NABAS deployment of ozone is very safe. During operation, there is no detectable trace of ozone in the air as NABAS delivery of ozone to water is by way of >95% of <5 micron bubbles, achieving >95% dissolution of ozone in water. This cannot be said of other technologies where most of the bubbles are >20 microns which expands and rise to the surface, releasing ozone outside the water. For indoor operation, once the ozone disinfects the water with nothing to eradiate, you will begin to smell ozone in the air at which time, the ozone generator is turned off, running only the oxygen as needed. For outdoor operation in a large body of water, there is no concern for ozone escapement.