recommended to take precautions when the weather is sunny and mild if you want to go for a walk in the fresh air.
storms and wind
People with allergies should also avoid going out after a storm., a phenomenon also very present in the spring. Storms also weaken the grains that produce the proteins causing allergies. Heavy rain throws pollen on the ground and breaks it up into allergenic particles. These particles are not stopped by our eyelashes and nasal mucous membranes. They then penetrate more easily to our bronchi.
Also, increases in asthma attacks have been episodically described in several countries during periods of pollen emission, in particular following a storm. These phenomena are poorly documented in France, but one of them, which occurred in Nantes on June 7, 2013, particularly attracted the attention of French researchers, who warn people allergic to pollen. That day, a sharp increase in calls to SOS Médecins Nantes for asthma attacks was observed from 9 p.m., followed by a peak at midnight.
At last, the wind also plays a decisive role in the transport of pollen over long distances. The Autan wind, sometimes strong in the south, can move pollen to other departments. Finally, gusts of wind can exacerbate the symptoms of conjunctivitis in allergy sufferers, thus warns the RNSA.
Pollution is also an aggravating factor. The polluting substances present in the air weaken the wall of the pollen grains, which more easily release the pollen proteins responsible for allergies. In addition, pollution aggravates allergic reactions. Indeed, pollutants irritate the respiratory system and the eyes, which become more susceptible to allergic conditions. The level of pollution also has a link with the weather: in anticyclonic weather, the presence of high pressure presses the pollen close to the ground and the absence of wind prevents their dispersion.
Wet and cooler weather
the best weather for an allergy sufferer therefore remains humid conditionss. In rainy weather the plant retains its pollen to release it under more favorable conditions and continuous but light to moderate rains flatten the pollen to the ground.
Also the climate is also important: if the winter was rather mild, it allows an early spring and a greater release of pollen. On the other hand, if the winter was cold, with numerous episodes of frost, pollination is delayed.
And as a reminder, simple gestures can help fight against allergies: wearing a protective mask against Covid-19 (which would prove to be relatively effective as a barrier against pollen), rinsing your hair in the evening, ventilating the rooms preferably before sunrise and after sunset, or avoid outdoor activities that lead to overexposure to pollen.
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