Your first steps: do not disturb it
The most important first step is simple: do not disturb it. Do not sand, scrape, drill, sweep, or try to remove or repair suspect material yourself, because that is often what releases dangerous fibers.
Next, avoid the area as much as you reasonably can if the material looks damaged or is shedding dust, and keep children and pets away from it. Do not vacuum or dry-sweep debris you think may contain asbestos.
Then report your concern to your landlord in writing — text, email, or a letter — describe the material and where it is, note any damage, and keep a copy. Ask the landlord to have it professionally tested and safely addressed.
If your landlord ignores damaged asbestos, you can also contact local code enforcement or health authorities, who may inspect and order action.
Because asbestos involves serious, long-term health risks, it is worth understanding your rights early. A free, confidential review can walk you through your options and what a landlord is required to do.
This is general information about California tenant rights, not legal advice. Every situation is different.