Ozone consists of three adjoined oxygen atoms, and is therefore referred to as O3, in the same way that oxygen (O2) consists of two oxygen atoms. Ozone is not very prominent in our atmosphere yet it plays a vital role in our day-to-day lives. It is invisible although when concentrated enough it takes on a blue tinge.
The noise you may notice is the fan(s), the only moving parts in an ozone generator. Their job is to suck oxygen in to create the ozone, and to help propel the ozone as high as possible. Because ozone is heavier than air, it needs to reach a decent height in order for it to be effective at removing pollutants in the air.
In order to maintain a constant level of clean air, it is important to run an ozone generator on a regular basis. Simply implement it into your existing cleaning procedures to cause as little disturbance to your day as possible.