Little bit of mould.

[GUS.K]

Called out to an electrical fault job today and when investigating the issue, opened the bathroom door and was confronted by this. The owner still uses this bathroom every day, she is frail and sick. I mentioned how dangerous this is and she didn't seem too worried, said she'll get it looked at one day soon.

[LewisM]

Studied mycotoxins among other things in my B.Sc (Microbiology, minor Medical Microbiology) and recent research shows that black mold toxicity is more mythical than factual.



Some light reading: https://link.springer.com/article/10.1007/s12016-017-8601-z

Still, she needs that GONE regardless. Sodium Hypochlorite will get rid of it quickly and keep it at bay for a good while.

[GUS.K]

Surely breathing that in long term can't be healthy for anyone.

[Constant]

Lately I've been applying some time and effort aimed at reducing damp and mould in and about the house, in particular, the converted garage where the optical gear is stored.
It's surprising how effective these measures have been, "garage smells" and a noticeable reduction in dust. I'm running a large filter used in woodworking shops that reduces particulates (300 microns)
The net effect of this investment is safer storage for my expensive optical/photographic gear. A huge bonus, the place feels clean, just as a clean room has filtered dehumidified air so does my "garage", the air feels "light" and clean and conducive to work.
Such has been the success of the project Im going to "double down" and make the entire downstairs area of my house into a clean room of sorts. Clearly I won't get anywhere near a clean room as there's multiple door and window openings. It's a very interesting experiment-project.
The dividends have been so apparent that even SOMBO is 100% on-board!
If you're interested I can take some pics

[multiweb]

:eyepop: This thing is alive. Looks like the grudge.

[Sunfish]

The owner probably has very poor vision and cannot see how bad it looks.

[taminga16]

Ivan, contact the local government authority, they may be able to assist with the problem and ease your concerns.
Greg.