Ions Good for You?
Static explores the reputed physiological effects of ions.
a hundred years ago, it appeared as if all the important
discoveries in physics happened almost simultaneously.
For example, Wilhelm Röntgen discovered and developed
x-rays, and Henri Becquerel and the Curies discovered
radioactivity. It was soon realized that both phenomena
had effects that could be put to very important use
in industry, medicine, and other scientific fields.
the discoverers themselves were not aware that exposure
to these phenomena could pose a health hazard. Röntgen
is known to have looked directly into an x-ray beam
to determine whether it had any effect on the eye, Becquerel
always wore a lump of pitchblende in his waistcoat pocket,
and Marie Curie developed radiation damage to her hands
from handling radium.
x-rays and radioactivity have many similarities, they
are obviously very different in nature. X-rays, being
associated with accelerated electrons impinging on certain
metals in vacuum, are not natural phenomena, whereas
radioactive processes have taken place since the first
is also interesting that the common by-products (i.e.,
atmospheric ions or air ions) of both processes when
taking place in atmospheric air were not recognized
until about the same time as the discoveries of x-rays
and radioactivity. It could be speculated that the cause
must be known before the effect can be discovered, but
this is not so. The existence of atmospheric ions could
very well have been predicted a century earlier. In
1796, Coulomb had already observed that an insulated
charged body would gradually lose its charge when exposed
to atmospheric air. However, it was not until 1899 that
Elster and Geitel and, almost simultaneously and independently,
C.T.R. Wilson demonstrated the existence of mobile charge
carriers in air and rightfully ascribed it as the result
of radioactive decay of mostly airborne nuclides such
as radon and its short-lived daughters.
nature of air ions has been discussed at length several
times in this magazine, so let it suffice to state a
few simple facts.1, 2, 3 Air ions are not
charged molecules or atoms. They are clusters of mostly
water molecules (say 1214) around an oxygen or
nitrogen molecule that has lost an electron (i.e., a
positive ion), or 810 water molecules around an
oxygen molecule that has gained an extra electron (i.e.,
a negative ion).
air ions are created equal. There is no difference between
the ions produced by radioactive decay of airborne materials
or by cosmic rays, and the ions produced in a technical
ionization system by accelerating incidental electrons
to sufficiently high energies. This technical method
of ionization is again, in principle, identical to what
happens when the field from a thundercloud induces corona
discharges from the tips of leaves or from lightning
should be stressed that ions are always created in pairsa
positive and a negative ion. In unipolar field ionizers,
one polarity is automatically held back, so it appears
as if only positive or negative ions are produced, but
that is not so.
do not live forever. They recombine with oppositely
charged ions, they combine with aerosol particles, and
they plate out on surfaces. Therefore, the reason for
a more or less constant ion concentration of some hundred
ions of each polarity per cubic centimeter (at sea level)
is the constant production of maybe 510 ion pairs
per cubic centimeter per second caused by natural radiation.
So to keep a high ion concentration in a given volume,
ions have to be constantly produced.
ions have a very important role to play in industry,
namely that of neutralizing charges on insulators. In
fact, the use of a bipolar mix of air ions is the only
way by which the field from a charged insulator can
be neutralized. The charge can never be removed, but
the field from the charge can be neutralized, and that
is just as good. As that problem has already been treated
in detail, this article concentrates on the claims of
direct or indirect effects of air ions on human beings.
from the very first detection of air ions, there has
been speculation about possible hygienic, physiological,
or other types of effects. The first paper may have
appeared as early as 1923. Very few, if any, of these
first papers deserve the designation of scientific
papers, which should only deal with properly described
and properly conducted investigations. Almost all reported
investigations were purely anecdotal. In my opinion,
one of the reasons for this was that usually the investigations
were carried out by physicians and other laypeople without
the guidance of physicists with a proper knowledge of
example, in the 1930s, it was rather common in Germany
to treat a variety of ailments, such as asthma, bronchitis,
and other airways-related problems, by letting the patients
(apparently) inhale negative ions. Some of the administrants
of these treatments, usually medical practitioners,
reported rather astonishing results. At a certain point
in these experiments, somebody had the good sense to
ask a real expert to examine the ionizers to find out
what they were actually doing. The all-time-ever expert
on atmospheric electricity, Hans Israël, agreed
to do this.4 Years later, I heard Hans Israël
summarize his investigation. It appeared that the ionizers
used by some of the doctors with the most beneficial
results did not even contain a high-voltage supply;
that is, they did not produce ions at all.
previous story is a good example of a negative-ion myth.
Repeatedly, it has been reported that negative ions
are good and that positive ions are bad, usually with
little if any scientifically rigorous documentation.
of the oldest claims concerning the effect of ions is
that air rich in negative ions is fresh and that air
rich in positive ions is stuffy. Of course, it is difficult
to prove or disprove such statements, as freshness and
stuffiness are subjective quantities for which there
is no physical method of measurement. Therefore, let
us be subjective. Let us assume that most people will
agree that the air at a mountaintop deserves to be called
fresh. Now, it just so happens that this air is rich
in positive ions, the concentration being maybe 34
times greater than at sea level. The freshness and the
positive ions have nothing to do with each other. The
freshness could be caused by the air being unpolluted
and cool, and the high positive-ion concentration is
simply a result of the electrode effect.
us also assume that most people will find that during
a thunderstorm (before the rain sets in) the air may
be considered less than fresh, maybe even stuffy. This
same air is rich in negative ions. The stuffiness might
be explained by high humidity and other thermophysical
factors, and the high negative-ion concentration is
simply an effect of the strong negative field from the
base of the thundercloud to the ground.
example of the negative-ion myth concerns the effects
of ions on the cilia in the respiratory tract. From
1957 through 1963, a series of papers were published
by Krueger et al., who suggested that air with an excess
of positive ions caused a deceleration of cilia activity
and of the rate of mucus flow, whereas air with an excess
of negative ions produced changes in the opposite direction
and reversed the effects of positive ions.5,6
In other words, exposure to negative ions would increase
the rate with which the airways were cleared.
other researchers failed to show any effects of unipolar
ionized air on cilia frequency and mucus flow, the papers
of Krueger et al. were widely quoted; even today, there
are still positive references to their work. This is
in spite of the fact that, in 1971, Andersen's book
Mucociliary Function in Trachea Exposed to Ionized and
Non-Ionized Air demonstrated without any doubt that
the claimed effects do not exist.7 Andersen
gave a very thorough and sober evaluation of all the
previous work and pointed out a series of experimental
shortcomings that made any conclusion drawn from the
results dubious. Andersen also conducted a large experimental
study under carefully controlled conditions (thermodynamic,
aerodynamic, and electrical) and using modern equipment.
He demonstrated that there was no relationship between
ion concentration (of either polarity) and cilia frequency.
His conclusion was as follows:
is concluded thatthe application of unipolar or bipolar
ionized air in the therapy of diseases in the airways,
and active control of ion concentrations in homes and
places of work etc. for prophylactic reasons must be
considered without any experimental-physiological basis.
ion-balance myth is a special version of the negative-ion
myth. The concept of ion balance is not really defined
in atmospheric electricity, but it is probably supposed
to mean the ratio between the concentrations of negative
and positive ions. In a closed room, it is obviously
possible to control this ratio by producing an excess
of ions of one polarity. However, this is not what is
normally meant when references are made to changes in
ion balance. It is often claimed that certain procedures
or even just certain materials will selectively remove
one polarity of ions. Over the years, it has been claimed
time and time again that if the ions removed were the
negative ions, the result would be a bad ion balance.
this context, we are talking about naturally occurring
ions, that is, ions produced primarily by the decay
of airborne radioactive materials. As already mentioned,
ions are always produced in pairs; therefore, the production
rates for positive and negative atmospheric ions are
identical. In the free lower atmosphere, a state of
equilibrium will be reached at which the constant production
of ions is balanced by positive and negative ions recombining
with each other, combining with aerosol particles, or
diffusing to ground. The result will be a state with
a positive-ion concentration maybe 2025% higher
than the negative one. The difference is caused by the
positive ions having a somewhat lower mobility than
do negative ions (1.4104 m2V1s1
and 1.8104 m2V1s1,
respectively). Positive ions therefore also have a lower
diffusivity, and this is balanced by a higher concentration
of positive ions so that the actual removal rate by
diffusion is the same for both positive and negative
actual values of the ion concentrations depend strongly
on the concentration of aerosols or pollutants. In relatively
clean air, the concentrations of the ions may be in
the hundreds (per cubic centimeter), in highly polluted
air, they may be 10 times as low. But the important
fact is that the ratio, the ion balance, is almost the
same, about 1.21.3.
high level of pollution will turn most of the ions into
charged particles, or heavy ions, but with no preference
for either polarity. Since the 1930s, it has been known
that the attachment coefficients for negative and positive
ions attaching with aerosol particles are almost the
same, resulting in a population of aerosol particles
divided more or less equally between negative, positive,
and neutral particles. This is true with moderate pollution
levels. With very high aerosol concentrations, there
are not enough ions to charge the aerosol particles,
and the neutral particles will dominate.
Winds Are Rich in Positive Ions. It seems reasonably
well documented that the hot winds like the Föhn,
the Santa Ana, the sirocco, and so forth have a detrimental
influence on people's well-being. To explain the special
properties of these phenomena, it has often been postulated
that the winds, maybe especially the Föhn Alp wind,
are rich in positive ions and therefore, according to
the negative-ion myth, will feel stuffy and unpleasant.
I have never been able to find any hint of a trustworthy
theory explaining how a unipolar ionization of the air
mass could take place, let alone explain how the charge
could be carried hundreds of miles over the mountains
without dissipating. I have also not seen any proper
scientific papers demonstrating the excess of positive
ions in these winds.
Materials May Ruin the Ion Balance. Around 1960,
a peculiar campaign started in several European countries.
The campaign was based on the negative-ion myth. It
was claimed that floor coverings of vinyl tiles would
ruin the ion balance, meaning that they would create
an excess of positive ions, whereas linoleum floors
would allegedly leave the ion ratio untouched. No scientific
proof for the claim and certainly no measurements were
offered, but not a week went by without statements from
newspapers, magazines, radio, or television about the
harmful effects of vinyl tiles.
major Danish company that was economically hurt by the
campaign asked if the problem could be investigated.
I conducted a series of ion-concentration measurements
in rooms that were as identical as possible, except
that half of the rooms tested had linoleum floors and
the other half had vinyl tiles. No significant difference
between the two types of rooms could be detected with
respect to either the absolute values of the ion concentrations
or the ion ratio.
Building Syndrome and the Ion Balance. Over the
past 40 years, the interest in the indoor climate has
been steadily growing, and in the 1970s, the concept
of sick buildings emerged. It appeared that many people
felt uncomfortable and maybe even sick when working
in certain buildings, especially modern buildings. The
symptoms were usually vague, such as headaches, eczema,
dry skin, problems with breathing, and so forth.
suggestions for the causes were proposed, including
mold fungi and dust mites, but both of these causes
are connected with inefficient ventilation. It was also
suggested that the cause could be a bad ion balance.
Many well-controlled experiments were performed in many
different types of buildings. None of the experiments
showed any significant deviations from the normal ion-concentration
values. Note that there probably is such a thing as
a sick building, but it apparently has nothing to do
with atmospheric ions.
Ions and Pollution. A peculiar variation of the
ion-balance myth has emerged over the past decade. It
states that positive ions and air pollution are intimately
related; that is, positive ions will preferentially
attach to airborne particulates. First of all, this
is not true. As already mentioned, the attachment coefficients
are very similar for both positive and negative ions.
Second, this myth is taken as another proof that positive
ions are harmful because they attach themselves to pollutants.
If this really were the case, it would mean that polluted
air would have an excess of negative ions, as the pollutants
would swallow positive ions. However, as already stated,
this is not so. Polluted air may have low concentrations
of both positive and negative ions.
examples treated above illustrate rather well a statement
made as early as 1985 by Reinhold Reiter, a recognized
expert on atmospheric electricity: "Nearly all relevant
assertations about harmful or beneficial effects of
small ions fail to realize the fundamental elements
of atmospheric electricity."8
Ions Good for You?
far, the question posed in the title of this article
has not really been answered. Instead, discussion has
focused on some physical facts and has tried to quench
some unfounded myths. Before trying to answer the question,
it is important to look at what ions can actually do.
Atmospheric ions consist of a nitrogen or oxygen molecule,
a few water molecules, and an elementary charge. Human
beings are constantly exposed to a mixture of nitrogen,
oxygen, and water vapor, so what difference would it
make if there were also a positive or negative charge
in industry, and especially those in the world of electronics,
know what it means when a flow of ionized air is directed
toward a charged insulator. If the flow is properly
balanced, the charge on the insulator can be neutralized
because the ions are able to give off their charge.
It is the only way that a charged insulator can ever
what does this have to do with human beings? If a balanced
flow of ionized air is directed toward an area of exposed
skin, the positive and negative ions will be neutralized
when plating out very close to each other, and the result
may be some very weak currents on the outer layer of
the skin. However, it is a completely different story
if a unipolar (say negatively ionized) airflow is used
instead. If the person is not grounded, the body will
acquire a gradually increasing negative voltage until
a discharge, usually a spark, takes place or until the
unavoidable leakage current balances the ion current.
case becomes much more interesting if the person is
grounded. Let us suppose that the person is placed on
an insulative sheet and that a grounded wrist strap
is attached to the right wrist. Now, if a unipolar (say
negatively ionized) airflow is directed toward the person's
exposed back, the ions will plate out on the skin and
be neutralized, and their charge will run through the
body to the wrist strap. If this process has an effect,
it would not be because of the ions per se. The ions
have only served as carriers of the charge to the body.
So the questions are "can these currents have any effects?"
and "what kind of paths do the currents follow?" I am
far from sure that I can answer these questions, but
I can tell a story.
few years ago, I was contacted by a Danish architect;
let us call him Mr. W. He was very interested in indoor
climate and wanted to learn more about ions and their
effects on people. Of course, I told him that ions had
no (direct) effect on people, but sure, I could teach
him something about ionizers for air-cleaning purposes
and for neutralizing charges on insulators.
W believed in the healing effects of (negative) ions.
He used unipolar ionizers for treating patients suffering
from various ailments and reported surprisingly positive
results. I insisted that it was not the ions but their
charge that was responsible for any effects. After some
pilot laboratory experiments, it was demonstrated that
positive and negative ions were equally effective. The
flow of unipolar ionized air seemed to be especially
effective in healing sores and wounds and in reducing
(and not only temporarily) pains and side effects in,
for example, cancer patients undergoing chemotherapy
or radiation treatment. Mr. W also had some ideas that
the method actually was a kind of acupuncture, but in
any event, it was definitely an alternative method of
the Western world, or at least in Denmark, the established
medical society frowns on anything alternative, especially
if it contains elements of sciences of which the established
medical society has no knowledge and experiencesuch
as physics. So there was no way that Mr. W could have
a clinical test of his method performed in Denmark under
proper medical supervision. However, in other parts
of the world, the attitude to alternative treatment
methods is quite different.
the prestigious Chulalongkorn University Hospital in
Bangkok, where acupuncture is a recognized specialty,
the chief oncologist, Kris Chatamra, had heard about
Mr. W's results and offered to set up a small pilot
project as a forerunner for a proper clinical test.
The pilot project was conducted in June 2002. Chatamra
had chosen four very sick patients for the test: three
cancer cases (considered terminally ill) and one patient
with a chronic infection (diabetes related) on one foot.
All four patients were in severe pain and required regular
and strong analgesia.
patient to be treated was placed on an insulative sheet
on a cot, and a wrist or ankle strap was attached to
the patient. A flow of unipolar ionized air was directed
toward a selected exposed part of the patient's skin.
The strap connected the patient to the ionizing unit
through a feedback system, which monitored the ion flow
and the total dose. The current to the patient was in
the order of µA, and the exposure time was typically
90 minutes. The length of the trial was 10 days. The
patients were fully assessed prior to the trial and
also assessed daily during the trial by a specialist
nurse. Pain assessment was conducted by patient scoring
and by the amount of analgesia required daily.
the end of the pilot project, Chatamra concluded:
results are encouraging: All patients required less
analgesia (one patient actually stopped taking it altogether).
The chronic wound also showed accelerated healing, and
the patient is now discharged from the surgical unit.
None of the patients suffered any complications.
was a very small project. It did not prove anything,
scientifically speaking. But as Chatamra says, the results
are encouraging. A proper clinical test with all the
necessary precautions, such as double-blind testing
and the use of a control group, is planned.
role in the pilot project, and maybe in the (hopefully
upcoming) clinical test, has merely been that of a physics
consultant and observeran observer who has gradually
lost his belief that ions have no effect on human beings.
However, to quote Luke 15:7, "There will be more rejoicing
in heaven over one sinner who repents." Still, the negative-ion
myth and the ion-balance myth are nothing but that,
Niels Jonassen, "Ions" in Mr. Static, Compliance
Engineering 16, no. 3 (1999): 2428.
Niels Jonassen, "Neutralization of Static Charges
by Air Ions: Part I, Theory" in Mr. Static, Compliance
Engineering 19, no. 2 (2002): 2831.
Niels Jonassen, "Neutralization of Static Charges
by Air Ions: Part II, Experimental Results" in Mr. Static,
Compliance Engineering 19, no. 4 (2002): 2227.
H Israël, Atmosphärische Elektrizität
(Leipzig, Germany: Springer Akademische Verlagsgesellschaft,
AP Krueger and RF Smith, Proceedings of the
Society of Experimental Biology 96 (1957): 807809.
AP Krueger, PC Andriese, and S Kotaka, International
Journal of Biometeorology 7 (1963): 316.
I Andersen, Mucociliary Function in Trachea
Exposed to Ionized and Non-Ionized Air (Aarhus,
Denmark: Akademisk Boghandel, 1971).
RJ Reiter, Journal of Geophysical Research
90 (1985): 59365944.
Jonassen, MSc, DSc, worked for 40 years at the Technical
University of Denmark, where he conducted classes in electromagnetism,
static and atmospheric electricity, airborne radioactivity,
and indoor climate. After retiring, he divided his time among the
laboratory, his home, and Thailand, writing on static
electricity topics and pursuing cooking classes. He passed away in 2006.