It's not good to breathe the Breton air this week. Combined with anticyclonic weather conditions, the cold wave currently affecting Brittany has led to a sharp deterioration in air quality. From Sunday January 12, Ille-et-Vilaine was affected by an alert for fine particles of less than 2.5 micrometers (PM2.5) due to exceeding the recommendation thresholds. The alert was extended to Morbihan and Côtes-d'Armor this Tuesday.
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1 Why is air quality significantly degraded?
“There is a sharp increase in the rate of fine particles in the atmosphere linked to the use of inefficient wood heating,” indicates Gaël Lefeuvre, director of the specialized association Air Breizh. “When people light the fireplaces in the evening, it’s horror.” Road traffic and certain industrial activities are also responsible for part of the release of fine particles.
Why are fine particles dangerous for health?
Due to its extremely small diameter, PM 2.5 penetrates deep into the body and can impair respiratory function. Published by Public Health France in 2021, a report states that fine particle pollution is responsible for 40,000 premature deaths in the country each year, or 7% of annual mortality.
In Rennes, certain measuring stations are causing the meters to panic. In particular, 62 micrograms (µg) per cubic meter were measured in the city center at 10 p.m. this Monday evening… more than four times the recommendation threshold defined by the WHO.
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2 How long will the episode last?
In the absence of wind, particles continue to accumulate in the lower layers of the atmosphere. And this is not likely to get better in the days to come. “We are in a situation of anticyclonic blocking,” indicates Sébastien Decaux of Météo Bretagne. “As long as it doesn't rain, the air quality will not improve. A disturbance could arrive on Sunday from the west, but I am afraid that the situation will not really improve before the middle of next week.
-Faced with this episode of pollution which is likely to last, certain measures have already been taken locally to try to limit the consequences of the deterioration in air quality. In Ille-et-Vilaine, the Prefecture has notably decided to lower the maximum speed by 20 km/h on all expressways in the department to reduce emissions linked to cars. In Rennes, the STAR network had already deployed its air quality pass at a reduced price from Monday in order to encourage residents to use public transport.
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3 What are the recommendations to follow?
In these conditions, it is recommended to avoid practicing physical activity outdoors for the days to come. “Even if there are a few kilos to lose after the holidays, this is not the week to go jogging,” breathes Gaël Lefeuvre. “You should know that we inhale 6 to 7 times more air when running than when we are resting. Given the levels of fine particles this week, this is really not recommended. We're not just talking about vulnerable people. It can even have long-term consequences for healthy people.” As long as the pollution alert is in effect, it is better to favor shorter outings or ones that require less effort.
“It is appropriate to maintain the usual ventilation and aeration practices and not to aggravate the effects of this pollution by exposing oneself to additional irritating factors: tobacco smoke, use of solvents indoors, heating with wood,” also writes Air Breizh in its latest bulletin. Finally, in the event of respiratory or cardiac discomfort, do not hesitate to contact a healthcare professional immediately.
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