Shin-Do Kim Jeong-Ho Kim ⋅ * ⋅ Jin-Soo Park Jeong-Joo Lee ⋅ 1) Department of Environmental Engineering, University of Seoul
1) Department of Environmental Health, Yong-In University
Abstract
Building materials are composed of very complex chemical compounds. The aims of this paper are to investigate the emission concentrations of indoor pollutants from new apartment house and the emission variation patterns during 75 days. The average value of total volatile organic compounds(TVOCs) con- centration was 3,768 ㎍ ㎥ / in five new apartments. Major VOCs included toluene, ethylbenzene, m,p-xylene and o-xylene. The average concentrations of each compound were measured as : benzene(58 / ), toluene ㎍ ㎥ (793 / ), ethylbenzene(438 / ), styrene(79 / ), m,p-xylene(1,210 / ), o-xylene(364 / ). The results ㎍ ㎥ ㎍ ㎥ ㎍ ㎥ ㎍ ㎥ ㎍ ㎥ indicated that the major VOCs from the new apartment were affected by building products such as on aromatic hydrocarbon compounds. TVOCs emission are characterized as high emission level at initial time (12,856 / ) and decreased through time. After a lapse of 75 days in sample house, TVOCs concentration ㎍ ㎥ decreased in about 20 times as compared with the initial concentration. The TVOCs emission profiles strongly depended on the generation mode and the concentration of the VOCs in building material.
Keywords ： Building materials, TVOCs(Total Volatile Organic Compounds), Emission concentration
1. Introduction
Most people in the developed world generally spend up to 90% of their time in the indoor environment, and that up to 60% of the worker works in the office(Baechler et al., 1991). Therefore, the indoor air quality is very important in public health and welfare, as the potential cost to society of poor IAQ is very high. Some investigators were reported that the indoor levels of air pollutants can be several hundred times higher than that of outdoor(Bluyssen et al., 1995; Samet and Spengler, 1991). Indoor pollution caused by volatile organic compounds (VOCs) is an important aspect of IAQ which raises particular concern since many organic indoor pollutants are either known, or are suspected to be allergic, carcinogenic, neurotoxic, immunotoxic, irritant or indicative of sick building syndrome.
Determining the major sources of VOCs is critically important for mitigating IAQ problems in indoor environments. Newly constructed building can emit a variety of VOCs. Therefore, it is important to accurately characterize VOCs emitted from building
materials.
At present, the studies of the emission effect are mainly conducted by experiments using small-scale, large-scale environmental test. Environmental tests(field study) are important tools for characterizing organic emission from consumer and construction products and evaluating their potential impact on indoor air quality. The aims of this paper are (1) to investigate emission concentration from new apartment house in Seoul, (2) to estimate of the emission concentration variation from finishing construction to moving into the new apartment.
2. Materials and Methods
2.1 Sampling sites
We investigated the VOCs concentration emitted from new apartment house in metropolitan area. The specifics of five apartment house are as Table 1.
measurement sites were determined that living room and the largest bedroom in indoor and outdoor located in the fresh air intake stream would provide
Class Top floor
Target measuring floor
Outdoor floor
Acreage (p'yong)
Living room Bedroom Time elapsed after finishing construction
Upper Middle Lower Area
( ) ㎡
Volume ( ) ㎥
Area ( ) ㎡
Volume ( ) ㎥ S1
S2 S3 S4 S5
23 24 20 18 38
23 23 20 16 36
10 12 15 10 19
2 4 4 2 7
1 1 1 1 1
33 32 33 32 67
26.2 25.7 27.9 23.9 38.1
60.3 59.1 64.2 55.0 89.5
14.7 17.1 15.2 17.6 26.8
33.8 39.3 35.0 40.5 63.0
2 month 2 month 1.5 month
1 month
2 month
a reasonable spatial distribution of measurement at breathing zone.
2.2 Sample house
Building materials used in this study were selected to represent major groups of building materials(Table 2). The experiments were performed in mock-up house of newly constructed building(so call, sample house). Sample house were consist of several build- ing materials and has a floor space of 105.7856 ㎡ (32 p'yong). A design of a sample house was based on a commercial standard design in Fig. 1.
The design of the VOCs emission house had three rooms, two bathroom, one living room, one kitchen and one dining room. It was located at a newly developing area in Seoul. An recovery heating system was used to controled the room temperature within steady state. The major sources of VOCs in indoor air are wet construction products(paints, adhesives, and sealants) in new buildings and a mixture of wet household products but, there was not used the wet construction products. Only dry materials used in this sample house, while paper a wallpaper with starch.
For the long-term test of sample house, VOCs samples were collected at 3, 9, 13, 20, 39, 63, 73, 75 days in time series, respectively.
2.3 VOCs Sampling and Analysis
The relative humidity and temperature in the sample house were measured by using high accuracy thermo-hygrometers(RS 11, ESPEC, USA). Indoor air
Structure Building materials
Floor Side wall Roof
Base Concrete Brick
Concrete Concrete
Inner part Panel heating Heat insulator Gypsum board
Ceiling frame Gypsum board Finish interior Wooden floor
(pressed wood) Wallpaper Wallpaper
KD
R2 L R1
R3
B1
B2
sampling was conducted under stable condition(20±
2 , 50±10%) and performed taking into general ℃ aspects of sampling strategy as ISO 16000(Part 5:
Sampling strategy for volatile organic compounds).
An object of this study were five newly produced apartment house at Seoul metropolitan area. Analysis of VOCs were performed as ISO 16000. Indoor air sampling was conducted under condition when VOCs
concentrations have reached steady-state conditions.
As such, the protocol involved opening the all door and side window to let fresh air in from 9:00 till 9:30 and closing all door and side window contact with ambient from 9:30 till the end of sampling and sam- pling from 14:30 p.m till 15:30 p.m in the afternoon.
VOCs were first enriched in a preconditioned single sorbent(TENAX TA) stainless steel tube(1/4
Benzene
Ethyl Benzene
Xylene
Toluene
Items Contents
Specifications GC-MS, ATD 400 Column
Perkinelmer, U.S.A BP-1(0.32mm×60m×0.5 ) ㎛
Carrier Gas and Flow He(99.999%). 1 2 /min ㎖
Temperature Conditions
Initial Temperature Increasing Grade Final Temperature
40 ℃ (10min) 5 /min ℃ 230 (3min) ℃ MS Conditions Interface Temperature
Ion source Temperature Mode
Electron energy Detection mode
200℃
200℃
EI(electron ion) 70ev
TIC(Scan)
inch OD×3.5 inch length). Tubes were initially conditioned by flushing helium for a period of 30 min at 350 ℃ with flow-rate of 30 ml min-1. They were then sealed with Swagelock fittings and polyte- trafluoroethylene(PTFE) ferrules preventing contami- nation prior to use. During measurements, 3 sampling channels draw same volumes of air(1.5 L) for each of the floor(lounge, bedroom and outdoor) with micro air pump(Gillain, USA). A total of 27 tubes were collected on each newly building. To account for any flow drift, flow-rates were measured before and after sampling using a digital airflow meter(Alltech, USA) and then averaged. All samples were then sealed airtight, placed in cool containers and transported back to the laboratory.
Analysis condition was showed in Table 3. Total ion chromatogram for a sample was integrated over a retention time window rang bounded by n-hexane and n-hexadecane to calculate the TVOCs concentration.
Concentrations for all compounds and VOCs were evaluated using multi-point calibration from the external standards provided by EPA TO-14 standard gases(Supelco. USA) in Fig. 2.
2.4 TVOCs emission Factor
The role of source modeling is to interpret the concentration data and convert them to emission rates, which can then be used by indoor air quality models(ECA, 1991; Guo and Tichenor, 1997; Guo, 2002; Guo et al., 2003; Kim et al., 2004). Source modeling provides a link between source testing and IAQ modeling. Eq. (1) is the simplest IAQ model based on the principle of mass conservation.
(1)
Where,
is the mass conversion(mass time -1 ), the source emission(mass time -1 ), the penetration factor for pollutant from ambient air(fractional), the air exchange flow rate for building(length 3 time -1 ), the concentration in ambient air(mass length -3 ), the concentration in air(mass length -3 ). The indoor source term R in Eq.
(1) is often represented by a mathematical expression known as the indoor emission source model. Model for building materials are very difficult to model because the emissions are often controlled by mol- ecular diffusion in the materials. The IAQ model used data on source strength, air exchange and room size. This model can also be used to compare meas- urement of pollutant concentrations in building with model predictions based on emission parameters measured in the sample house. Where air quality in a building was to be evaluated, the actual values were inserted in the IAQ model(Fellin and Otson, 1993).
Emission rates of TVOCs for the sample house were evaluated Eq.(2). and is derived equation employed has been widely used(Tuomainen et al., 2001; Kim et al., 2004). Where, is the area specific emission rates( / hr), ㎍ ㎡․ the volume of space( ), ㎥ the air exchange rate, A the floor area of space( ), ㎡ the indoor concentration( / ). ㎍ ㎥
(2)
2.5 Air exchange rate
Air exchange rates were estimated using the
method described by Reindl(1997) and Feher and Ambs(1997). It was performed using Carbon Dioxide(CO 2 ) as a tracer gas and observing the decay in concentration at the center of the bedroom.
Measurements of CO 2 were made using an infrared gas analyser(CO/CO 2 meter, Sibata, Japan) in absolute measurement mode and scaled 0 5,000 ppm. – The analyser inlet was plumbed via 1/4 inch tubing to the center of the room 1.2 m above the floor.
Ambient CO 2 levels were measured 2 m above the ground. In this study, was calculated as Eq.
(3) and presented in Table 4.
(3)
was initial saturated concentration of CO 2 in indoor. was outdoor and was concentration of CO 2 after 4 hour in time series.
3. Results and Discussions
3.1 TVOCs emissions from new apartment house
TVOCs Concentrations
To investigate of VOCs emission from new
apartment house before moving in, we are carried out to VOCs measuring for the five new apartment house located in Seoul. Table 5 was represented the TVOCs concentrations for the five new apartment house and the variations of TVOCs in measured in there. The TVOCs concentrations emitted from the five new apartment house appears to have the highest concentrations(3,768 / ) compared to the WHO ㎍ ㎥ (300 / ) ㎍ ㎥ recommendation level. The arithmetic mean of all measurement sites was 3,768 / ㎍ ㎥ and 3,890 / ㎍ ㎥ in median. The findings indicated that the concentrations of all new building in this research are consistently very much higher than the recommended value of WHO, about 12 times.
Brown et al. (1994) found that mean TVOCs concentrations were approximately 4,000 ㎍ ㎥ / in new buildings. Iwata et al.(2003), field measurements on indoor air quality were conducted in newly-built houses, found that TVOCs show higher level, 2,500-30,000 / ㎍ ㎥ than Japan guidelines, 400 / ㎍ ㎥ (tentative value). Recently, the closure of natural openings of buildings for energy saving purpose, the use of untested new construction materials, the type of building materials as well as the poor air exchange affect the indoor air quality. These high TVOCs
Class Measurement Parameter
, ppm
, ppm , ppm , hr-1
S1 S2 S3 S4 S5
3,003 3,005 3,012 3,008 3,002
412 421 397 405 394
1,324 1,380 1,384 1,312 1,317
0.209
0.198
0.195
0.211
0.208
concentrations also indicate the notice of a pollution prevention for indoor exposure to TVOCs in the new apartment house.
In S4 with one month before moving in appears to have the highest concentrations(4,890 / ) compared ㎍ ㎥ to the rest of the other sites. Specific emission rates(SER, / hr) for newly building, also S4. has ㎍ ㎡․
highest emissions at 824 ㎍ ㎡․ / hr. S4 Showed higher TVOCs value than the others because S4 has been constructed these 30 days after finishing construction, while the rest was 45 days or more. Most VOC related comfort or health problems can be expected to be associated only with the first few months of occupancy or after refurbishment. A tentative recommended action level (3,000 / ㎍ ㎥) and tentative levels of concern (200-300 / ㎍ ㎥) for the amount of
TVOCs have been suggested. This suggests that the TVOCs concentrations are acceptable 3 months after completion of the low VOCs emission house (Molhave, 1991). The health and comfort conse- quences of indoor concentrations of TVOCs may be assessed using the above recommendations.
VOCs Individual Concentrations
Identified components and non-identified(NI) VOCs were showed in Fig. 3, box plot with 5th-95th percentile. Box plots graph data as a box representing statistical values. The boundary of the box closest to zero indicates the 25th percentile, a line within the box marks the median, and the boundary of the box farthest from zero indicates the 75th percentile.
Whiskers left and right the box indicate the 10th and 90th percentiles. Major VOCs, including toluene,
Items S1
2month S2
2month S3
1.5 month S4
1 month S5
2 month Overall
Indoor
Sample number Temperature, ℃ Relative Humidity, % TVOCs Mean, ㎍ ㎥ / TVOCs Median, ㎍ ㎥ / TVOCs Max., ㎍ ㎥ / TVOCs Min., ㎍ ㎥ / TVOCs S.D., ㎍ ㎥ / ACH, hr-1
TVOCs SER, ㎍ ㎡․ / hr
18 18.0 72.7 4,100 4,373 5,483 1,762 1,388 0.239 179
18 26.6 77.7 3,847 4,054 5,141 2,416 1,064 0.198 124
18 26.6 70.9 3,285 2,615 5,587 2,187 1,383 0.195 329
18 27.2 66.5 4,890 4,816 6,222 3,780 824 0.211
421
18 28.3 77.0 2,720 2,807 3,584 1,279 811 0.208
189
90 18.00
73.0 3,768 3,890 6,222 1,279 1,284 0.210 248
Outdoor
Sample number Temperature, ℃ Relative Humidity, % TVOCs Mean, ㎍ ㎥ /
9 22.6 66.4 2,505
9 26.9 73.9 2,740
9 25.3 64.0 360
9 27.5 70.1 1,150
9 28.9 72.0 1,078
40
9.00
69.3
1,567
ethylbenzene, m,p-xylene and o-xylene, were indicated. The average concentrations were benzene 58 / , toluene 793 / , ethylbenzene 438 / , ㎍ ㎥ ㎍ ㎥ ㎍ ㎥ styrene 79 / , m,p-xylene 1,210 / , o-xylene ㎍ ㎥ ㎍ ㎥ 364 / , respectively. They were commonly found ㎍ ㎥ in petroleum-related products. The most abundant VOCs was m,p-xylene since it had a higher vapour pressure among the VOCs identified. The higher the vapour pressure, the higher the rate of evaporation and thus the more amount of VOCs emitted. The results indicated that the major VOCs from the newly building were effected using by building products based on aromatic hydrocarbon compounds. MOE (Ministry of Environment, Korea, 2005) has amended the law for indoor air management, and prepared the national action plan recently. The constructors of new apartments with over 100 units are enforced to measure 7 toxic substances (formaldehyde and VOCs
including benzene, toluene, ethyl benzene, xylene, 1&4 dichlorobenzene, and styrene) in prior to the moving in of tenants. However, there is include out individual VOCs concentration. The guidelines in Japan are 100 / ㎍ ㎥ for toluene, 870 / ㎍ ㎥ for xylenes, 3,800 / ㎍ ㎥ for ethylbenzene, 240 / ㎍ ㎥ for styrene(Iwata et al., 2003). Toluene and xylenes show higher values than guidelines, because of sample house is used wood products in floor. The compo- nent of Benzene, xylene, toluene and ethylbenzene were mainly source in wood products, floor materials and furnishings(John et al., 2000). These dry mater0 ials such as pressed-wood products, emissions are likely to continue at low levels for longer periods.
3.2 Evaluation for TVOCs decay level in sample house by time series
It has been reported that since building materials
Concentration[µg/m
3]
0 1000 2000 3000 4000 5000 6000 7000
0 1000 2000 3000 4000 5000 6000 7000
hexane
1,2-dichloroethane benzene
carbontetrachloroide 1,2-dichloropropane cis-1,3-dichloro-1-p 1,2-dibromoethane tetrachloroethane trichloroethane chlorobenzene ethybenzene m,p-xylene o-xylene toluene stylene
1,3,5-trimethylbenzene
1,2,4-trimethylbenzene m-dichlorobenzene p-dichlorobenzene o-dichlorobenzene TVOCs NI
represent the largest surfaces in the indoor environment, they are the largest contributors of VOCs. The evaluation for TVOCs decay level in sample house were performed in mock-up house made of newly produced building. Figure 4 was represent the temporal variations of TVOCs concentration for the applied materials and products area measured in the sample house. Room temperature in sample house was set in 20 ℃ by heat recovery system. Actual room temperature was measured about 18-23 . Average value of relative ℃ humidity was about 32% during test period. The TVOCs concentration were initially increased to a maximum value with 3 days, 12,856 / ㎍ ㎥ and then decreased to a minimum value with 75 days, 608 ㎍ /
.
㎥ Englund and Harderup(1996) measured the indoor air VOCs levels during the first year of a new three-story building. The initial levels of TVOCs were between 1,497 and 3,855 / ㎍ ㎥. After 3 months, the concentrations of TVOCs decreased to 255 390 – ㎍ /㎥. TVOCs emission rates and concentrations decrease with time. The results indicated that the TVOCs measured did release certain amount of VOCs but the levels of TVOCs emitted were decreased within 13 days.
To estimating of these emission patterns, Chang and Guo(1992) suggested two first-order decay terms.
By convention, the first term in Eq. (4) represents the fast emissions and the second term, slow emission.
Where, is the emission factor, and the initial emission factor, and the first-order decay rate constant, the time.
(4) The line in Fig. 4 expressed was exponential decay equation value well with measured (
, R 2 = 0.999). In this study, TVOCs concentrations emission rates from new sample house changed double- exponentially with time. The TVOCs emission profiles strongly depended on the generation mode and the concentration of the VOCs within building material. VOCs is a slow and continuous process and may be source of low-level, slow decay releases.
These emission mechanisms can be generally characterized into surface emission and in-material transport plus surface emission(Guo et al., 2004; Kim et al., 2004).
4. Summary
VOCs associated with paints, varnishes, adhesives, carpets, furniture and other materials are likely to be a major cause of health complaints associated with indoor air in new buildings. VOCs sources were identified and quantified in five newly apartment house in Seoul and to estimate of the emission concentration from building materials, performed the sample house to investigate the TVOCs emission throughout 75 days. Average value of TVOCs concentration was 3,768 ㎍ ㎥ / in five newly buildings. Major VOCs, including toluene, ethyl- benzene, m,p-xylene and o-xylene, were indicated.
The average concentrations were benzene 58 / , ㎍ ㎥
toluene 793 / , ethylbenzene 438 / , styrene 79 ㎍ ㎥ ㎍ ㎥
/ , m,p-xylene 1,210 / , o-xylene 364 / ,
㎍ ㎥ ㎍ ㎥ ㎍ ㎥
respectively. TVOCs emission characteristics are high emission level at initial time, 12,856 ㎍ ㎥ / and decreased in course of time. After a lapse of 75 days in sample house, TVOCs concentration was decreased in about 20 times compared with initial concentration.
Newly Building emitted high concentration volatile organic compound(VOCs) and VOCs emission characteristic are high emission level at initial time and decreased in course of time. Initial value was higher the published recommend values. TVOCs concentrations of approximately 5 ㎎ ㎥ / are con- sidered sufficient to cause sick building symptoms, particularly mucous membrane irritation(Mo/lhave et al., 1986). Acceptable TVOCs concentrations for health and comfort consequences in new building, officially corresponding emission standards for VOCs do not yet exist.
To reduce exposure to VOCs in indoor air, there are several way. Aims to accelerate the curing of materials by accelerating air exchange rate in the
house to allow faster escape of the VOCs. The building materials used in the house were all tested in environmental chambers to ensure that they were low VOCs emission materials(Guo et al., 2003). TVOCs emission rates and concentrations decrease with time.
VOCs emitted by the building materials decreased to a stable state within approximately a year. For the purpose of controlling TVOCs concentration in new building, it is necessary to know their emission characteristics and research will focus on the emission rate from individual building material with environmental chamber test during the long period.
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신축아파트에서 발생하는 TVOC의 방출특성
