How long can pet dander stay in the air?

4 months. The available information is for cat dander, but dog is probably similar. Typically about 4 months is needed to decrease levels to below 8 microgram/gram carpet dust. It is possible for levels to persist longer.
Hours. That's why if you are allergic to cats or dogs you should keep them out of the bedroom 100% of the time. If that is impossible, a hepa air filter may help. Also check out other tips at www acaai.Org.