If there was water damage and mold or mildew in a unit I was renting for a few years and the landlord had taken no action I would have moved.
I do not pay for rent for an apartment, that I consider damaged.
Why are you still there?
In most cases you would not have mold, in your rental unit. There are only about 1-2 mold that would be of medical harm to you. You would have mildew in your rental unit. There are commercial and home remedies you may use to cure this mildew.
You would be able to purchase the commercial brands at your local hardware stores. You are able to google for a home remedy in the cure of mildew. Normally warm sudsy water with vinegar would do the job.
If you would want to see what you are able to do about this situation, you would need to google the local landlord/tenant agency, followed by the city and state in which you reside. This agency would normally offer information about about rental problems at not cost to you.
You might also want to check out the state website to see if there is information you are able to use and perhaps remedy.
If you consider this a health and safety issue, you might want to contact the city Department of Health and Safety Department and make a complaint with them.
I hope this has been of some benefit to you, good luck.