Despite what you may
have heard, ozone is not a
miracle product that cures everything from warts to
hang nails. It is a gas that can supplement the
cleaning and deodorisation process when used
responsibly with other cleaning methods.
Ozone is a strong oxidising agent that chemically
reacts with other substances (like odours), to
chemically change them to non-odorous byproducts.
Ozone will kill microorganisms when
high enough concentrations exist. Microorganisms
can cause odours and ozone can therefore be
effective against both the odours and the source of
What about ozone generators?
Ozone generators produce ozone. Brand ‘A’
produces the same ozone as Brand ‘B’. The
differences in ozone generators are essentially the
way they produce ozone, the amount of ozone they
produce and the bells and whistles built into the
equipment. It is these variables that drive
recommendations regarding which unit should be
used for which application.
The smaller the ozone output, the smaller the
area the unit will effectively treat in a timely manner
and vice versa. Options like timers, output controls,
hoses, etc. are all designed to make units more
attractive to specific markets or applications. The
truth is most units can be made to work effectively
in most environments. The differences among them
can make them more convenient to use, or work
Advantages of ozone
• Ozone may well be the only deodorising product
useable when the customer suffers from severe cleaning of
metal screens, ceramic insulators
and filter media.
• Ozone works on a molecular basis. With proper
encouragement (air thrust) it can penetrate into
minute cracks and crevices that may be
impenetrable by chemical deodorants.
What is ozone?
Ozone, a three-atom form of oxygen, is a normal
trace element in the earth’s atmosphere. Ozone is
the strongest commercially available oxidising
agent. Because gaseous ozone is highly reactive, it
readily oxidises organic matter and has a variety of
uses such as a bactericide and an algaecide. The life
cycle of ozone is: generation, oxidation, decay. Its
presence can be detected by its odour at very low
How is ozone produced?
Ozone may be produced in three ways:
1 Nature creates ozone by solar radiation
oxygen in the atmosphere at high altitudes, in
the Arctic and over snow-covered terrain.
The air we breath contains a small amount
2 Ozone may also be produced by electrical
discharges. Nature creates ozone, which
purifies the air, by electrical discharges or
simply by air-to-air lightning and air-to-surface
lightning. In other words, ozone is created by an
electrical discharge in an air space. Ozone is also
produced by vacuum cleaners, copying machines,
electric trains, some shop tools, electrostatic
precipitation, other appliances and ozone
3 Ozone is also formed when hydrocarbons
nitrogen oxides react with each other in the
presence of sunlight. Contributing to this method
of ozone production are: automobiles, industrial
emissions from smokestacks, oil wells, petrol
stations and refineries, dry cleaning plants,
chemical plants, etc. When these chemicals form
ozone by photosynthesis, the result is often a
major component of ‘smog’. Thus ozone can be
both an oxidant and an irritant depending on its
chemical make-up, or its quantity and quality.
Why use ozone?
Ozone is a form of oxygen which has been
electrically energised. The energy makes ozone
more chemically active than oxygen. Most
odoriferous substances are described by chemists
as unsaturated. Unsaturated means their molecular
chemical sensitivity. Most
all chemicals used in
deodorisation will leave some residue in the air or
on surfaces. These residues can produce severe
reactions from those who are highly sensitive to
chemicals. Ozone, on the other hand dissipates
completely within minutes (the crisp smell left in
the air is usually attributed to the absence of
normal odours) and leaves no lingering residue
to upset sensitive persons.
• Home owners complain about objectionably
strong fragrances left by some deodorising
chemicals, ozone may be used to correct that
situation within a short period of time.
• Moisture sensitive surfaces and fabrics that
require deodorising can be treated by ozone
(exceptions are elastic and leather). Clothing,
draperies, books, paintings and unfinished wood
can effectively be deodorised using ozone
• Because ozone gas employs the principle of
oxidation (a chemical reaction) once the odour is
gone, the result is permanent.
• Water infiltration situations which create odour
generated by microorganisms on unfinished
wood, in basements or on interior wall wood,
insulation or drywall, may be effectively treated
using ozone. Ozone can penetrate complex
structural surfaces and destroy odour producing
microorganisms at their source. In low
concentrations ozone can control the germination
of mould and mildew spores while drying takes
place. (This procedure should only be used by the
cleaning and restoration specialist.)
• Other than the initial investment, there is
little cost involved in operating ozone units,
and maintenance involves only a periodic structure is
not closed and will readily combine with
oxygen. Ozone actually breaks down odour-causing
molecules such as hydrocarbons (HC) into water
vapour (H2O) and carbon dioxide (CO2). An ozone
generator does not mask odours with perfume or
chemicals, it oxidises (changes the substance of)
How much is needed?
Ozone will oxidise at a level one-eighth of the limit
established by the American Conference of
Governmental Industrial Hygienists. Ozone will
function, even at this very low level. When the
ozone demand is reduced, that is, odours have been
oxidised, the residual ozone will decay to oxygen.
The decay rate is a function of temperature: the
warmer the faster the decay rates, and the colder the
slower the rate.
Is ozone safe?
Several organisations have established limits for
ozone measured in parts per million (ppm).
Before we proceed, a review of the size of the
ozone concentration will help grasp ‘a small
amount of ozone’. One part in one million parts
is the same magnitude as one inch in sixteen
miles, or one ounce of sand in over three tons of
cement. The human irritation threshold appears
to be about 0.05 ppm, with no evidence of health
damage by continuous exposure to lower
The following ppm values apply:
0.12 Environment Protection Agency for
city, out of doors air quality.
0.10 American Conference of
Governmental Industrial Hygienists
Limit for exposure for
8 hours a day with no side effects.
0.05 Food and Drug Administration limit
for ozone generator labelled as a
medical device. This value is often
used by other organisations, for
example, Underwriters Laboratory
(UL) used this value for electrostatic
precipitators ozone limit.
0.03 to 0.06 Value frequently measured in
0.010 to 0.015 Odour threshold for most
0.005 to 0.01 Value measured in fresh country
A review of medical literature indicates caution
must be exercised when exposed to 0.3ppm to
0.5ppm for even short periods of time. n