What “black mold” really means for tenants
"Black mold" usually refers to dark-colored molds — often a type called Stachybotrys — that grow in damp buildings. Reactions vary a lot from person to person, but mold indoors can affect health and should be taken seriously.
Black mold tends to grow where there is ongoing moisture: behind walls, under sinks, around leaks, and in poorly ventilated bathrooms. Its color alone does not tell you how harmful it is. What matters more is the amount of exposure and how sensitive each person is. Some people notice coughing, congestion, irritated eyes, or worsened asthma; others feel little at all.
The safest approach is to treat any significant indoor mold as a problem to fix rather than trying to guess about the exact species. Getting rid of the color on the surface is not the goal — stopping the moisture that feeds it is. If black mold appeared because your landlord left a leak unrepaired, a free review can explain your options.
This is general information about California tenant rights, not legal advice. Every situation is different.