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General theories

Q.01 - Can negative ion generation be affected by temperature and humidity?
Yes, it is affected. Negative ions are less likely to be generated as humidity rises because water, which ionizes the air, decreases. The ideal relative humidity for negative ion generation is said to be 40-60%. Theoritically, negative ions decrease as temperature rises, but practically this is not always the case.
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Q.02 - What are small and large ions?
Air ions are categorized into the following groups. Effects on the human body and the environment vary depending on the size.

(1) Ionized atom
An atom, which has lost an electron, is a positively ionized atom. An electronically neutral atom, which has obtained an electron, is a negatively ionized atom. They are said to exist only in the upper layers of the atmosphere.

(2) Small ion (aka. Lightweight ion, High speed ion)
An electron or an ionized atom attracts gaseous molecules while positioning itself in the center and combines with them to form a small ion. It is said that a group of small ions consists of 10 to 30 ion molecules.The mobility of a positive/negative small ion is around 0.136/0.210 (cm2/Vs), that is relatively high speed. Small ions are said to have more positive effects on the human body than any other ion.

(3) Large ion (aka. Heavy ion, Low speed ion)
A large ion is formed when an electron or a small ion is absorbed by mist or dust. Large ions have the same structure as small ions but weigh about 1,000 times more.Mobilities range from 0.00005 to 0.001 (cm2/Vs), that is relatively low speed. Large ions are more likely to be found in polluted air. They have less positive effects on the human body but they are said to be good for air purification.

(4) Middle ion
Middle ions can be found only when humidity is lower than a certain level. They have mobilities ranging about 0.001 to 0.01 (cm2/Vs), which is between those of small and large ions. They do not exist near the earth's surface.
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Q.03 - How can a negative ion count be measured?
Please refer to "Measurement Principles".
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Q.04 - What are the differences between static electricity and negative ions?
Static electricity is electricity at rest as the name suggests. It accumulates on insulators* such as plastics and remains there until it is discharged. Ions floating in the air can freely move.

You are more likely to get an electric shock when the air is dry because your body is more likely to be charged when humidity is low. This phenomenon is less likely to occur under high humidity because electricity flows away through water droplets in the air.

*Materials which do not allow electric current to flow
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Q.05 - Why do small ions have more positive effects on the human body than large ions?
Small ions are more likely to be absorbed by the lung due to the greater mobilities and larger diffusion coefficients than those of large ions, which is why it said small ions produce more effects on the human body.
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Q.06 - I heard air ions have life expectancies. How long can they exist in the air?
According to literature, small ions have life expectancies of 100 seconds +/-.
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Q.07 - How do small ions exist in our daily life environment?
For example, an oxygen molecule is ionized and combines with a water droplet to exist in the air. This is due to the polarization of the water molecule.
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Q.08 - Does an air ion continue to exist forever once it is generated?
No, it does not. Small ions are said to have life expectancies of about 20-30 seconds. This varies depending on the mobility and diffusion coefficient.
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Q.09 - What is a diffusion coefficient?
Air ions spread depending on the strength of the electromagnetic field. A diffusion coefficient shows how far they spread. Generally, negative/small ions have larger diffusion coefficients than positive/large ions.
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Q.10 - Why do negative ions decrease as humidity rises?
Ions are absorbed by a cluster of water droplets to exist in the air. The more there are tiny water droplets, the more negative ions are generated. Negative ions decrease when humidity is high because water droplets combine with each other and decrease.
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Q.11 - Can the reading of a negative ion counter be affected by ion winds?
Yes, it can be. An air ion counter has an internal fan and it sucks the air to measure the ion count. The reading can be affected if the suction flow rate is affected by winds because it determines the sizes of ions the counter detects. Some air ions are small and lightweight and some are large and heavy. Please refer to "Measurement Principles" for the details.
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Q.12 - Do negative ions generated by generators weigh more than other molecules in the air?
Most of negative ions generated by the corona discharging method have an oxygen molecule in the center. Negative ions do not weigh more than other molecules in the air because the mass of an electron is negligible compared to that of an oxygen molecule.

However, negative ions weigh more because they are combined with tiny water droplets to exist in the air.
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Q.13 - What is the definition of a negative ion?
According to literature, a negative ion in the air is a negatively charged tiny particle. An air ion is formed when a molecule absorbs an electron which is released into the air and then it combines with a tiny water droplet to exist stably and is floating in the air.

Air ions can be absorbed by dust or other tiny particles to form large ions. Thus, some molecules , which combine with each other, are electronically charged.
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Q.14 - Can negative ion density be affected by human presence?
Both negative and positive ion densities decrease by human presence. This is because humans absorb ions.
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Q.15 - An oxidation reduction potential meter, which claims to measure negative ions contained in the human body, was featured on TV. What is oxidation reduction potential?
An oxidation reduction potential meter does not directly measure negative ions contained in the human body. ORP (Oxidation Reduction Potential) shows an electronic energy to oxidize or deoxidize substances. Generally, ORP in alkaline solutions tend to have negative values (mV), which varies depending on the conditions. (It is just for your reference.)
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Q.16 - Why are harmful chemical substances and dust charged positively?
According to literature, harmful chemical substances chemically react with free radicals to form positively charged oxonium ions. Dust floating in the air is generally charged positively but some can be charged negatively by negative ions.
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Q.17 - Is an air ion made from an atom or an molecule?
An atom, a molecule and a cluster of molecules charged negatively or positively are air ions. Please refer to "Classification of ions".
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Q.18 - Is there a way to get a lot of negative ions other than by using a negative ion generator or by standing near a waterfall/fountain?
Radiation rays ionize the air. Some radioactive substances generate a large amount of negative ions. You have to be careful that the harmful rays they emit are within safety levels.
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Q.19 - Negative ion density is indicated in (pcs/cm3), (ions/cc) or (pcs/cc). Is there any difference?
There is no difference. They all show the number of negative ions contained per unit volume, which is the negative ion density.
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Q.20 - What is mobility of negative ions?
Mobility is the velocity of an ion which travels by Coulomb force where the strength of the electromagnetic field is 1 (V/cm). Please refer to "Mobility" for the details.
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Q.21 - I found a report regarding the Lenard effect which says "Negative ions have been proven to produce positive effects on animals". Is this true?
Lenard, Philipp Eduard Anton was a German experimental physicist. Such a report cannot be found. We have not read through all the papers on his research though. He would be famous for it if he had proven positive effects on animals.
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Q.22 - Some air purifiers generate negative ions. Which components of the air are negatively ionized?
It has not been fully elucidated how and which components of the air are ionized to form small ions. This is because ions react with molecules in complicated ways in the air as soon as they are created.

Oxygen molecules are ionized first due to its ionization tendency. Other molecules can be ionized depending on the density ratio.

A research report says that nitrate ions (NO3- + (H2O)n) are formed after the complicated processes. (Ogawa and others 1986)
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Q.23 - Do negative ions generated by generators pass through plastics?
They do not pass through plastics. For your reference, a certain amount of negative ions pass through clothing if it is made of breathable fabric.
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Q.24 - Air suction type ion counters suck air at different speeds (cc/s). Doesn't it affect the actual readings?
Theoritically, ion counters are designed to provide the same ion count regardless of the air suction rate. For example, the voltage applied to the detector or the shape is decided depending on the suction rate. Please also refer to "Measurement Principles".
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Q.25 - I heard gamma rays generate the same amount of negative and positive ions. Does this mean there is no point because the ions are cancelled out?
Negative ions are not all cancelled out even if the same amount of negative and positive ions are generated. If you have an ion counter, you can observe that some are not neutralized and exist independently.

You can enjoy negative ion effects even if you absorb the same amount of negative and positive ions. This is because negative ion generators which employ the old corona method produce positive effects on the human body while generating positive ions.

However, it is ideal if positive ions are not generated because they neutralize negative ions to lower the negative ion count.
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Q.26 - Please suggest some negative ion related books.
Here are some of the books we referred to.

· Medical domain - theory and practice of air ion (co-authored by Syouichi Kimura and Masahiro Taniguchi)
· Encyclopedia of applications of air negative ion (co-authored by Tomoo Ryushi and Hisao Sasaki)
· Air ion and life (Negative ion research association)
· Air electricity (authored by Shinichiro Kitagawa)
· Negative ion - principle of positive effects on the human body (authored by Toshio Ogawa)
Q.27 - Do negative ions with longer life spans have more positive effects on the human body?
Ions with longer life spans have less positive effects on the human body than those with shorter life spans. Negative ions, which have long life spans, are large ions and they have large masses. Negative ions that have long life spans are large ions as they have large masses. They are less likely to spread, be neutralized by positive ions or absorbed by tiny particles because they move slowly due to their large masses.

This means they have longer life spans than smaller ions do. Large ions are said to have less positive effects on the human body.

Thus, the longer the life span is, the less it has positive effects.
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Q.28 - What are the differences between ion counters which have a built-in fan and those which don't?
Most air ion counters have an internal fan. It sucks the air to select and measures small ions only because they have more positive effects on the human body.Large ions floating in the air are also sucked but they pass through without being detected. Please refer to "Measurement Principles" for the details.

We guess most of ion counters with no fan detect both small and large ions. There are counters which are designed to measure large ions only.
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Q.29 - Are ions with longer life spans better when generated by negative ion generators?
If ions are not consumed while they are alive, longer life spans are not always better.

Ions are no longer ions when they are absorbed by dust to form particles which are larger than large ions. When ions purify the air, they combine with tiny particles. If they are as large as or smaller than large ions, they are still ions.

Thus, ions which have longer life spans are better.
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Q.30 - Please show me how ions are chemically composed.
Historically, rockets and balloons have been used to analyze structures of air ions due to the difficulty of mass spectrometry under high pressure near the earth's surface. According to the research, nitrate, sulfur and carbonate ions were observed near the earth's surface, in middle and high latitudes, respectively.
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Q.31 - How can I give negative ions to fish in the tank? Will natural ores work?
Generally, negative ions refer to ions in the air. Historically, most research has been focused on air ions. You cannot treat ions in water and those in the air in the same way.

Negative ions can disappear in the tubing connected to the pump before they reach the water. Natural ores will not work. Very few air ions can be created in water where there is little air. Some ores can change the ratios of impurities or components contained in water as metal ions dissolve. This may have some effects on fish but these effects are not caused by negative ions.
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Q.32 - Positive ions can increase as negative ions increase. Does this result in less negative ion effects as they cancel out each other?
Positive ions tend to increase as negative ions increase. They cancel out each other under some physical conditions. Thus, it is ideal if positive ions are not generated.

However, negative ions are not completely neutralized. Both ions can exist independently and be observed without being neutralized.

Effects on the human body produced by positive and negative ions, which exist independently, can be found in literature published in the past. (Effects by typical negative ion generators which employ the corona discharge method) This suggests negative ions work if the ion count exceeds that of the positive counterpart.

There is very little information on relations between the negative/positive ion ratio, which is so called the ion balance, and the effects on the human body. It will be elucidated by further research.

Negative ions have shorter life spans than positive ions because they are more likely to spread or be neutralized/absorbed by other substances due to their larger mobilities (velocities per 1 V/cm or 1 V/m).
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Q.33 - What is the difference between negative ions and ozone?
The differences are as follows.
Negative ions are negatively charged, while ozone is electronically neutral.

Effects on the human body
It is said that negative ions produce positive effects on the human body. Ozone is a gas which has a high ability to oxidize other substances. Highly concentrated ozone is harmful and it can even cause death. The safety standard is set by the Ministry of Health, Labour and Welfare, which is 0.1ppm or less in working areas.

The ozone layer located in the stratosphere contains highly concentrated ozone. Ozone works to prevent an excessive dose of UV radiation from reaching the earth's surface as it is harmful. The deodorant and sterilization effects of ozone are utilized in the medical, environmental and other industries. Negative ions purify the air and produce positive effects on the human body and are used for home appliances such as air purifiers/conditioners and hair dryers, and various industrial products as well.

Ozone generated with negative ions
Negative ion generators which employ the corona or other discharging methods generate ozone when electricity is discharged. You may have smelled ozone (simulating odor) when lightning occurs because ozone is generated in the atmosphere.
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Q.34 - You state that negative ions are found around a waterfall. Does rain or my shower produce negative ions?
Rain and your shower produce negative ions because they are generated by the Lenard effect where water splashes. Far more negative ions can be found in the basin of a waterfall because water is splashed more violently and humidity is lower. Negative ions can exist stably when humidity is 40-60%, while it is usually higher than this level when raining or in your shower room. Please also refer to "Why do many negative ions exist in a public bath or shower room?".
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Q.35 - What does the Japan Association of Ion Research and Application do?
This NPO conducts ion related research and provides information to the public. Their service includes ion measurement, issuing certificates to manufacturers of ion related products, organizing symposiums/lectures and publishing newspapers/bulletins.

This organization was established in order to maintain and improve health conditions of the citizens and to improve productivity and safety of the food, agricultural and other industries through research of functional ions and providing ion related information.

The JISB9929 Standard for measurement method of airbone ion density was deliberated and established by the JIS committee. An ion counter, which they developed, was used to establish this standard. In Japan, this is the only official standard for air ion measurement.

[Japan Association of Ion Research and Application] (Japanese only)
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Q.36 - How does tourmaline generate negative ions?
It is thought that the surface of tourmaline is electronically charged when pressure is applied to it or when temperature changes and then the electronic charge ionizes the air.

Tourmaline generates little amount of negative ions when no external force is applied to it because it is electronically neutral. Actually, it is electronically charged as friction is applied to it by the atmospheric pressure and the surrounding air but the electronic charge is cancelled out by ions floating in the air.

The piezoelectric effect is a phenomenon where tourmaline is electronically charged when pressure is applied to it. The pyroelectric effect is a phenomenon where tourmaline is electronically charged when temperature changes.
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Q.37 - What is tourmaline? What is it used for?
Tourmaline is a natural ore which has many color variations. This precious stone, known as a birthstone for October, is classically used for jewelry.The raw ore, which is not good for jewelry, is used for various health related products as it produces beneficial effects on health. A typical application is a negative ion product as tourmaline generates negative ions when pressure is applied to it.

For more information about tourmaline, you can refer to What is tourmaline?.
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Q.38 - Please give me some advice on how to use a negative ion generator effectively in a room.
We suggest you should:
1. make sure the blow off point of the negative ion generator points toward you.
2. install the generator so that it is located as far away as possible from the wall/floor. (Ions can be absorbed.)
3. ventilate the room on a regular basis.
4. wear clothing which is less likely cause static electricity.
5. stay barefoot in the room (You can absorb more ions due to the grounding effect.)
6. maintain the discharging electrode by regular cleaning.
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Q.39 - Is there an official standard for negative ions?
There is a JIS standard as shown below.
JISB9929 Standard for measurement method of airbone ion density
In Japan, this is the only official standard for measurement of air ions as of Jun 2010.

Here is the table of contents.

[Table of contents]
1   Scope
2   Normative reference
3   Terms and definitions
4   Types and classification of measuring methods of airborne ion
4.1   Measuring method and classification of airborne ion density
4.2   Measuring method and classification relating to the evaluation of amount generated by the ion generator
5   Measuring method of airborne ion
5.1   Measuring method of airborne ion density
5.2   Measuring method relating to evaluation of the generated amount by the ion generator
6   Preparation of report
Annex 1 (informative)   Airborne ion density measuring device
Annex 2 (informative)   Method for evaluation of the removal effect of electricity fan ionizer with the charged plate monitor
Annex 3 (informative)   Method for generation of airborne ion
Annex 4 (informative)   A relationship between life span of ions and aerosol concentration
Annex 5 (informative)   A laminar flow test method within a condenser at a time of designing
[Quoted from]
Japanese Standards Association
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Contents of: Negative Ion FAQ
Contents of: Theory (Negative ion & Tourmaline)
· Negative Ion Generators
· Ion Counter
· Tourmaline Sheet
· Tourmaline Stones Powder
· Necklace
· Bracelet
· Bath Products
· Supporter
· Negative Ion Clothing
· Tourmaline Bedding
· Girdle
· Pet Supplies
· Home remedies for stiff neck
· Negative Ion Accessories
· Cosmetics

· Tourmaline Products
What is a negative ion? (13)
What is tourmaline? (7)
Tourmaline explorer (11)
Negative Ion FAQ (140)
Ideal amount of negative ions (1)
Actual negative and positive ion measurements featured in literature and media (1)
Learn more about negative ions (25)
How to choose the best negative ion generator (5)
How to choose the right negative ion products (9)
Misunderstanding about negative ions (10)
Theory of Air Ion (14)
Negative ion effects reported in medical literature (13)
Lenard effect (2)
Negative ion counter comparison chart (2)
Corporate customers (15)
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