Time is needed to destroy all odor-causing molecules. Length of time is determined by the degree of odor. Sometimes, it might take a few days before you notice the difference. For major odors, ozone is not a weekend warrior. Some of the smell may return after a short period without it.
Activated oxygen is best-used full time at constant and natural ambient levels.
Smoke smells from fire damage will require higher concentration levels. Activated oxygen is used to counteract any objectionable odor that might arise. It maintains the air in a fresh, odorless condition. The air in the room contains a fresh pleasant odor and musty smells are controlled when using O3 at relative low natural concentrations. It has been very successful in permanent deodorizing when used the proper way.