Full member Miho NAKAZATO
Do. Akiko KENMOCHI
Do. Tsuneo ISHIKAWA,
Do. Akiko SUGAHARA
Air ion air quality negative ion
Positive ion formaldehyde indoor air contamination
first
During recent years, there is a lot of attention being given to the air cleaning action of negative ions.
It has been pointed out that toxic chemical compounds, including formaldehyde are the main causes for indoor air contamination. So, if we could clear and reduce them by negative ions, it will be highly effective to create good indoor condition.
However, it has become obvious to some extent that negative ions will take solid suspended particulates in the air away, but when we talk about if it will also be effective to gaseous toxic chemical compounds, scholarly study has just begun.
So, in this study, first we will make the correlations of closed system air ions and formaldehyde clear with measurements, and consider the capability of how air ions will contribute to the improvement of our living environment.
Air ions overview
Air Ion is the situation of atoms or molecules in the air being positively or negatively charged.
There is a high association with air ions and atmospheric electric field, and it could be said that it is the source of electrical phenomenon in the atmosphere.
Air ions will be classified into small ions, medium ions and large ions according to the particle sizes and mobility. However, the characteristic features and compositions vary widely, as large ions and medium ions are the small ions that are attached to neutral-particle (fine particle aerosol) in the air and charged particle.
Small ions have overwhelmingly bigger influence to the human body and the environment compared to large ions and medium ions, it is because the mobility of ion is bigger and they are easier to get attached to atmospherically particulates and to biological bodies.
So, for that reason, in this study, we will be mainly subjected to study small ions.
It has come out that air ions are nearly connected to the air cleaning level.
It has been reported by numerous researchers that air ionic concentration and air ion ratio will vary considerably with location, and according to the pollution of air, air ionic concentration will decrease, and air ion ratio (n+/n-) will increase.
Therefore, we have to require air ionic concentration and air ion ratio both of the consideration for the recommended air ions environment.
As when it is n+/n-, it will have an onset of the positive ions action, and when n+/n-, it will have an onset of negative ions action, So it could be said that the conditions where negative ions are more than positive ions is the better air ions condition to biological bodies.
Moreover, the luck of air ions will affect bad influences to the biological body, so when mount of air ions are extremely low or no ions condition are no good.
We had the preliminary measurement with using Gerdien condenser air-ionometer trying to recognize the air ions environment around our imminent environment like pinewood forest, water spout, housing, crowded streets.
I will omit details here, but as anamnesis studies say, hmmm, air ions environment varied a lot to the places.
In a room inside, it depended on building’s engineering systems, humidity, air ventilation, or how many people are inside of the room, and outside, it depends on the factors like air cleanliness.
At the same time, air ionic concentration is changing every minute, and it was manifestly apparent that it is sensitive element that will get influenced only by imperceptible air currents.
The measurement of air ions and formaldehyde concentration with closed system equipments
We did the following experiment to clarify the correlation between negative ion concentration and formaldehyde aerial density, and the reduction effect of formaldehyde by negative ions in the air.
However, it is thought that the negative ion that is generated with electrical type vary from the negative ions that is generated with water spallation type, as they often do not have cluster of water, and that they have disadvantage for gaseous substance removal.
But these days, the system has become popular and adapted to many electrical products and there are many chances to be introduced into our living environment.
Therefore, in this experiment, we used electrical type of negative ions generator.
In particular, formaldehyde will be degraded by the strong oxidizing action like ozone, so from some of electrical systems, we chose no vibrating electron radiation formula negative ions generating system which generate less by-product.
In this experiment, we measured formaldehyde concentration in the measurement condition of Table 1. We put plywood of Fc2 as pollution source, negative ion generator, and formaldehyde basic indicator into desiccators as it its shown in the Figure 1.
In measurement 1, and 2, we measured formaldehyde reduction effect, and measurement 3, and 4, we tried to find how the desiccators of gating mechanism which will be influenced to fill in the former experiment measurement 1, and 2.
Instruments for the measurement
Glass desiccator’s internal diameter 260mm,
Depth 280mm, intermediate plate internal diameter 200mm, intermediate plate depth 80mm
pollutant source Fc2 plywood (formaldehyde emit level standard /average 5.0mg/L) 100*100*12mm piece
formaldehyde basic indicator formaldehyde meter400(JMS caseload fuel battery system)
Negative ion generator inti ITC-301A (Andes electric products, no vibrating electron adiation formula)
Fig. 1measurement device diagrammatic illustration
Measurement No. of the cap of electronic power desiccators of Negative ion generator
Measurement? ON,OFF
ON: in the 60 minute
OFF: in the 175minute
Switching on
First switching about four seconds (in the 60minutes)
Second switching about four seconds (in the 175minutes)
measurement? OFF Switching on
First switching about four seconds (in the 60minutes)
Second switching about four seconds (in the 175minutes)
measurement? ON Switching off
measurement? OFF Switching off
The reduction effect of formaldehyde by negative ions
Measurement result of measurement 1 and 2 is shown in the Fig. 2.
In the measurement 1 and 2, when we started measuring with the switch of negative ion generator off formaldehyde concentration in the desiccators raised up with time.
After 60 minutes measurements, we opened the cap of the desiccator’s necessity minimum and in the measurement 1, switched the negative ion generator on, and generate negative ions, and in the measurement 2, we just had the switching of the cap.
Then, in the measurement 1, formaldehyde concentration rapidly decreased, and after 175 minutes of measurement, it decreased 0.60ppm from the beginning point, but in the measurement 2, formaldehyde concentration kept increasing.
In the measurement 1, as we wanted to check the effect of negative ion, after the 175 minutes measurement, we opened the cap of desiccator’s necessity minimum, and switched the negative ion generator off.
As a result, with opening the cap of desiccators, formaldehyde concentration temporarily decreased, but as time passes, it increased again, and it increased till 60 minutes after switching the power off.
After that, every 60 minutes, we switched over negative ion generator, but we found out obvious correlation that when we switched it on and generated negative ion, formaldehyde concentration decreased, and when we switched it off it increased
The influence of the measurement for switching of desiccator
The measurement result of measurement 3 and 4 is shown in the Figure 3.
Both were in the condition of the desiccators cap closed, and in the measurement 3, negative ion generator’s was switched on from the beginning and in the measurement 4, it was switched off.
In the both of the measurements, formaldehyde concentration in the desiccator rose rapidly from the beginning, but in the measurement 3, after the 40 minutes, it started decreasing. This would be thought that till the 40 minutes after the measurement, formaldehyde and negative ions was filled in the desiccator and after that the mount of formaldehyde that decrease because of negative ions became bigger mount than the volatilization volume of formaldehyde, and this made to reduce the formaldehyde concentration.
On the other hand, measurement 4 kept rising after the beginning, and after 240 minutes, formaldehyde reached a saturation point, and could not find any concentration reduction.
Conclusion
When we use formaldehyde basic instrument, there is bit problem with the reliability of measured number, but in this study, the principal purpose is to check the successive comparison. So, we reported that it was obvious that there was the reduction effect of formaldehyde by negative ions through the experiment and measurement of closed system with using desiccator.
Additionally, through the open system experiment, we want to try to take indoor condition through the ion environments point of view.
Background materials
1)For example, NAKAMURA,Takashi, INUI,Hiroshi: about SHINKI and SHINKI System/ study of odor volume 31, number6/ 2000.11/p8-14
2) For example, Sasaki Hisao, Ryushi Tomoo, Japanese Society of Indoor Environment and Health: air negative ion dictionary/ Human & History / 2002
3)Seiichi Kimura, Masahiro Taniguchi: area of medicine air ion theory and practice /Nanzando/1938/p.106-108
And sometimes, we come across to the description that the rate of positive ion: negative ion=1:1.2 in the air today.
For example, Akiko Sugahara: secret of negative ion/PHP research institute /1998
4) For example in the note: 3 Mr. Kimura have described through the measurement in the Movie Theater and schools that places where people dense, especially the decrease of negative ion is fast and ion balance will get bad. ibid. p61
In addition, these studies have had the collaborative study with Ishikawa Laboratory and Sugawara Laboratories Inc. And thank you so much for Toshiba Carrier Corporation.
* Research student, Dept. of Architecture, Maebashi Institute of Technology
**Rindou Housing Co.,Ltd, M.Eng.
*** Assoc. Prof., Dept. of Architecture, Maebashi Institute of Technology, Dr.Eng.
**** Sugahara Institute, PhD.
