Oxygen’s atomic structure makes it unstable. When oxygen is diatomized, it is stable as O2. Oxygen is one of the most common molecules in nature today, as it comprises about 21% of our air. Triatomic oxygen refers to ozone as having three oxygen atoms in its molecule.

At very high ozone concentrations, it is a light blue gas in contrast to oxygen. When present in low concentrations, ozone does not take on color. In addition to its distinctive odor, ozone has a pungent smell at higher levels. If diluted at low levels, ozone has a “clean” smell; in high concentrations, it has a much stronger odor. Naturally, ozone decomposes readily to oxygen. In addition to being a strong chemical oxidant, ozone is a highly reactive gas.

Half Life of Gaseous Ozone

According to the temperature, humidity, and movement of the ambient air, the time for half the ozone in air to decompose (half-life) varies from one hour to three days.

Gaseous Ozone
Half LIfe TimeTemperature
3-months-50-deg C
18-days-35-deg C
8-days-25-deg C
3-days20-deg C
1.5-hours120-deg C
1.5-seconds250-deg C

Half Life of Ozone Dissolved In Water

According to the temperature, PH, and water quality, the half-life of a compound in water is usually 30 minutes or less.

Dissolved in Water (pH 7)
Half Life TimeTemperature
30 Minutes15-deg C
20 Minutes20-deg C
15 Minutes25-deg C
12 Minutes30-deg C
8 Minutes35-deg C

No wall or other catalytic effects have been considered for these values based on thermal composition.

With organic loading, pressure, humidity, and other factors involved, the actual half-life of ozone is much, much shorter.  Ozone half-lives can be determined by these values, for example, by how quickly it decomposes, and also by how much temperature influences it.

Applications of ozone can be affected both positively and negatively by temperature.  The half-life of ozone is extremely long at very low temperatures, but ozone is much more stable and may not react as quickly.  Those temperatures may reduce the half-life of ozone, which may render it ineffective or speed up reaction rates, which can produce the desired reaction faster when temperatures are very high.