Introduction

Background^1,2,3

Ozone is a chemical compound consisting of three oxygen atoms (O₃ – triatomic oxygen), a higher energetic form than normal atmospheric oxygen (O₂). Thus, the molecules of these two forms are different in structure (Figure 1).

It is one of the most important gases in the stratosphere due its ability to filter UV rays which is critical for the maintenance of biological balance in the biosphere. This protective layer can be seen as the blue-colored sky.

Figure 1. Oxygen and ozone formulas.

Ozone is produced naturally by the following natural methods:

• From electrical discharges following thunderstorms. Ozone is created when an oxygen molecule receives an electrical discharge breaking it into two oxygen atoms. The individual atoms combine with another oxygen molecule to form an O₃ molecule (Figure 2).
• From ultraviolet rays emitted from the sun which plays the role of electrical discharge over oxygen present in the stratosphere, thus, creating the ozone layer which absorbs most of the ultraviolet radiation emitted by the sun.

Figure 2. Production of ozone.

Medical grade ozone is made from pure medical oxygen because oxygen concentration in the atmospheric air is variable. Atmospheric air is made up of nitrogen (71%), oxygen (28%), and other gasses (1%) including ozone which is altered by processes related to altitude, temperature, and air pollution.

There are three different systems for generating ozone gas:

• Ultraviolet System: produces low concentrations of ozone. It is used in esthetics, saunas, and for air purification.
• Corona Discharge System: produces high concentrations of ozone. It is the most common system used in the medical/dental field. It is easy to handle and it has a controlled ozone production rate.
• Cold Plasma System: used in air and water purification.