[Posted in 3 parts, combined here into one. BIG]
Hi,
Confusion over this issue is manifest. Every time it comes up people
provide links to sites "explaining" ozone. Invariably the sites are set up
by the manufactures of ozone generators. The reference to a site in the
last digest was one of these. Do you believe the cigarette vendors claim
that smoking is SAFE. If you make a product are you going to say "DONT
USE IT IS NOT SAFE".
These sites have a bias. The problem is that ozone does work. It
removes odors. Used in controlled situations it is safe. Used in a
home environment it creates the possibility for health effects that the
manufacturers due not mention. Attached is the full article I wrote for
a bird list. At the bottom are citations provided by a toxicologist
from Canada. The article is about parrots. Birds have very sensitive
respiratory systems. The possible danger from ozone exposure is much
greater for them. However, this danger is still possible for humans and
ferrets. I apologize for the length but I do not want to post it piece
meal.
Ozone generators are air cleaners, not air filters. An air filter draws
air through a filter of some kind. The filter material allows the air to
past through but catches the air borne pollutants in the filter material.
Ozone air cleaners remove nothing from the environment. Bacteria are
neutralized and all airborne pollutants are electrically charged so that
they are attracted to the floors and walls of the room. The pollutants
will continue to build up on the floors and walls till they are removed by
some other means.
To understand Ozone generators you must firsts understand what Ozone is and
what its effects are. Ozone is a very special kind of oxygen molecule. A
molecule is a group of atoms that are electrically connected to each other.
Normally oxygen exists as O(2). The two in parentheses represent a sub
script(most email programs can't deal with them). This symbol stands for 2
atoms of oxygen bound (electrically connected) together to form a molecule.
This combination of oxygen atoms is stable. In other words O(2) tends
to stay O(2) and not change into some thing else. When we say we are
breathing oxygen we are breathing O(2). The air we breathe contains O(2)
along with many other gases. Ozone is composed of three atoms of oxygen
(written as O(3)) bound together. Ozone is not stable. It is very
reactive with other elements (O(3) very much wants to become O(2)). Ozone
is described (Encyclopedia Britannica) as an irritating, pale blue gas
that is explosive and toxic, even at low concentrations. It is used as a
bleaching agent for organic compounds; as a strong germicide to serialize
drinking water as well as to remove objectionable odors and flavors.
As stated above ozone is toxic. In controlled exposure studies
(Encyclopedia Britannica ) it reduced the ventilory capability of healthy
people in concentrations as low as 0.12 parts per million. Ozone is also
toxic to plants at levels of 0.01 to 0.05 parts per million with an
exposure time of several hours. Ozone can also cause breathing disorders
such as bronchitis. Parts per million is a way of measuring the
concentration of a gas. An ozone concentration of 0.01 parts per million
means that for every 100 million particles there will be 1 ozone molecule.
This is not very much ozone and it is still harmful to plants.
Ozone does exist in the atmosphere. Everyone has heard discussions of the
problems with the ozone layer. The ozone layer in the atmosphere exists at
a very large distance from the earth. We do not breathe this ozone. The
atmospheric ozone shields us from some of the Sun's radiation. Ozone is
also generated when an electrical spark passes an atmosphere containing
oxygen. This happens when lightening strikes the earth or an electric
motor runs (Yes your laser printer generates some ozone). The key thing to
remember is the concentrations that you breathe from lightning and electric
motors are very low and of a short duration..
Ozone generators use an electrical mechanism to generate Ozone gas. Ozone
generators will clean the air. Bacteria in the air are neutralized. Ozone
reacts with most airborne particles and the particles are attracted to
floor and walls. The particles are not in the air for you to breathe but
they do build up on your floors and walls. People that claim that Ozone
generators will reduce air borne pollutants are correct. The problem of
removing the residue that builds up on the floors and walls is ignored.
The problem is the Ozone cleaners are dangerous. Ozone is dangerous
to humans and plants even at very low concentrations. The study in
Encyclopedia Britannica found that levels as low as 0.12 parts per million
have a negative effect on human respiratory systems. None of the ozone
cleaner manufactures I found quoted the ozone they generate in part per
million so there is no way to compare their output to "safe" levels.
Recent media articles have indicated that at least some Ozone generators
do generate dangerous ozone levels. You will read testimonials from Ozone
cleaner users who say that the units have changed their lives, asthma
suffers can breathe again etc. These are true. Initially the Ozone
cleaners would remove all of the air born pollutants making it easier for
asthma suffers to breathe. However, the continued exposure ozone could
effect them in a very negative way unless the ozone levels are controlled
very carefully. None of the ozone cleaners I have encountered have
controls calibrated in parts per million . How do you set a safe level?
Remember that very low levels of Ozone have been shown to be harmful.
There is no standard for the level of ozone that is safe for parrots. We
do know that avian respiratory system is much more sensitive than the human
system. The corollary is that the "safe" ozone level would be much lower
than the safe ozone level required for humans. How low is safe enough?
This is a question does not have an answer. The only safe thing to do is
not use Ozone air cleaners.. Standard HEPA air filters are a much better
choice. They do not neutralize bacteria. They only remove them from the
environment. You must change/clean the filters regularly. However, they
do not generate poisonous gases.
OZONE
CLINICAL EFFECTS
A. Damage has occurred at concentrations as low as 0.5 PPM for
2 hours of exposure.
B. Patchy damage of the ciliated cells of the upper airway may
be seen after exposure to 0.2 to 0.5 PPM for 7 days, to 24
hours per day, in various experimental animal species.
7.3 MINIMUM LETHAL EXPOSURE
A. The lowest published lethal concentration via inhalation
in humans is 50 ppm for 30 minutes (RTECS, 1996).
B. Damage has occurred at concentrations as low as 0.5 ppm
for 2 hours of exposure (Stephens et al, 1974).
C. Type 1 pneumocytes may be killed at 0.8 ppm for 12 hours of
exposure.
D. Clara cell damage occurs at 0.5 to 0.8 ppm for 90 to 180 days
of 8 hours per day exposure (Boorman et al, 1980).
E. Patchy damage of the ciliated cells of the upper airway may be
seen after exposures to 0.2 to 0.5 ppm for 7 days, 8 to 24 hours
per day, in various experimental animal species (Menzel, 1984).
7.4 MAXIMUM TOLERATED EXPOSURE
A. The actual concentration at which ozone exerts toxic effects in
any individual depends on many factors, including morphology of the
airway passage, age, sex, dietary and hormonal status, pre-existing
disease states such as asthma, and capacity of cellular protective
systems based on superoxide dismutase, glutathion peroxidase, and
catalase (Mehlman & Borek, 1987; Clayton & Clayton, 1994).
B. The extent of lung damage is generally a function of
concentration of ozone rather than duration of exposure
(Stephens et al, 1974b).
C. Heavy exercise increases sensitivity to ozone for forced
respiratory function (Goldstein et al, 1985).
D. In one study, repeated exposure to 0.2 ppm ozone did not produce
cumulative effects on respiratory function, exposure to 0.35 ppm
produced greater decrements in FEV on day 3, but not days 4 and 5
of exposure, and effects were greater with 0.5 ppm, but were not
present by the fourth day of exposure. The authors concluded
that the respiratory effects of short-term exposure to ozone are
respiratory effects of short-term exposure to ozone are cumulative,
but that a period of adaptation follows after improvement in
pulmonary function, but also fewer subjective complaints
(Folinsbee et al, 1980).
E. Effects of Ozone in Humans - Occupational Exposures (Beard, 1982):
Ozone Subjective
Concentration Complaints
(ppm)
_____________ ______________________________
0.25 None
0.3 to 0.8 Throat irritation
0.9 peak Throat irritation,
lassitude, headache
irritation of nose and eyes,
chest tightness
0.47 Mucosal irritation
0.94 Severe mucosal irritation,
sleepiness
Greater
than
0.94 Pulse increase, sleepiness,
headache
0.1 to 0.6 Substernal pain, cough,
mucous membrane irritation
Bruce and critter
[Posted in FML issue 3386]
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