Indoor Humidity Levels: What Range to Aim For
Why indoor humidity matters for your home, the range public agencies suggest, and how to manage humidity in Bay Area microclimates.
This guide is general information, not medical advice. If you have health concerns, please consult a medical professional.
Why humidity matters
Humidity affects comfort, building materials and how easily mold can grow. Persistent high humidity allows moisture to collect on cool surfaces such as windows and exterior walls.
The suggested range
The EPA suggests keeping indoor relative humidity below 60%, ideally between 30% and 50%. Short spikes after showers or cooking are normal; sustained high readings are worth attention.
Managing humidity
Run exhaust fans during and after showers and cooking, vent dryers outdoors, fix leaks, and consider a dehumidifier in damp rooms or crawlspaces. In coastal fog belts, ventilation and air circulation are especially helpful.
Room-by-room readings over several visits show where humidity is consistently higher than elsewhere.
Want measured information about your home?
AirCare 365 provides humidity and mold and indoor air quality testing across the Bay Area.
Sources
Serving San Francisco, San Mateo, Menlo Park, San Jose, Sunnyvale, Palo Alto, Oakland, Fremont and the rest of the Bay Area.