| The ordinary man on the street has probably learned
through the media and popular misinformation that
ozone is something toxic in the air. It is supposed
to be a real health hazard and major pollutant to be
avoided. In fact, when most people think of air
pollution, they often think of ozone levels and relate
the two directly. Therefore, just the concept of ozone
as a purifying agent would be an apparent contradiction
in terms. But the contradiction is only ‘apparent’ for
there is in practice, no safer, effective and more
convenient oxidizing agent (acting alone) to purify
polluted air, than this very natural element!
Moreover, it is in part, nature’s way of cleaning the
air! As the saying goes, ‘ fire can kill, fire can also
help’ depending on how you use it. Just as it does naturally outdoors, ozone does have
a great potential for improving indoor air quality under
the right conditions.
The Nature’s Way of Cleaning the Environment
Ozone is a molecule composed of three atoms of
oxygen. Pure ozone is produced naturally and has a
distinctly pale blue colour when it is isolated as a
crystalline solid or liquid at very low temperatures.
When it is generated commercially from the air, a
colourless gas is produced. At low concentrations,
it has a very distinct sweet and pleasant odour –
which has at times been referred to as the smell
of ‘fresh, clean air’ as ‘in the mountains’ and
‘near waterfalls’, or ‘after a thunderstorm or lightning’.
Natural ozone concentration at ground level can
vary between 0.01 – 0.05 ppm. Ozone is the second most
powerful oxidizing agent in the world. It is second only
to fluorine which itself finds very limited use in practice,
since the latter is a rare and expensive halogen gas
that has many devastating side effects and complications
for routine human applications. Ozone works at killing
bacteria more than 1,000 times faster than chlorine.
Some History
Ozone was discovered in 1840 by a German chemist
but its utilization in industrial situations has a rather long
and impressive history. This was way before the current
environment concerns put it on the scientific center stage.
The most common use of ozone to date is probably in
the treatment of water for drinking. In 1906, a group of
scientists and doctors studied the ozonation system at the
Outshoorn plant in Holland and later constructed a plant
in Nice, France capable of handling 19,000 cubic meters
per day, using ozonation for disinfection. For this reason,
Nice is considered to be ‘the birthplace’ of ozonation for
drinking water treatment. Today that has become a
widespread practice, in many parts of the world.Ozone
was first used on meats in 1909 in Cologne, France – ironically, by German scientists. The US Department
of Agriculture was slow to acknowledge and approve its
use in foods but after many decades, they have now ‘seen
the light’! This has really been long in coming since an
application of ozone use was first published in the United
States in 1885.
It is now widely used as an oxidizing, deodorizing, sterilizing
and bleaching agent. As powerful an oxidizing and sterilizing
agent as ozone is, the remarkable property is that it decomposes
to a non-toxic, environmentally safe material. This is in clear
contrast to chlorine which produces hypochlorous and hydrochloric
acid. Even in its widespread use in water, chlorine has
complications of odour, taste, allergies and irritation for sensitive
individuals. In considering the history of ozone, perhaps it is appropriate to
include a reference to a series of studies published at the height
of the Cold War in the Journal Priroda (1976) where the
Department of Health in Russia established some important
points concerning the use of ozone in closed indoor environments.
They found that normal air loses its basic ‘freshness’ quality
when it was drawn into air conditioning and heating systems,
with a loss of as much as 90% of its ozone and ion levels.
This was demonstrated to cause symptoms for building
occupants who complained of headaches, weakness
and a general poor feeling – commonly referred to as
‘sick building syndrome’. However, after five months of testing,
with both a test group and a control group, the subsequent
exposure to 15ppb (parts per billion, a level not so atypical
of normal air) of ozone, restored a feeling of well being.
Moreover, at these levels of exposure, they were able
to observe increase immune potential, higher oxygen
content in the blood, improved blood pressure readings,
and the reduction of many stress characteristics associated
with working in modern office environments. Studies
by the Institute of Child and Adolescent Hygiene
showed that by raising the ozone levels in classrooms to
15ppb, up to 69% of the students decreased the time required
to complete concentration tasks. They also noted favourable
changes in respiration, mental reserve capacities and
general state of physical and mental health.
Ozone Power
In the area of public health, ozone technology has been
a potential source fir reducing the role of infection, both
in the home and in healthcare facilities. Ozone is a
powerful, broad-spectrum antimicrobial agent that has
been found to be effective against bacteria, fungi, viruses,
protozoa, bacterial and fungal spores. Potential applications
for ozone in the food industry include:- increasing yield of
certain crops, protecting raw agricultural commodities
during storage and transit, sanitizing packaging materials
for storage, and adding to water for washing food in the
preliminary and final stages of distribution. As of June
2001, ozone has gained FDA approval as a sanitizer not
only for food contact surfaces but also for direct application
on food. Currently, 90% of Fortune 500 companies in
the food industry are already using ozone in some of their
applications.
Safety Limits of Ozone
The concern of overdose of ozone is more related to
exposure in the air and less in the water, depending
on applications. Various reputable agencies worldwide
have published recommended safety levels in the air
which can be referred.
Ozone Mythology
Myth #1 All air cleaners sold for residential use produce
hazardous ozone and are therefore inherently dangerous.
All reputable bodies including the US EPA, FDA, OSHA,
ASHRAE and ACGIH have acknowledged standards
for ozone accumulation and exposure levels. As long as
manufacturers adhere to the suggested conservative
standards of exposure, the probability of developing health
risks should be very low. Myth #2 Low-level altitude pollution or smog is due to ozone.
It is true that wherever smog levels are high, so are
the measured ozone levels. And while ozone is easy to
measure, hydrocarbons are not. In addition, ozone is always
present in levels consistent with the hydrocarbon (pollution)
level, therefore the common assumption is perpetuated that
ozone is the culprit. But it’s just not so. Ozone forms naturally
when sunlight reacts with man-made hydrocarbons in the air
(generated by automobile exhaust and smokestack emissions,
for example). Hence, the more hydrocarbons there are, the
more ozone is produced. Moreover, it is the ozone produced
naturally outdoors that is actually nature’s secret for
helping to break down those harmful hydrocarbons and other
pollutants. Myth #3 Ozone is the toxic agent in polluted air
Many people believe that the offensive odors, burning
eyes and aggravated respiratory problems associated
with air pollution, are all due to high levels of ozone in
common polluted air. The fact is that they mistake
hydrocarbons, oxides of carbon, sulfur and nitrogen,
halogenated by-products, lead and other sulfur compounds –
all these irritants and more – for a single scapegoat: ozone.
These other pollutants do indeed cause eye, nose and throat
irritations. In their absence, the irritating effect of ozone at
the low concentration levels is a far cry from what is
commonly assumed. Myth #4 Ozone destroys the sense of smell
Ozone is an effective deodorizer because, as an effective
oxidizing agent, it eliminates odour, especially the organic
based odour such as are commonly found in the kitchen when
cooking. The effect is not in the nose or the brain where
the true sense of smell is experienced. The effect is rather
to chemically change the noxious chemicals by oxidizing
molecules of carbon, hydrogen, sulfur and nitrogen, to odour-free
molecules like carbon dioxide and water. Ozone does not
mask the odour, it changes or neutralizes it. That’s the ideal
answer.
Ten Advantages of Ozone Technology
-
One of the biggest advantages of ozone may be its
relatively low cost in comparison to other technologies.
-
Ozone will neutralize virtually all organic odour,
specifically those that contain carbon as their base element.
-
Ozone is also less corrosive to equipment than most
chemicals currently being used, such as chlorine.
-
Ozone generators clean the air and may reduce
the risk of microbiological infections.
-
Applications of ozone are generally quick and easy as
units are portable and only require a minimal amount
of time to treat the average room.
-
Ozone has been found to be an excellent disinfectant,
especially for the treatment of water and waste water.
-
Ozone has been found to be an effective broad-spectrum
antimicrobial but because it can be used in gaseous form,
it can give a complete coverage of all surfaces.
-
Ozone technology can be applied with very little if any
manpower.
-
An important advantage of ozone use in food processing
is that the product can still be called organic.
-
Ozone kills bacteria within a few seconds by a
process known as cell lysing. Because of this,
microorganisms cannot develop ozone resistant strains,
thus eliminating the need to change biocides periodically.
Reference: Some information has been extracted from
the book ‘Fresh Air For Life’ co-authored by Dr Allan
Somersall and Dr James Marsden. |
