INDOOR CHEMICAL POLLUTION AND EMISSION RATES INVESTIGATED IN A REAL SIZED MODEL ROOM

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1 Proceedings: Indoor Air 22 INDOOR CHEMICAL POLLUTION AND EMISSION RATES INVESTIGATED IN A REAL SIZED MODEL ROOM S Tanabe 1, R Shirai 1, M Banno 1 and Y Asai 2 1 Department of Architecture, Waseda University, Japan 2 Nishimatsu Construction Co. Ltd. ABSTRACT Indoor air concentration of chemical pollutants in a real sized model room and their emission rates from floor, wall and ceiling were measured with FLEC to predict indoor concentration of chemical pollutants in long terms. For the factor affecting indoor concentration, the effect of temperature on indoor concentration and on emission rates of chemical pollutants from test pieces were examined. Just after remodeling, indoor concentration of formaldehyde and TVOC were 191 and 119 µg/m 3, which are above guideline values for VOCs by the Ministry of Health, Labor and Welfare, but they were decreased under the guideline after one month. Both indoor concentrations of the model room and emission rates of building materials were larger in higher temperature. Emission rates from floor materials were similar to those measured in the model room and decreased as time passed. INDEX TERMS FLEC, Real Sized Model Room, Indoor Concentration, Emission Rate INTRODUCTION In this study indoor air concentrations of aldehydes and VOCs were measured in a model room. Model room was first completed on August Measurements have been continued for three years until now. Result during the third year is reported here. Not only indoor air concentration of aldehydes and VOCs but also their emission rates from floor, wall, and ceiling were measured in the room by using FLEC. Building materials in the model room were also measured for comparisons in the laboratory under carefully controlled environment by FLEC. MEASUREMENT METHOD FLEC System Small cell chamber FLEC (Wolkoff, 1991) is used in this study. The FLEC can be used in laboratory or in field testing of e.g.: Floors, walls and ceilings. It is a robust cell made of solid, acid-resisting stainless steel with a large thermal capacity and with a negligible absorption capability. Purified air from gas cylinder is regulated at 5 %RH by air control unit. The air tightness between FLEC cell and surface of building materials are maintained by silicon, which emits little chemical pollutants. Air exchange rate of FLEC was set at.4 L/min and 686h -1. Sampling procedure Before measurement, FLEC cell was bake-ousted at 26 C in the oven, but dryer is used in the field measurements in order to remove background chemical pollutants from FLEC cell Contact author tanabe@waseda.jp 28

2 Proceedings: Indoor Air 22 itself. After it was cooled to the surrounding temperature, measurement was conducted. Indoor concentration of chemical pollutants in the model room was measured in the middle of the room and 1.2m above the floor. Outdoor concentration was measured at 2-5m away from the outside walls. Travel blank was taken at every measurement to subtract expected pollution of samplers. Sep-Pak DNPH silica cartridge was used for aldehydes with.3l/min and total 1L air was collected. Tenax TA tubes for VOCs with.1l/min and total 3.2 L. Aldehydes were analyzed by a HPLC and Gas Chromatography/Mass Spectrometry (GC/MS) was used for VOCs. The real sized model room Temperature, relative humidity, and air exchange rate of the model room are controlled by HVAC system. Temperature was regulated at 25 C and humidity was at 5%RH. Air exchange rate was controlled at.5h -1 by damper. Temperature of surfaces of floor, wall and ceiling were measured by thermocouples. Table 1 shows the outline of the model room and Table 2 also illustrates materials for interior of the model room. Figure 1 shows the perspective view of the model room. Symbols F and E are labeling of formaldehyde emission rate defined by Japanese Agricultural Standard (JAS) and Industrial Standard (JIS) by using desiccator s methods. These interior materials are typically used in the Japanese new constructed houses recent years. Table 1. Outline of Model Room Items Floor Area 8.78m 2 Wall Area (without windows and door) 23.m 2 Windows 5.22m 2 Door 1.62m 2 Volume 22.m 3 Interior Surface Area (Besides windows and door) 4.6m 2 Loading factor 1.85m 2 /m 3 Temperature control Air conditioner Air exchange rate.5h -1 Table 2. Interior Materials Flooring Wallcovering Ceiling Adhesive for wallcovering After remodeling (August 21) F co flooring / F co plywood / E plasterboard PVC (ISM) PVC (ISM) Low-formaldehyde starch Glass Air conditioning system Exhaust Opening Damper Window door A front view of preparation room for measurement Sampling hole Figure 1. Perspective view of the model room Preparation room for measurement 29

3 Proceedings: Indoor Air 22 EXPERIMENT IN REAL SIZED MODEL ROOM Measurement of indoor concentration of chemical pollutants The model room was remodeled in the middle of August 21. All interior materials were changed. Just after remodeling, experiments were started. Indoor concentration in the model room was measured at 2, 6, 9, 13, 28, 37, 72, and 125 days later after remodeling. Sampling conditions of indoor concentration and emission rates are shown in Table 3. Indoor air concentration were measured under two different conditions of ventilation and temperature. Air conditioner and ventilating system were stopped for condition A. However, they were operating for condition B and the room was controlled at 25 C and 5%RH. Table 3 Sampling conditions Sampler AC air flow rate AC temperature/humidity Aldehydes Sep-Pak DNPH-Silica Cartridges (short type) VOCs Tenax TA (2mg filled 6/8mesh).4L/min 25 C /5%RH Career gas Purified air Air flow rate.3l/min.1l/min Sampling time 33min 32min Sampling volume 1L 3.2L AC is an abbreviation of Air Control Figures 2 and 3 show indoor concentration of aldehydes and VOCs respectively. Measured indoor concentration of formaldehyde at 2nd day was 38µg/m 3 under condition A and 191 µg/m 3 for condition B. Both values were above guideline values for formaldehyde in Japan (1µg/m 3 ) and even after one month for condition A, it was still above it. In the beginning, the value of condition B was as half as that of condition A which was considered to be the effect by temperature and air exchange rate. For VOCs, indoor concentration of the 2nd day was 146µg/m 3 and 119µg/m 3 respectively under each condition but those were decreased as time passed. Main ingredients of VOCs were toluene and ethyl benzene Acetaldehyde Formaldehyde (L) Condition A (R) Condition B (L) Condition A (R) Condition B F F m Daysn *F: measurement failed Figure 2 Indoor concentration of aldehydes F Figure 3 Indoor concentration of VOCs The effect of temperature on indoor concentration The effect of temperature on indoor concentration was examined under air temperatures of 15, 25, and 3 C regulated by air conditioning system the model room. Figures 4 and 5 show indoor concentrations of formaldehyde and VOCs. For both formaldehyde and VOCs, indoor concentration was larger in higher temperature. Main ingredients of VOCs such as acetic acid and 2-(2-ethoxyethoxy) ethanol were also measured larger concentration in higher temperature. 21

4 Proceedings: Indoor Air Formaldehyde deg C 25deg C 3deg C Figure 4 Indoor concentration of formaldehyde 15deg C 25deg C 3degC Figure 5 Indoor concentration of VOCs Emission rate from each part in the model room Emission rates of chemical pollutants from floor, wall, and ceiling were measured by using FLEC. Temperature of surface of each part was also measured by thermocouples. Measurements were carried out at 1, 7, 14, 36, 71, 126 days later after remodeling. In the model room, temperature and air exchange rate were controlled at 25 C and.5h -1 respectively. Figures 6 and 7 show emission rates of formaldehyde and VOCs. For formaldehyde, emission rates of the first day from floor were lower than 46µg/m 2 h for F co value calculated by Inoue s equation (Inoue 1997, Tanabe 1998). On the other hand, emission rates from ceiling were very high. For VOCs, emission rates from ceiling were also very high in the beginning but it was decreased by 36 th day after remodeling. For wall and ceiling, finished materials were same but emission rates from wall and ceiling were very different. It was considered that higher temperature in measurement and air conditioning system set up in the ceiling affected the emission of chemical pollutants. By our previous experiments emission from floor was dominant, but this results show somewhat different Floor Wall Ceiling (L) FLoor (M) Wall (R) Ceiling Figure 6 Emission rates of formaldehyde Figure 7 Emission rates of VOCs EXPERIMENT IN LABORATORY Emission rates from test pieces In the laboratory, emission rates from test pieces of floor materials and wallcoverings were measured by using FLEC under the condition of 25 C and 5% RH. Floor materials were measured at 1, 2, 4, 8, and 15 days later after test pieces reached the laboratory and at 1, 2, 4, and 8 days for wallcoverings. Test pieces (25 25cm) which were same as used in the model room, were brought into the laboratory. Table 4 shows test pieces in detail. C and E of building materials were same types as used in the model room. 211

5 Proceedings: Indoor Air 22 Table 4 Test pieces A F C flooring F C1 Plywood E 1 Particle board Floor B F C flooring F C Plywood E 1 Particle board C F C flooring F C Plywood E Particle board D PVC Plasterboard Wall E PVC (ISM) Plasterboard and Ceiling F Paper Plasterboard G Cloth Plasterboard Figures 8-11 show emission rates of formaldehyde and VOCs from floor materials and wallcoverings. The value emitted from floor material C was 58.1µg/m 2 h at the first day but it was decreased by the 15 th day. After the 4 th day, emission rates from floor material C were similar to those measured in the model room. Emission rate from wallcovering E was around 25µg/m 2 h at the first day and even after 8 days it was not decreased. The difference of values measured both in the model room and laboratory were considered that the inside temperature were risen by solar radiation and it increased the emission of chemical pollutants Floor Materila A Floor Material B Floor Material C Figure 8 Formaldehyde from floor materials (L) Material A (M) Material B (R) Materila C Wall Material D Wall Material E Wall Material F Wall Material G Figure 9 Formaldehyde from wallcoverings From Left to Right Material D, E, F, G Figure 1 VOCs from floor materials Figure 11 VOCs from wallcoverings The effect of temperature on emission rates from test pieces The effect of temperature on emission rates from test pieces C and E were examined under the temperature of 15, 25, and 35 C. Temperature was carefully controlled in the incubator. Test pieces were kept in ADPAC (Tanabe et al. 2) for 48 hours for preparations to keep the test pieces at 5%RH. ADPAC is a small-scale chamber and it is possible to control temperature and humidity. After that, emission rate from test pieces were measured by using FLEC. Figures 12 and 13 show the effect of temperature on emission rates of formaldehyde and VOCs. For formaldehyde and VOCs, emission rates from test pieces were larger in higher temperature. For floor materials, the effect of temperature on emission rate of formaldehyde was observed but it was not for wallcoverings. For VOCs, emission rates from floor material and wallcovering were larger in higher temperature. Ingredients of VOCs such as ethylbenzene and benzophenone were also larger in higher temperature. 212

6 Proceedings: Indoor Air Floor Material C Floor Material E Emission Rate[µg/m2h] (L) Floor Material (R) Wall Material 15deg C 25deg C 35deg C 15deg C 25deg C 35deg C Figure 12 Formaldehyde from materials C and E Figure 13 VOCs from materials C and E PREDICTION OF INDOOR CONCENTRATION From the emission rate from each part measured in the model room, the indoor concentration of formaldehyde and TVOC were predicted. Figure 14 shows the result of formaldehyde and TVOC respectively. Just after remodeling, the predicted value of formaldehyde was lower than the measured value but they were close to the value after one month later. For TVOC, the measured value was much higher than the predicted one. This is because of high emission rates from ceiling Measured Value Predicted Value Measured Value Predicted Value Figure 14 Prediction of indoor concentrations of formaldehyde (left) and TVOC (right) CONCLUSIONS In a real sized model room, indoor concentration and emission rate from each part were measured by using FLEC to predict indoor concentration of chemical pollutants. Indoor concentration of formaldehyde and VOCs were high in the beginning but they were decreased as time passed. Formaldehyde and VOCs were mainly emitted from ceiling. Just after remodeling, the predicted value of formaldehyde was lower than the actual measurement but two values were closely resembled one month later. REFERENCES ASTM-D (1997), Standard Guide for Small-Scale Environmental Chamber Determinations of Organic Emissions From Indoor Materials/Products ENV Building products Determination of the emission of volatile organic compounds Part 2: Emission test cell method, Brussels, European Committee for Standardization. Funaki R, Shimada N, Tanabe S, Measurement of Aldehydes and VOCs emission rates using a small-scale chamber ADPAC, Healthy Building 2, pp Wolkoff P. et al, Filed and laboratory emission cell: FLEC, Proc. of IAQ91 Healthy Buildings, pp