If you rent your home, you are covered by the Residential Landlord-Tenant Act (RCW 59.18). Northwest Justice Project's Your rights as a tenant in Washington State explains residential tenants and landlords' rights and responsibilities in Washington.
Mold problems in buildings are a result of water and moisture problems. Renters need to operate the heating and ventilation systems to reduce water condensation. Renters need to notify landlords promptly, in writing, of any water leaks or moisture problems. If there is a water leak or moisture problem, it should be fixed by the landlord. Your local building and code enforcement official may take action if building problems are not addressed - they won't respond to mold complaints, so it's important to stress the source of the water problem.
Visit a list of resources for those seeking information regarding residential landlord/tenant issues.
Landlords are responsible for maintaining rental units, including fixing building problems such as water leaks and ventilation or heating defects which may lead to moisture problems. Landlords must notify their tenants about the health hazards associated with exposure to indoor mold and ways to control mold growth in their dwelling units. Posting this information in a visible, public location at the dwelling unit property is allowed.