Determination of total volatile organic compound ... - Springer Link

Original paper

Clean Prod Processes 3 (2001) 42±48 Ó Springer-Verlag 2001

Determination of total volatile organic compound emissions from furniture polishes Hai Guo, Frank Murray

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Furniture polish may contain one or more of the following substances: nitrobenzene, petroleum distillates, phenol, and diethylene glycol (Sack and Steele 1991). The health dangers most often associated with the use of furniture polish are inhalation of fumes or vapours and skin absorption. The symptoms include nose and throat irritation, eye damage, liver and kidney problems, birth defects, lung tissue damage, and nervous disorders (HWRIC 1984). Studies on the emissions of volatile organic compounds (VOCs) from furniture polishes have been reported in European countries and the USA (Tichenor 1987; Anguenot et al. 1990; Colombo et al. 1990). Most studies have focused on the characteristics of VOC emissions from furniture polishes. However, a study by Anguenot et al. (1990) evaluated the indoor air quality resulting from the use of furniture polish by using a simpli®ed model. In Mediterranean countries and Australia where the climate is warm and house ventilation rates are high, limited data Introduction Polishes are chemicals designed to shine furniture. There are available on the emissions of VOCs from furniture polish sources to predict indoor air quality. In particular, are three general types of commercial furniture polish: no study has investigated the in¯uence of VOCs emitted solvents, emulsions, and aerosol sprays. Each type contains speci®c chemicals that aid in the application of the from furniture polishes on indoor air quality under these wax or oil to the furniture surface. Solvent polishes use an climate conditions. A measurement of total volatile organic compounds organic solvent to dissolve the oil or wax to ease the application. In emulsion polishes the oil or wax is suspended (TVOCs) is frequently used to assess indoor air quality, because the interpretation of one single parameter is in a liquid, usually water. Aerosol sprays are solvent or simpler and faster than the interpretation of the concenemulsion type packed under pressure (NSEC 1991). trations of several dozens of VOCs typically detected indoors. The concept can be useful in many cases where there is some knowledge about the VOC pro®le, e.g. for Received: 15 December 2000 / Accepted: 19 December 2000 comparison of similar material samples and for studies of the time dependence of source strength (Englund and H. Guo (&) Harderup 1996). Non-speciated TVOC measurements may School of Environmental Science, be useful for monitoring the effectiveness of physical Division of Science and Engineering, Murdoch University, Perth, WA 6150, Australia changes in a building. In this case, the calibration gas e-mail: [email protected] chosen is critical in determining whether the TVOCs is a good indicator of the real pollutant level (Niu et al. 1996). F. Murray The aim of this study was to investigate the emissions of School of Environmental Science, TVOCs from different types of furniture polishes. An enDivision of Science and Engineering, vironmental test chamber with controlled climate condiMurdoch University, Perth, WA 6150, Australia tions was used to investigate the time dependence of Present address: TVOC emissions from three furniture polishes. These were H. Guo selected as the most representative products available on Nelson Institute of Environmental Medicine, the Australian market. TVOC emissions from aerosol School of Medicine, New York University, spray, solvent and emulsion furniture polishes were 57 Old Forge Road, Tuxedo, NY 10987, USA compared. To develop models to obtain emission parameters for The contributions of Kelvin Maybury are gratefully representative furniture polishes was another objective of acknowledged. Abstract In this study, an environmental test chamber with controlled temperature, relative humidity, and air¯ow rate was developed to evaluate emissions of total volatile organic compounds (TVOCs) from three different kinds of furniture polish. The time dependence of TVOC concentrations produced from the emissions of furniture polish products in the chamber was tested. TVOC emissions from each furniture polish were compared. The main volatile organic compounds emitted from each polish were identi®ed by gas chromatography/mass spectrometry. A double-exponential equation was developed to evaluate the characteristics of emissions of TVOCs from these furniture polish products. With this double-exponential model, the physical processes of TVOC emissions can be explained. A variety of emission parameters can be calculated. These emission parameters could be used to estimate real indoor TVOC concentrations.

H. Guo, F. Murray: Determination of total volatile organic compound emissions from furniture polishes

this study. These chamber parameters, associated with environmental factors, e.g. house ventilation rates and house size, were then used to simulate real indoor TVOC concentrations in Mediterranean climates. A double-exponential model was therefore developed in order to evaluate the potential of VOC emissions from furniture polishes.

Materials and methods After investigation of the market sales information available, three typical furniture polishes were purchased. One was an aerosol spray, one was an emulsion polish, and one was a solvent polish (Table 1). A preliminary evaluation of the polishes was performed to guide selection of appropriate test strategies and analytical techniques. This evaluation was conducted to obtain emission information on the polishes. These tests were conducted using headspace analyses. Portions of polishes were placed in 250-ml clean glass vessels ®tted with septum top screw caps. Then 1±5 ml of air from above the sample was drawn into the syringe from the vessel. The sample was then injected onto the gas chromatography (GC) column. All three products were tested in a small glass chamber (volume: 13.56 l) with one inlet and two outlets. The chamber was placed in the temperature-controlled incubator cabinet. The relative humidity of the chamber air was controlled by bubbling a portion of the air stream through deionised water at a controlled temperature (in a water bath). A puri®ed air¯ow of 200 ml/min was passed through the chamber. The atmosphere in the chamber was mixed by a small fan suspended from the ceiling of the chamber. To determine whether the air in the chamber was adequately mixed, an inert tracer gas (SF6) was blended with the inlet air at constant concentration and ¯ow, and then the concentration in the chamber outlet was measured over time. The chamber was shown to be well mixed since the plot of chamber concentration against time closely followed the following theoretical curve:

Leaks were checked by measuring the air¯ow rate simultaneously at the inlet and at the outlet ports to ensure that they were the same value. To avoid sink effects, the material used to construct a chamber must be non-adsorbent, chemically inert, and have a smooth surface. In this project, glass was used, and results showed that sinks could be ignored, consistent with COST (1991). Before testing each furniture polish, one chamber blank sample was analysed by GC/¯ame ionisation detection (GC/FID, Model 3700, Varian Inc., 3120 Hansen Way, Palo Alto, Calif.) to ensure the TVOC concentration in the chamber was below 5 lg/m3. Otherwise, the chamber was cleaned again until it was quali®ed. To obtain speci®c and clear TVOC emissions data, the furniture polish samples were prepared by placing an amount of polish into a 10-ml glass vial with an emission surface area of 3.14 cm2 and thickness of 2)4 mm. The aerosol spray furniture polish was sprayed directly from the can into the vial and the vial was immediately covered tightly with a cap. The sample was then weighed (Model 1801, Sartorius GmbH Gottingen, Germany) and immediately placed in the chamber (the vial containing aerosol spray polish was uncovered immediately before it was placed in the chamber). Sample weight loss was determined by weight difference to the nearest 0.0001 g. The experimental conditions for all emission measurements in the chamber were as follows: Temperature Relative humidity Air exchange rate Chamber loading Support material

23 °C1 °C 50% 5% 0.885 h)1 0.00023 m2/m3 Glass

During the high emission period of the emission test, air sample volumes of 1000 ml were collected at a sampling rate of 200 ml/min to prevent overloading of the concentration column of the purge and trap unit (Sanchez et al. 1987). The air sample volume was increased to a maximum of 1500 ml as the emission rate decreased. VOCs were Nt collected using adsorption tubes (Tenax-GR, 80/100 C C0 1 e mesh). Immediately after sampling the tubes were tightly sealed and analysed by GC/FID. Samples were collected at where C chamber concentration, mg/m3; C0 inlet progressively increasing intervals (Figs. 1±3). The GC/FID concentration, mg/m3; N air exchange rate, h)1; N Q/V, where Q ¯ow rate through the chamber, m3/h, apparatus was equipped with a modi®ed thermal desorption cold trap injector. The samples were thermo-desorbed and V chamber volume, m3; t time, h. Table 1. The furniture polishes selected for chamber testing Product

Main ingredienta Solvent type Application a

Solvent polish

Aerosol spray polish

Emulsion polish

Natural oil, toluene, benzene, xylene isomers, styrene, methylisocyanate, limonene, camphene Hydrocarbons Oiled or varnished wood, cork or stone surface, furniture, ¯oors, counter tops

Wax

Wax, toluene, benzene, xylene isomers, styrene, limonene, camphene

Hydrocarbon

Hydrocarbons

Data obtained from manufacturers

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Clean Prod Processes 3 (2001)

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Fig. 1. The TVOC concentration and emission rate from aerosol spray furniture polish with time after application

Fig. 2. The TVOC concentration and emission rate from emulsion polish with time after application

Fig. 3. The TVOC concentration and emission rate from solvent furniture polish with time after application

into the GC/FID instrument for TVOC quanti®cation. A ®lm capillary (Alltech ECONO-CAP SE-54, 30 m ´ 0.53 mm ID ´ 1.2 lm) was employed for the separation of VOCs. The adsorbed sample was cryotrapped at )80 °C and injected into the GC apparatus. The temperature program was initially set at 40 °C for 5 min, then increased at a rate of 5 °C/min, and ®nally set at 200 °C for 3 min. The injection temperature was 200 °C; the temperature of detector was 230 °C. The TVOC concentration was calculated from the total area of the FID chromatogram using a toluene response factor.

The change in TVOC concentrations from each polish sample with time was measured for approximately 24 h, as emission rates were adequately described and predictable by this time. A series of toluene standards in methanol from 50 to 500 lg/ml were prepared. A calibration curve was established every month by direct injection (0.5 ll) of the toluene standards. A 0.1 ll portion of standard toluene solution was injected into the adsorption tubes before thermal desorption as a quality control measure. 10% of air samples were replicated for the three furniture polishes for each sample analysis run.


To identify VOCs emitted from samples, a portion of polish was placed in a 250-ml modi®ed glass vessel. The vessel had one inlet and one outlet ®tted with septum screw caps. To avoid contamination, the vessel was puri®ed by helium for 30 min before being sealed tightly. The glass vessel was then placed in an oven at 45 °C for 24 h to allow for evaporation of VOCs. The air in the vessel was purged with helium and a 1000-ml air sample was drawn through a sampling train composed of components that regulated the rate and duration of sampling into a TEDLAR bag (Supelco Inc., Supelco Park, Bellefonte, Pa.). Subsequent analysis of the contents of the bags was performed by GC/mass spectrometry (MS). A portion of the air sample in the bag was sampled using a mass ¯ow controller to draw a known volume of gas through a cryogenic trap cooled to )150 °C. The trap was then rapidly heated to +180 °C and the trapped VOCs were transferred to a capillary GC column (J&W DB-1, 60 m ´ 0.32 mm, 1 lm ®lm). The GC oven was temperature programmed and the separated VOCs were detected by MS (Varian Inc., 3120 Hansen Way, Palo Alto, Calif.). The GC/MS system was operated in the full scan mode and compound identi®cation was achieved by mass spectral library search of the NIST/EPA/NIH library. The emission rates of TVOCs from the polish products were calculated using a double-exponential model (Wilkes et al. 1996; Chang et al. 1997):

where ± L material loading (m2/m3) ± N Q/V air exchange rate (h)1). The double-exponential model was used to analyse the chamber data using a non-linear least-squares best ®t routine (MacCurveFit 1995 program). The four emission parameters E10, E20, k1, and k2 are then obtained. The quality of the least-squares ®t and the uncertainties in the coef®cients are assessed automatically by the MacCurveFit program (MacCurveFit 1995). The MacCurveFit program uses an exponential peeling procedure to calculate the best estimates of the emission parameters (Serber and Wild 1989; MacCurveFit 1995; Mùlhave et al. 1995). With known emission parameters from indoor sources, the TVOC concentrations under speci®c material loading (L) and air exchange rate (N) can be simulated.

Results and discussions

Chamber testing Figures 1±3 showed the measured TVOC concentration± time pro®les. In addition, the modelled TVOC concentration and emission rate with time were included. The measured TVOC concentration resulting from the aerosol spray furniture polish increased rapidly to the maximum of 4.25 mg/m3 within 2 h and decreased to 28% within 7.5 h and to 0.7% of the maximum within 24 h Et E1 E2 E10 e k1 t E20 e k2 t 1 (Fig. 1). The emission rate started at the maximum value of 879 mg/m2 h and decreased to 33% of the maximum where within 15 min and to 0.15% within 24 h. The TVOC concentration resulting from the emulsion ± E(t) emission rate of TVOCs (mg/m2 h) polish increased to a maximum value within 3 h and re± E1 phase 1 (evaporation-dominated) emission rate duced to 9.8% within 24 h (Fig. 2). The maximum TVOC (mg/m2 h) concentration was 4.52 mg/m3. The emission rate started ± E2 phase 2 (diffusion-dominated) emission rate 2 at the maximum value of 292 mg/m2 h and decreased to (mg/m h) 2 45 mg/m2 h within 24 h. ± E10 phase 1 initial emission rate (mg/m h) )1 The measured TVOC concentration produced from the ± k1 phase 1 emission rate decay constant (h ) solvent furniture polish increased rapidly to a maximum ± E20 phase 2 initial emission rate (mg/m2 h) value 584 lg/m3 within 1 h and reduced to 35% of the ± k2 phase 2 emission rate decay constant (h)1). maximum within 8 h. It continued to decrease slowly from The mass balance for the chamber over a small time 8 to 24 h (Fig. 3). The emission rate started at a maximum increment dt is: of 4119 mg/m2 h and decreased rapidly to 0.3% of the Change in mass = Mass emitted ± Mass leaving maximum within 1 h and to 0.05% within 24 h. Figures 1±3 indicated that the TVOC concentration in chamber the chamber increased to a maximum within 3 h and then This can be expressed as: decreased rapidly to an undetectable or a steady equilibVdc AEt dt Qc dt 2 rium value within 24 h. The emission rate of aerosol spray and solvent polishes started at the maximum and dewhere creases rapidly to less than 1% within a few hours, while ± V chamber volume (m3) for the emulsion polish the emission rate started at the ± A sample area (m2) maximum value and declined slowly within 24 h. The ± Q ¯ow rate through chamber (m3/h) range of the maximum emission rate for the three furni± c chamber concentration (mg/m3) ture polishes was from 292 to 4119 mg/m2 h. Chamber studies are widely used to establish emission Integrating the chamber mass balance equation (Eq. 2) rates for VOCs from materials such as furniture polishes. with the source term de®ned by Eq. (1) and assuming an In order to obtain clear and speci®c results, which are initial concentration of zero gives the equation: not disturbed by other emissions, the use of inert supports such as glass or metal plates may be appropriate. c LE10 e k1 t e Nt =N k1 LE20 e k2 t e Nt = However, when the measured emission rates are used to N k2 3 estimate or model concentrations in a real indoor

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Table 2. Model derived emission parameters for furniture polishes Product

Squared correlation coef®cient (R2)

E10 (mg/m2 h)

k1 (h)1)

E20 (mg/m2 h)

k2 (h)1)

Sum of squared error (SSE)

Aerosol spray polish Solvent polish Emulsion polish

0.903 0.924 0.932

625 4104 80.7

10.2 3.23a 122b 438b

254 17.77 15.1 4.23 212 24.2

0.22 0.013 0.082 0.047 0.067 0.019

2.10 0.016 1.64

a b

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The uncertainty in the coef®cient The uncertainty in the coef®cient could not be estimated

environment, the possibility that emission characteristics may be changed by less inert supports has always to be considered. Therefore, further experiments in a variety of practical situations are needed to evaluate the possibility of extrapolating the results of this study to real situations. A high degree of reproducibility was found between duplicate TVOC concentrations recorded for the three furniture polishes. The reproducibility, expressed as the difference between duplicates divided by the mean, ranged from 6.5% to 10.4% for total chromatographed organics. In addition, recovery of the toluene ranged from 98% to 101% with a mean value of 100% (standard deviation 5%). Modelling The model-derived emission parameters for the furniture polishes are reported in Table 2. The quality of the leastsquares ®t can be assessed using the sum of squared error between observed and predicted values (SSE) and the squared correlation coef®cient (R2) as a measure of the degree to which the model ®ts the measured concentration±time pro®les. The uncertainties in the ®t coef®cients were estimated (Table 2). The coef®cient uncertainties were estimated from the variance±covariance matrix and the values displayed are the square roots of the diagonal elements. The variance±covariance matrix was calculated from the Jacobian matrix (MacCurveFit 1995). The uncertainty in the coef®cient for E10 was unable to be estimated. The squared correlation coef®cients (R2) ranged from 0.903 to 0.932, and the sum of squared error (SSE) ranged from 0.016 to 2.10 for the three furniture polishes. This indicated that the measured TVOC concentrations ®t the double-exponential model (Eq. 3) very well. The high value of k1 (compared with the value of k2, Table 2) suggested that the organic emissions from the furniture polishes decayed extremely quickly. The whole emission process was completed so quickly that most of the emittable organics were vapourised in the early period. This indicated that these furniture polishes were highemission but short-term decaying emitters of TVOCs. After the chamber had been loaded by the initial pulse of the organic emissions, the emission rates from the furniture polishes decayed to a negligible level and the organic concentrations in the chamber were diluted by the physical air exchange. According to the model (Eq. 3), E10/k1 and E20/k2 represented the total quantities of organic species emitted in phase 1 and phase 2, respectively (Wilkes et al. 1996; Chang et al. 1997). The values of these two parameters estimated from the chamber data are listed in Table 3.

Table 3. Estimated total quantities of TVOCs emitted from furniture polishes Product

E10/k1 (mg/m2)

E20/k2 (mg/m2)

Solvent polish Aerosol polish Emulsion polish

33.8 61 0.18

183 1170 3140

The amount of TVOCs released from the three furniture polishes ranged from 217 to 3140 mg/m2. The weight of TVOCs released per square metre of the emulsion polish was ®fteen times the weight emitted from the solvent polish. The total quantities of TVOCs emitted in phase 2 exceeded those in phase 1 (Table 3). This ®nding is consistent with those reported by Wilkes et al. (1996) and Chang et al. (1997). It is likely that the majority of the polish VOCs stayed in the wax of the polish sample. Only a small fraction of the polish VOCs stayed wet on the surface of the polish, resulting in the relatively short phase 1 emissions (Chang et al. 1997). The amount of TVOCs released from emulsion polish was higher than that released from other polishes (Table 3). This may be explained by the fact that the emission rate of TVOCs from emulsion polish decreased much more slowly than that from other furniture polishes. Although the solvent furniture polish had the highest initial emission rate of 4120 mg/m2 h, it decreased rapidly to only 0.3% of the maximum within 15 min and to 0.05% within 24 h. Similarly, for the aerosol spray furniture polish, the emission rate started at 879 mg/m2 h but it decreased rapidly to only 50 mg/m2 h within 7 h and to only 1.4 mg/m2 h within 24 h. For the emulsion polish, however, the emission rate was still 45 mg/m2 h after 24 h application, which was 15% of the maximum emission rate. Therefore, the emulsion polish emitted a higher amount of TVOCs than others. This also implied that when the TVOC emissions from different materials were compared, both the emission rates of TVOCs and the emission mass during the whole emission decay period should be considered. Most chamber experiments are designed to provide data that may be used in the estimation of population exposures. In theory, the double-exponential model presented in this study can be used to study material emissions in buildings, because the air and VOC transport can be described by the same equation whether in a small-scale chamber or in a real building. However, the problem is how to address the combined effect of various factors, such as air temperature, air velocity, relative humidity, and


material loading, on material emissions, because the ¯ow and thermal conditions may be complex in buildings. The concentrations of TVOCs measured in chambers in this study may overestimate indoor TVOC concentrations or personal exposure due to the use of furniture polishes, because as a proportion of the indoor air in buildings, the area covered by polishes in the chamber is far greater than the area that would normally be covered in a real house. This may account for the high concentrations of VOCs measured in these chambers compared with the levels in real houses. In this study, the maximum TVOC concentrations resulting from emissions from furniture polishes in the chamber ranged from 0.57 to 4.52 mg/m3, while a review of TVOC measurements (Brown et al. 1994) found that mean TVOC concentrations in established residences were 1.13 mg/m3 and in new buildings were approximately 4 mg/m3. Moreover, the TVOC concentrations in residences in Australia ranged from 32 to 143 lg/m3 and from 90 to 550 lg/m3 in of®ces (Brown 1997). Also, the chamber experiments indicated that the whole emission process from furniture polishes was completed quickly and most of the emittable organics were vapourised in the early period. Therefore, if these polishes were applied in a house only 1 day before the monitoring period, the TVOC emissions from furniture polishes would have been small. The experimental data obtained in this study, however, can be used to estimate indoor TVOC concentrations.

ing from emissions of emulsion polish was almost four orders of magnitude higher than that of solvent polish. Figures 4±6 showed that aerosol spray polish and emulsion polish emitted many VOCs, but solvent polish emitted relatively few. Inspection of the GC/MS data from the samples allowed their classi®cation into three groups: 1. Solvent furniture polish showed two large unidenti®ed peaks at 4.9 and 5.6 min. Both of these peaks had the same mass spectrum, which showed a single mass at m/z 57. The best spectral match was methylisocyanate. 2. All polish samples showed an aliphatic hydrocarbon peak at 7.5 min. In addition, these samples all showed a peak at 25.3 min, which was most likely to be limonene/ camphene. 3. The aromatic hydrocarbon pro®les of all samples were similar to peaks due to toluene, benzene, ethylbenzene, m-, p-, and o-xylene, and styrene.

Behaviour of model The degassing of a polish can be simply described by a model in which the total test system was divided into two compartments: source and gas phase (Fig. 7). Within this model a given VOC in the polish was diffused to the source/air interface with a rate constant k2 and then evaporated from the source/air interface to the gas phase with a rate k1. The gas-phase emissions, k1, correChemical characteristics of VOC emissions sponded to the period shortly after the polish was applied, The TVOC concentrations resulting from emissions from while it was still relatively wet. During this phase, the VOC furniture polishes based on static headspace analysis are emissions were evaporation dominated, and were characshown in Table 4. terised by relatively rapid emissions. These emissions Headspace analysis indicated that the concentrations of caused a rapidly depletion of organic compounds at the TVOCs for the three polishes were between 41.25 and surface of the polish, resulting in a rapid rise and decline of 10,600 mg/m3 (Table 4). The TVOC concentration result- the chamber concentrations. The emission rate k1 for this ``fast'' decline would be related to the vapour pressure of the speci®c VOC (Wilkes et al. 1996). The source-phase Table 4. TVOC concentration of furniture polishes (static head- emissions, k2, corresponded to the period when the polish space analysis) applied was relatively dry. During this period, the VOC emissions were dominated by diffusion through the source, Product Sample TVOC Number resulting in the emission rate k2 being low, but the emisconcentration weight of GC sions persisting for a long time. The rate k2 for this ``slow'' (mg/m3) (g) peaks decline would be related to the molecular weight of the Aerosol spray polish 0.7591 3010 30 speci®c VOC (Wilkes et al. 1996). The above hypothesis Solvent polish 4.8370 41.25 4 was re¯ected by the small values of k2 (compared with the Emulsion polish 1.6632 10,600 20 corresponding k1 value) as shown in Table 2.

Fig. 4. Gas chromatogram of aerosol spray furniture polish in static headspace analysis

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Proceedings of the 5th International Conference on Indoor Air Quality and Climate, Toronto, Canada, vol 3. The International Society of Indoor Air Quality and Climate, Ottawa, pp 731±736 Brown SK (1997) Indoor air quality, Australia: State of the Environmental Technical Paper Series (Atmosphere). Department of the Environment, Sport and Territories, Canberra Brown SK, Sim MR, Abramson MJ, Gray CN (1994) Concentrations of volatile organic compounds in indoor air: a review. Indoor Air 4: 123±134 Chang JCS, Tichenor BA, Guo Z, Krebs KA (1997) Substrate effects on VOC emissions from a latex paint. Indoor Air 7: 241±247 Colombo A, De Bortoli M, Knoppel H, Schauenburg H, Vissers H Fig. 5. Gas chromatogram of solvent furniture polish in static (1990) Determination of volatile organic compounds emitted headspace analysis from household products in small test chambers and comparison with headspace analysis. In: Walkinshaw D (ed) Indoor Air `90, Proceedings of the 5th International Conference on Indoor Air Quality and Climate, Toronto, Canada, vol 2. The International Society of Indoor Air Quality and Climate, Ottawa, pp 599±604 COST (1991). Guideline for the characterization of volatile organic compounds emitted from indoor materials and projects using small test chambers. COST Project 613, Report No. 8. Commission of the European Communities, EUR13593EN, Luxembourg Englund F, Harderup LE (1996) Indoor air VOC levels during the ®rst year of a new three-story building with wooden frame. In: Yoshizawa S, Kimura K, Ikeda K, Tanabe S, Iwata T (eds) Indoor Air `96, Proceedings of the 7th International Conference on Indoor Air Quality and Climate, Nagoya, Japan, vol 3. The Fig. 6. Gas chromatogram of emulsion furniture polish in static International Society of Indoor Air Quality and Climate, headspace analysis Ottawa, pp 47±52 HWRIC (1984) Chemical hazards in the home. Illinois Hazardous Waste Research and Information Center, Champaign, Ill., TN88±008a MacCurve Fit (1995) version 1.1. Kevin Ranger Software, Mt. Waverley, Australia Mùlhave L, Dueholm S, Jensen LK (1995) Assessment of exposures and health risks related to formaldehyde emissions from furniture: a case study. Indoor Air 5: 104±119 Niu JL, Lee LY, Lane-Smith D, Burnett J (1996) Non-speciated TVOC and speciated VOC measurements. In: Yoshizawa S, Kimura K, Ikeda K, Tanabe S, Iwata T (eds) Indoor Air `96, Fig. 7. The compartment mode Proceedings of the 7th International Conference on Indoor Air Quality and Climate, Nagoya, Japan, vol 3. The International Society of Indoor Air Quality and Climate, Ottawa, pp 357±360 Conclusions NSEC (1991) Household hazardous waste ± general overview. Environmental chamber tests showed differences in rates North Shore Ecology Center, Winnetka, Ill. Sack T, Steele D (1991) Indoor air pollutants from household and patterns of TVOC emissions from three furniture product sources. Project report for the Of®ce of Toxic Subpolishes. The change with time of TVOC concentrations stances. US EPA, Washington D.C., Publication # EPA 600/4± and emission rates in the test chamber from three 91/025 furniture polishes showed a good ®t with results from a Serber GA, Wild CJ (1989) Non-linear regression. Wiley Series in double-exponential model. The double-exponential model Probability and Mathematical Series. J. Wiley and Sons, provided reliable estimates of the initial emission rate, Auckland, New Zealand, pp 409±412 maximum TVOC concentration, mass of TVOCs released, Tichenor BA (1987) Organic emission measurements via small chamber testing. In: Serfeit B, Edsorn H, Fischer M, Ruden H., and other emission parameters. Data analysis indicated Wegner J (eds), Indoor Air `87, Proceedings of the Fourth that the double-exponential model can represent a twoInternational Conference on Indoor Air Quality and Climate. phase emission process. The hypothesis that emissions of Institute of Water, Soil and Air Hygiene, West Berlin, Vol. 1. TVOCs were evaporation controlled and then diffusion Institute of Water, Soil and Air Hygiene, West Berlin, pp 8±15 controlled was supported by experimental data. Wilkes C, Koontz M, Ryan M, Cinalli C (1996) Estimation of emission pro®les for interior latex paints. In: Yoshizawa S, References Kimura K, Ikeda K, Tanabe S, Iwata T (eds) Indoor Air `96, Anguenot F, Aigueperse J, Person A, Laurent AM, Virelizier H Proceedings of the 7th International Conference on Indoor Air (1990) Indoor exposure assessment resulting from use of Quality and Climate, Nagoya, Japan, vol 3. The International household products. In: Walkinshaw D (ed) Indoor Air `90, Society of Indoor Air Quality and Climate, Ottawa, pp 55±60