DO NOT USE BLEACH! I know common wisdom says use bleach, but what this does is add to the crap already in the air in addition to possible mold spores. Use a vinegar water solution, then soap & water. I talked to several drs & also ppl who clean after floods & such because we had this problem in our home too. Older homes w/o adequate ventilation in bathrooms often do. Make sure u open a window & or leave the door ajar during & after yr shower. Good luck & don't forget the face mask )
To clean black mold in a tub shower, first put on a face mask before entering the bathroom. Then, use a hair dryer that is on high heat directly to the mold for about 5 minutes. You will the spray the whole tub area with either vinegar or bleach. Visit http://www.ehow.com/how_4880750_clean-black-mold-tub.html for details.