A Study on the Correlation Nature of Air Ions and Formaldehyde
In Opened System
Experimental Study on Air Ions in Environment Part 2
Akio KENMOCHI, Miho NAKAZATO, Tsuneo ISHIKAWA
Akiko SUGAHARA
Air ion air quality negative ion
Positive ion
Formaldehyde indoor air contamination
First
In this study, we are based on the presupposition that gaseous chemical material that arise from dirt, dusts and building materials are not the real identity of positive ion 1), and our aim is to verify the conjugation of negative ion as countermeasure technique of indoor air contamination, and in the second of the study, we had the measurement along the following lines in order to clear up the possibility of formaldehyde reduction effect by negative ion in open system(the size of 8 tatami mats)
2. Measurement method
We leased two rooms that have the same room layout, the same east-facing neighboring rooms(measuring room area 10.4 ?) built seven months ago, and nobody have lived there.
And to the one room, we put an air conditioner that have negative ion generating function (corona discharge system) for the measurement, and to the other room, we used the normal air conditioner that have been already used there, and measured air ion concentration and formaldehyde concentration from both of the rooms.
We also measured temperature and humidity in the same time for the ambient inspection.
The measurement for the both negative and positive ions, we arranged two instruments, but the numbers have varied, so we decided to take the average of the two instruments after measuring ten minutes of both negative and positive ions.
So, we measured two rooms with taking 30minutes time lag.
And for the formaldehyde concentration measurement, we had the measurement with using simple measuring instrument in the same time with ionic concentration measurement, but indicating reliability, based on the manual of the Ministry of Health, Labor and Welfare, we adopted 24hours passive sampler (the average amount of the two)
The chart in the next page is based on the result of the passive sampler.
Measuring method is shown to the Figure 1, measuring outline to the Table 1, and the situation of measurement room for the Figure 2.
We had the measurement twice a week from the end of October year 2002, and we recorded graphically successive comparison.
At the end of October, temperature declined, and formaldehyde concentration declined as well, and from November 1st, we switched air conditioner to heater operation and raised the room temperature, and humidity to about 55%, and put Fcplywood that is coated by glue as a source of contamination, and had the same type of measurement. However, at the moment we will mainly consider about the measurement to October.
measurement result consideration
There is four graphs shown from the numbers that were got from the measurement to the right; indoor humidity/temperature (Figure 3), air ion level (Figure 4), air ion ratio (Figure 5), formaldehyde air concentration (Figure 6).
We ordered MSDS, and we obtained the architectural material information to a maximum extent (Table 1), but there were no particular materials that might radiate formaldehyde, but still it did not drop below 50g in September.
Also, though the specifications might be exactly the same, we can not think that the craftsman used the same amount of glue, so the absolute amount of formaldehyde in each room will not be the same.
We also made the graph that is set default value at one hundred, but in Figure 6, the measured number is directly plotted.
Formaldehyde aerial concentration in the Figure is compensated to 25 RH50% by the Inoue expression 2).
If there is formaldehyde reduction effect, in the room 102 where negative ion have generated, there must have faster fall off of formaldehyde concentration than the room 103.
Actually, I would like to stress that the air ion balance was extremely good in the room 102 where they had big mount of negative ion (Figure 4, 5).
However, we could not find out the significant differences to the both of the rooms (Figure 6)formaldehyde concentration difference, so we stop short of acknowledging the mutual relation between air ion concentration or air ion ratio and formaldehyde concentration.
Totally graph is showing the variation of moving downward; rather showing the influence of temperature and humidity (Figure 3) is bigger than the negative ion concentration.
So, though the formaldehyde concentration of both of the room is the numerical number of temperature-corrected, it is just showing the given correlative relationship when room air temperature is high or when it has humidified, it is high (Figure3, 6).
4. conclusion
We could not proof at the experiment of open system about the reduction effect of formaldehyde concentration in the air from negative ion generation.
However, this does not instantly chalk that there is no reduction effect inherently.
First of all, we need to examine the differences of the prerequisites of measurement like negative ion generating system and concentration in the desiccators and in the living rooms, and formaldehyde generation source and its absolute quantity, moreover the air leakage efficiency of the space.
Second, in the living room, the concentration distribution measuring method in perpendicularity / horizontal direction is worth considering, because there might be the negative ion and formaldehyde adsorbed on the wall and on the ceiling surface.
The more, in the real-life, we should think that negative ion will be generated all the time, so the measurement in that kind of situation, and the concentration measurement of negative ion and formaldehyde in the same time is worth trying.
Look at these things in, and we will have measurement continuously and we would want to try to establish the structured model that shows the capability of removal and reduction of the gaseous toxic chemical compounds by negative ions.
The lists of references
1 for example, Akiko Sugahara the secret of negative ion / PHP Institute / 1998/p.29
2)Akio Inoue: guidelines countermeasures of formaldehyde atmospheric concentrations / wood industry /Vol.52,No1/ 1997/p.9-14 This study have created from a collaboration of Ishikawa Laboratory and Sugahara Institute. And let me express my gratitude to the corporation of the people in Toshiba Carrier Corporation.
* Rindou Housing Co.,Ltd, M.Eng .
** Research student., Dept. of Architecture, Maebashi Institute of Technology
*** Assoc. Prof., Dept. of Architecture, Maebashi Institute of Technology, Dr.Eng.
**** Sugahara Institute, PhD.
