See RCW 59.18.07 and 59.18.090. If you give written notice to the landlord and he or she fails to remedy within a certain time, then you can move out and terminate the lease. If the landlord has fixed the problem already, then your choices are a bit more limited. RCW 59.18.120 says that you can terminate the tenancy if you convince an arbitrator that the mold problem is too severe to remedy. Either way though, you are going to have to show that the mold is still a problem before you can use it as an excuse to break the lease.