pollen placed under close surveillance

Atmo Nouvelle-Aquitaine manages four other sensors in the region (Limoges, Angoulême, Niort and Poitiers), and monitors…

Atmo Nouvelle-Aquitaine manages four other sensors in the region (Limoges, Angoulême, Niort and Poitiers), and monitors these small seeds which can cause allergies in humans. Monitoring on behalf of the National Aerobiological Monitoring Network (RNSA) which is responsible for seven other points in New Aquitaine (Agen, Bordeaux, Périgueux, Mont-de-Marsan, Bayonne and Pau) i.e. one per department, and thus publishes every Friday, a map of France and therefore also a regional map of the risk of pollen allergy.


The sensor strip is cut into seven sequences representing what was harvested over the seven days of the week.

Xavier Léoty/ “South West”

The birch, the black beast

On this Monday morning, Nathalie Delaunay climbs the emergency ladder installed on the roof of the tax center. The sensor looks like a small weather vane. “It is. It turns with the wind, the air is sucked in and dust and particles stick to the strip, which turns on itself in a week”, underlines the specialist. Hence the need to keep an appointed day to change the drum that carries the tape. We get this precious witness back. We place a new one, close the weather vane and let it wiggle for another week.

Head to the Atmo site in Périgny, a few laps from La Rochelle. Nathalie Delaunay will count the pollen. She begins by retrieving the tape and cutting it into seven sections corresponding to the days of the week. “Hey, there, the sequence is a bit ocher. It was last Monday… the remnants of the Sahara sand. »

The pollens are more and more precocious, lengthening the period at risk of the sensitive and allergic people.

A small pink reagent heated beforehand makes it possible to stick the strip to the blades, coloring the pollen as it passes and leaving the dust in the dark. A coverslip to protect and we pass under the microscope. Nathalie wears a headset with a microphone. Here we go. She reads each of the seven lamellae aloud like a book and at a high rate: “Platanus, platanus, platanus, quercus, platanus, betula, fraxinus, platanus, platanus, unknown. »

The reading of the first slide was recorded with the Latin names of the pollens observed. “Platanus” for plane tree, “quercus” for oak, “betula” (birch) and “fraxinus” for ash. It recognizes varieties with the naked eye. “At least most of the time. Sometimes I have doubts. I then say “unknown” and will check in the catalog that the RSNA makes available to us with the characteristics of the pollens and their appearance. »

Nathalie Delaunay counts the pollen, slide by slide, reading the seeds like the sentences in a book.

Nathalie Delaunay counts the pollen, slide by slide, reading the seeds like the sentences in a book.

Xavier Léoty/ “South West”

Long live the rain

The exercise is over. It lasted a few minutes. The sequences of the week thus recorded are sent to the National Aerobiological Monitoring Network. “The dispatch must take place before Thursday evening so that the RSNA can publish its bulletin on Friday. A bulletin of allergic risks for the coming week, by city, with the four main pollens identified, which Atmo Nouvelle-Aquitaine also includes on its site. “The RNSA constructs this risk index, which ranges from 0 (zero) to 5 (high), based on counts but also on weather forecasts and clinical data from allergists. »

Last week, the pollen map of France was for the northern half and in particular for Charente-Maritime, colored red underlining the high risk reigning with birch, whose pollen is one of the most allergenic. “We are monitoring from January to October. In January, we are dealing with pollen from hazelnut trees, cypresses, poplars and ash trees. Currently, it is birch, the first grasses and urticaceae”, specifies Nathalie Delaunay who remarks that with global warming, pollens are increasingly precocious, lengthening the period at risk for sensitive and allergic people. . “This year, we had a real lack of rain, which leaves the pollen free to circulate. Because the rain flattens the offending little invisible seeds on the ground. She is expected this weekend. “The risk of allergy should not exceed the average level in the North”, announces the RSNA, unlike the South “where the pollens will be able to express themselves a little more freely with in particular plane tree pollens. »

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