Generality
Ozone is a molecule made up of three oxygen atoms (its molecular formula is O
3
).
It has a characteristic pungent odor (the same that sometimes accompanies thunderstorms due to the
ozone produced by electrical discharges of lightning). Its name derives from the Greek "ozein" which
means "smell".
It has a light blue color and is a much more energetic oxidant than oxygen. It is an essential gas for life
on Earth: in nature, ozone exists in the upper layers of the atmosphere and is particularly important
because it absorbs ultraviolet light (highly energetic and harmful) acting as a screen to prevent these
radiation from reaching the earth's surface.
It is able to react with organic substances with double bonds: this characteristic is used in many water
and air treatment processes. Its bactericidal, fungicidal and inactivating effect of viruses has long been
known.
In Italy, in July 1996 with protocol no. 24482, the Ministry of Health recognized ozone as a "NATURAL
PRESIDIUM FOR STERILIZATION OF ENVIRONMENTS".
Ozone is an unstable gas and spontaneously decays to oxygen. The time required for ozone decay,
depending on temperature, humidity and chemical and biological contamination, and always depends on
the concentrations of use.
Effects on humans
Ozone is an irritating gas for the respiratory tract. It is possible to detect its acrid odor already at a
concentration between 0.008 ppm and 0.02 ppm. The smell however is not a reliable index of the
concentration of ozone in the air due to habituation phenomena. Therefore, operators who frequently use
air ozonators must have appropriate detectors.
At concentrations of 0.1 ppm in the air, ozone acts on the mucous membrane, causing irritation of the
nose, throat, eyes and dry cough. The most sensitive people (elderly, asthmatic subjects, etc.) can be
subject to asthma attacks even at low ozone concentrations.
At concentrations of 1 ppm headache, chest pain and severe trachea irritation occur.
High concentrations of ozone can cause coma and death.
OZONE
F
G
7
00
/O
Z
3.
5
F
G
7
0
2
/O
Z
3.
5
