General Discussion

A number of people, a horse, and a number of wild boars have died or been hospitalized in a part of France where huge blooms of seaweed had washed ashore and begun to rot. The Guardian published a very extensive, in-depth article on the situation: https://www.theguardian.com/news/2026/may/12/i-couldnt-breathe-the-sinister-spread-of-frances-killer-seaweed

Lots more articles online: https://www.google.com/search?q=hydrogen+sulfide+from+rotting+seaweed+claims+lives&udm=14

Above concentrations of 50ppm*, H2S has a way of "numbing" the sense of smell, which makes it possible for people to fail to notice how intense the smell is, after an initial exposure. H2S has an offensive, rotten egg smell (rotting eggs produce H2S) which is detectable at very low, non-hazardous levels (as low as 0.05 ppm*), but after a while, it just isn't repulsive enough to keep people away, and they can breathe in a substantial dose without being aware of it, until they wake up in the ambulance or hospital -- IF they're lucky.

* marks info from the Guardian article, which is very informative, but which can't be copied !! Please see the article https://www.theguardian.com/news/2026/may/12/i-couldnt-breathe-the-sinister-spread-of-frances-killer-seaweed