• Sensors have been installed in the bay of Saint-Brieuc to measure air quality.

  • The measurements should make it possible to determine the levels of hydrogen sulphide concentration in the bay, invaded by green algae.

  • The indicators appear more pupil than in 2020 on a site in Hillion.

What is the level of air pollution in the bay of Saint-Brieuc (Côtes-d'Armor) where green algae proliferate? To find out, sensors for hydrogen sulfide (H2S), the toxic gas released by decaying green algae, have been installed near four sites in the bay to measure air quality, a-t- we learned from the Regional Health Agency (ARS).

"In order to characterize the concentration levels of this gas near coastal sectors affected by the phenomenon of stranding of green algae, at the initiative of Saint-Brieuc Armor Agglomeration, and in partnership with ARS Bretagne, campaigns of measurement of hydrogen sulphide in the air are carried out by the Air Breizh Association ", indicated the ARS of Brittany after the report of

Special Envoy

broadcast on Thursday, in which residents complain in particular of headaches.

Indicators higher than in 2020 at a site in Hillion

The choice of locations for the sensors was dictated by "recurring algae deposits, difficult access for their collection, proximity to homes and public attendance," said ARS. "These studies aim to improve knowledge of environmental data on sites affected by deposits of green algae and to identify the conditions leading to a possible deterioration of air quality," he said. -she adds.

The 2021 measurement campaign, which started on May 4, shows higher indicators on one of the sites (L'Hôtellerie à Hillion) than in 2020 with a one-time exceeding of the WHO guideline value on the 29th and 20th. June 30 (201 and 153 micrograms per cubic meter, respectively).

“On this same site, from May 4 to July 15, the average readings over this period is 20.4 micrograms per cubic meter.

And no exceedance has been noted since, ”continues the ARS.

Monitoring of measures until September 30

The health reference defined by the WHO is 150 micrograms per cubic meter over twenty-four hours (daily average), a "concentration based on the occurrence of the first local irritant effects of hydrogen sulfide in the eye".

“Although the levels of H2S concentration measured at the Hôtel de l'Hôtellerie remain well below the toxicity thresholds both in terms of their level and in terms of their duration, it seemed relevant to us (…) to complete this system of study carried out by health professionals in Saint Brieuc Agglomeration, ”adds the ARS.

Monitoring of measures at these four sites will continue until September 30, 2021.

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  • Air quality

  • Green algae

  • Algae

  • Planet