For more than a decade, Martinique has been living under the cyclical threat of Sargassum. But the 2025–2026 off-season broke with tradition: unlike in previous years, the so-called «off-season» was marked by early and regular strandings—albeit of low intensity—limiting the respite period usually observed. This now virtually permanent phenomenon is taking a heavy toll on the health of residents along the Atlantic coast and has mobilized all of Martinique’s institutions.
A monitoring system that is unique in France
In light of this reality, the ARS and Madininair have collaborated to deploy a network of sensors to measure hydrogen sulfide (H₂S) in the main affected areas, with the aim of continuously monitoring concentrations of this gas, which is produced by the decomposition of algae. Established in 2015, this operational network of 20 autonomous devices is the first of its kind in France, made possible thanks to financial support from ADEME, CTM, ARS, Espace Sud, and Cap Nord.
At the same time, Madininair and Gwad’Air have joined forces with IMT Nord Europe on the Sarg’Ex project, which aims to find practical solutions to limit exposure to harmful emissions in naturally ventilated buildings. This multi-year project includes field surveys, experimental tests, and public awareness campaigns for residents.
The School Crisis in Le Robert: A Sign of an Urgent Problem
The year 2025 brought the gravity of the situation into sharp focus. In April 2025, the CTM and the ARS formed an Independent Committee of Experts, coordinated by Professor Dabor Resiere, a toxicologist and intensive care physician at the Martinique University Hospital, to assess the health impacts of the recurring strandings, particularly in the town of Le Robert, where Robert 3 Middle School has been closed on several occasions.
In response to the mobilization of local residents, the elected officials of the Martinique Assembly voted, during a plenary session on January 29, 2026, in favor of a health support program for vulnerable populations, including temporary shelter for pregnant women and the elderly at sites not exposed to the fumes. A request to declare a public health emergency was also submitted to lawmakers.
Toward a Structural Solution
The 2025–2026 off-season confirms that Sargassum is no longer a seasonal phenomenon but a permanent environmental reality. Strandings were observed in the West Indies as early as mid-November 2025, with a frequency and persistence unusual for this time of year. Forecasts from Météo-France Martinique indicate a persistent risk of sargassum strandings along the entire Atlantic coastline in the coming weeks.
GIP Sargasses, the sole operator created in 2023 by the French government, the CTM, and the territory’s three EPCIs, now coordinates collection operations both on land and at sea. Additional funding of 900,000 euros was secured in 2025 to strengthen these efforts. The DEAL Martinique has also launched a 2026 call for community projects that specifically includes combating the proliferation of Sargassum among its priority areas.
In short:
Sargassum is no longer a seasonal phenomenon but a permanent environmental reality in Martinique. Institutional measures are being strengthened—air monitoring, scientific expertise, the CTM action plan—but communities in the North Atlantic are calling for sustainable, structural solutions that go far beyond emergency measures.
