Allergy warning: several areas of France on red alert for ragweed pollen

Warnings have been raised in central and south-west France over the presence of ragweed (ambroisie) pollen.

The national pollen watchdog (Réseau National de Surveillance Aérobiologique, RNSA) has placed 12 departments on a red alert, the highest possible, over pollen levels from the plant.

The departments are: 

• Creuse

• Allier

• Nièvre

• Saône-et-Loire

• Loire

• Rhône

• Ain

• Isère

• Drôme

• Ardèche

• Gard

• Vaucluse

Elsewhere, yellow-tier warnings are in place across the south-west for ragweed pollen.

It is particularly potent for those who suffer an allergy, and each plant can produce up to a billion pollen grains annually.

In the north, a low to medium presence of a number of other common pollens (grass, mugwort, nettles) has raised overall warning levels. 

Warm and sunny weather in the Rhône Valley, coupled with the wind levels, will cause the pollen to spread widely throughout the weekend.

Read more: Weather in France August 26 – August 30: Forecast by area this week

Up to 3.5 million allergic to ragweed pollen 

Estimates from the French Agency for Food, Environmental and Occupational Health and Safety (Anses) state that between one and 3.5 million people in France are allergic to ragweed in the country. 

The plant comes in around 40 species, and was imported from North America in the 1800s. It has since become common across Europe, particularly in France, where conditions are ideal for ragweed to proliferate. 

It is sometimes classed as an invasive species in Europe.

The most common form of ragweed grows as a bush, and reaches around one metre high. It has green leaves with small flowers, and a reddish stem. It is common across the countryside in rural areas, as well as some urban landscapes. 

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