Wearing a regular mask will not help against bleach. Bleach has chlorine gas, and the molecules are smaller than the pores in the mask. Masks only work for dust, bacteria...For chemicals, you would need a vapor breathing mask, like the one they use in the movies. Just dilute the bleach with water, so it will not evaporate fast, and try to work in a ventilated area. Also, a rule of thumb with working with chemical (not all of them, but most), your baby will be safe if you are safe...if you feel nauseated or get a headache that's bad for your baby...if you don't feel anything you should be fine. As I said, this is very general and it does not work with some chemicals like methanol....just ve careful, and don't trust the mask! It does not work with vapours!
I usually just wear a mask and gloves when cleaning with bleach and have had no problems