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Atmt+ktnc tamw Vl II, N#. J. pp. JlS-Hfi. I*7, hwiil in Gnu tnui*. wscyVivume cH_ott'bE -- CPSC. CONSIDERATIONS IN EVALUATING EMISSIONS FROM CONSUMER PRODUCTS John R. Girman and Alfred T. Hodgson Building Ventilation and Indoor Air Quality Program, Lawrence Berkeley Laboratory, University of California, Berkeley. CA 94720, U.SA and Marilyn L. Wind Division of Health Effects, U.S. Consumer Product Safety Commission, Bcthesda. MD 20207, U.SA (First received 22 July 1985, in finalform 17 February 1986 and received for publication 30 July 1986) Abstract--While several indoor air quality studies suggest consumer products (e.g. aerosol sprays, paint removers, etc.) can be significant sources of volatile organic compounds, until recently characterizing! emissions from consumer products has rectived relatively little attention. Many considerations that must be addressed in designing studies ofconsumer product emissions are similar to those addressed in studies of the emissions from building materials and combustion appliances. These similarities are discussed and. in addition, the considerations unique to studies ofconsumer product emissions are discussed with reference to an ongoing study of consumer products that contain methylene chloride. These unique considerations include bulk chemical analysis, the form ofthe product (e.g. liquid, aerosol or paste)and the related consumer usage pattern. The issue ofpersonal exposure of the product user vs the average area concentration resulting from product use must be considered, as well as the challenge of incorporating results into predictive models that adequately treat the effect of different usage patterns. Finally, post-study considerations, such as exploring new issues discovered in the study, studying similar products, and validating predictive models through extension into field studies are summarized. Key word index: Consumer product, emissions, indoor air quality, methylene chloride, personal exposure, source characterization, ventilation. 81381 INTRODUCTION While several indoor air quality studies suggest that consumer products can be significant sources of vol atile organic compounds (De Bortoli et al,, 1985; Lebret et al., 1984), characterization of emissions from consumer products has received relatively little atten tion. This is in strong contrast to the characterization of emissions from combustion appliances (Johnson et aL, 1984; Leaderer. 1982; Traynor et aL, 1982) and building materials (Girman et al, 1987; Molhave, 1982), where numerous chamber studies have been conducted. In this paper, considerations necessary for evaluating emissions from consumer products in lab oratory studies are presented. Although a broad definition of consumer products could include many combustion appliances and some building materials, a narrower definition as used in the National Academy of Sciences monograph. Indoor Pollutants (National Research Council 1981) is em ployed in this paper. As used here, it is limited to expendable products in small containers which are readily available in retail outlets. In this context, consumer products are items such as cleaning/potishing products, insecticides, painting/finishing/refinisbJng products, personal grooming products, hobbyists' products, and deodorizers/disinfectants. Many considerations that must be addressed when designing studies of emissions from consumer prod ucts are similar to those addressed in other types of indoor air quality studies. These similarities include; defining the potential health hazard; establishing study goals; assessing analytical instrument and chamber capabilities; pretesting and establishing the experimen tal procedures; and establishing quality assurance/con trol objectives. There are, however, additional con siderations that are unique to studies of consumer product emissions. These unique considerations in protocol develop ment are discussed with reference to an ongoing study ofconsumer products that contain methylene chloride (CHiCl;). This study, supported by the U.S. Consumer Product Safety Commission (CPSCX was undertaken by Lawrence Berkeley Laboratory (LBL) to resolve uncertainties about the exposure consumers can receive by using consumer products containing CHjCl,. LBL has conducted a controlled study in an environmental chamber to measure both the airborne concentrations produced by the use of these products and the exposures of individuals using them. Development and testing of models for both average ana concentreu n and personal exposure are import ant goals of this study. In discussing considerations for studies ofconsumer ' 315 316 John R. Girman tt u/. products, eight major tasks are defined. While the ACQUIRING APPLICATION TECHNIQUE AND USAGE order ofpresentation ofthe tasks is reasonable, it is not a rigid prescription. Certain tasks should be ac complished before starting the next task: however many tasks can be accomplished in parallel or, as is often required, in an iterative fashion. * PATTERN INFORMATION In completing this task, the goal is to acquire sufficient information about product application and use to assure that the product is used realistically in test situations. The term "application technique" is used to denote the detailed method employed by the consumer DEFINING THE POTENTIAL HEALTH HAZARD when using the product. e.g. for a paint remover. "Use a single brush stroke, applying in one direction only. Many interrelated factors must be considered in defining the potential health hazard of a particular product orclass ofproducts: the chemical composition of the product; the toxicity of the compounds con tained in the product: an estimate of airborne concen trations and exposures produced by the use of the product; the market penetration (either at the present time or expected in the future due to changing market conditions); and an estimate of the population poten tially at risk. This task should not be confused with actually developing an estimate of a health risk due to use of a product. This would be premature since too many parameters are not sufficiently well known. Rather, the goal at this sage is to judge whether the potential risk is large enough to warrant a detailed study. This initial task is similar for most indoor air pollutant source characterization studies. In some respects, this task is more easily completed for con sumer products than for other indoor air pollutant sources such as combustion appliances, building ma terials or smoking, since consumer products generally have labels describing their chemical content. However, these labels, while useful as a guide, are not necessarily comprehensive and chemical analyses are usually required. A good example of defining a potential health hazard is provided by CHjG2, a chemical widely used by consumers. More than half of a billion pounds of CHjClj are produced annually in the U.S., much of it for use in paint removers and aerosol finishes (Anonymous, 1985). The chemical composition of these products is readily obtained. For example, semi paste paint removers contain approximately 85% CHjClj and aerosol with CH2G2 generally contain 20-40% of this chemical. Market data also exist for these products, although these data are not Wait at least 10 min before scraping." Since consumer products are found in a number of different forms including aerosols, liquids, semi-pastes or gels, pastes or waxes, and solids, a broad range of application techniques must be anticipated. In contrast to this, usage pattern information is broader in scope. It would, ideally, include such data as amount used in various applications, frequency of use. typical room volumes and air exchange rates where the products are used, the frequency with which con sumers increase ventilation by opening windows and/or doors, and the size and types ofobjects to which the products are applied. 1 There are several ways to acquire information about application techniques and usage patterns. Manufac turing trade associations for the product type may share their market research data about techniques for application and how consumers actually use the product. User surveys are another, probably better, method of acquiring information. These range from structured surveys with questionnaires to informally questioning colleagues and acquaintances about their personal use of specific products. However, one of the best and most readily available sources of information is probably manufacturers' information sheets and the instructions printed on product containers since these are the source of information most often used by consumers. For the methylene chloridestudy two major product types with very different forms were investigated: paint removers, which are primarily semi-pastes, and aerosol finishes. Information about application techniques and product usage was acquired through informal surveys (including personal experience on the part of the researchers and program managers) and manu facturers' information sheets and instructions on pro duct containers. discussed here. There is concern about consumer exposure to CH2C12 from these products, since CH2G2 retained in inhalation is metabolized to carbon monoxide, which ESTABLISHING STUDY GOALS can lead to anoxic stress from elevated levels of This task allows the greatest latitude and, accord carboxyhemoglobin (Ratney at aL 1974; Stewart <r aL ingly, the greatest creativity for researchers and pro 1972). In addition, a recent animal-inhalation labora gram TM"prL since a wide range of choices is tory study has associated increased "V'-h-v- of car available to shape the direction and goals of the study. cinoma with exposure to CH2G2 (Peer Review Panel. Initially, it must be decided if the study should be National Toxicology Program Board of Scientific biased toward a "worst case' use or toward a more Councilors, 1985). These facts strongly suggest that typical product use or both. A wont case scenario may there is a potential health risk that is worth be appropriate when acute health effects are ofinterest investigation. and are likely to occur within the population with some SL 040058 free pn a: li tr.i te* irr peari' par z1 ing bot. exp are: tra: are sire the of . com son: O tech proc this Fs limit restr whic time In focu It w with ant: wou the attet toiui cone this] attet used 3.0 corr actic indo (A c obje cea* cone cases kitch be p! pain two< rem< V ACE and next alto tmer *Usc inly. tmer inns sites uion n is u as `use, ethe conlows hich bout jfacmay s for the :tter, 'rora nally iuon ithe bese 1 by duct mint osol ques anal rt of anupro* irdpro s is sdy. 1 be sore may jest jme Consideration* in evaluating emissions from consumer products 317 frequency. A typical use scenari may be more appro priate f r chronic health effects or to estimate the typical exposure of larger populations. Very often, source characterization is a primary goal and this characterization can be done with respect to time (in which case the form of the product and the method of application are important): with respect to temperature (where the form of the product may be important); with respect to the ventilation rate (or perhaps with respect to local air flows near the product and user); and/or with respect to other environmental parameters. Another decision must be made regarding measur ing area concentrations vs personal concentrations or both. The person using the product can receive an exposure far different than would be predicted from an area sample taken in the same room. The concen tration gradients in rooms where consumer products are being used may be large and. therefore, may have a strong effect on personal exposures. This may lessen the importance of area concentrations in the absence of a model correlating personal exposure to area concentrations and increase the importance of per sonal sampling. Of course, as discussed previously, the application technique can affect emissions from a consumer product. Therefore, it must be decided if the effect of this source of variability is to be measured. Finally, the goals must be prioritized. Because of limited resources, the scope ofa study must usually be restricted in some way. The actual decisions as to which goals will be pursued need not be made at this time, but they should be prioritized. In the methylene choride study, for example, the focus of the study was to be typical use, not worst case. It was further decided that source characterization with respect to time and ventilation was most import ant and that the effects of temperature and humidity would be studied later, if at alL While characterizing the emission of CH202 would receive the most attention, the emission of other major solvents such as toluene would also be monitored. The average area concentration and personal exposure were judged, at this point, to be equally important and the study would attempt to measure both. The ventilation rates to be used were both low, OJ air changes pa- hour, and high, 3.0 air changes per hour. These ventilation rates may correspond to the situation when a consumer takes no action to increase ventilation while using the product indoors and the situation when windows are opened. (A consumer could also, in some simatrons, take the object to be painted or stripped outside. However it ceases to be an indoor air quality problem under these conditions and, more importantly, is not an option in cues when the object is a permanent fixture, ef, a floor, kitchen cabinets or wall panels.) While the panels to be paint stripped in this study were to be primed and painted several months before the experiments with two coats ofenamel paint, which tends to be difficult to remove, they were to be modest in size (compared to wall panels, kitchen cabinets or a floor) and they were to be relatively smooth (compared to lathe-turned legs or a carved piece of furniture) and therefore easily stripped. Overall the choices made tended to cor respond more to typical not worst case, use of the product ASSESSING INSTRUMENTAL AND FACILITY capabilities Based upon the prioritized list of goals, the re searchers must assess the resources available to con duct the study, in terms of both instruments and a chamber or other specialized facility. This is a straightforward task. For the methylene chloride study, a continuous i.r. analyzer was to be used to monitor both the personal and area concentrations on an alternate basis by means of sample line switching. Sampling with charcoal tubes was originally considered for personal sampling, but was rejected for this phase of the study because of insufficient precision and time resolution. A gas chro matograph (GC) was also available. A chamber de signed for studies of organic emissions was available. Its ventilation system was adequate in terms ofair flow and size, but at the time, it lacked temperature and humidity control However, since stria requirements were not established for these parameters, control could be accomplished simply by controlling the temperature and humidity of the laboratory housing the chamber. Data acquisition systems and a host computer were available for logging ofanalog and digital input signals from the Lr. analyzer, the GC and the environmental instrumentation, but some software had to be written. WRITING the protocol In writing the protocol all of the information collected regarding product types, application tech niques. usage patterns, study goals and the analytical instrument and facility specifications are considered and brought together to construct a unified plan. The detailed experimental procedure is written, incorporat ing the specific instruments and the chamber capabi lities. Calibration procedures are established in detail Consideration should also be given to data acceptance standards. However, in research, as opposed to moni toring. it is inappropriate to set rigid standards for all types of data. Standards can be set for the limits of acceptable data for envirotnental parameters, for in strumental drift and for the precision of calibration data. However, setting standards for other data can be difficult due to lack of knowledge about the behavior ofthe source and the effect ofactivity on the part ofthe person using the produce Audit procedures should be set and written as part of the protocol The audit can take two forms: internal where checks of instruments, procedures and data are SL 4005g 318 John R. Gisman *t aL conducted and recorded by the researchers themselves trial experiments also provide data for testing data according to a formal plan: and external where an reduction and analysts schemes. Often it is discovered outside agency or individuals check the instruments, that the protocol and checklist should be modified procedures and data. based upon the knowledge and experience gained in A detailed checklist ofspecific actions to be executed the pretest period. before, during and after an experiment should be In the example study, the bulk chemical analysis of constructed from the key elements of the protocol. paint removers confirmed a high percentage of Writing the checklist at this time serves to insure that CHiCli and lesser amounts of toluene and aliphatic the protocol is practical and reasonable. However, the alcohols. The bulk analysis of selected aerosol paints checklist should not be viewed as a static endpoint but, and other aerosol finishes showed lesser percentages of rather, as the first draft of a document that will evolve CHiGj but larger amounts of toluene and. in some as the researchers gain experience. cases, minor amounts of other solvents. In the current example, the protocol for the meth A sampling system was fabricated that switched ylene chloride study was written by the LBL staff and alternately between a personal sample taken near the sent to the CPSC for review. The protocol specified the breathing zone of the person using the product and an instruments and the calibration procedures to be used. average area sample consisting of the sum of 13 It established internal audit procedures and named a sampling locations in the chamber. These 13 locations quality control officer. It described the sampling are located throughout the chamber at three different system, the ventilation rates, the environmental par heights. ameters. the substrate to be finished or stripped and The \s. analyzer was calibrated for CHjCL using incorporated manufacturers' instructions for product both the manufacturer's closed-loop injection system use. Incorporating the instructions for the use of paint and a mass-flow controlled dynamic gas dilution removers, in particular, required careful consideration. system with certified gas standard mixtures. Agree Paint remover was to be applied sequentially to small ment between techniques was excellent, but the sections (0.37 m1) of a 1.5-nr panel. Paint remover dynamic technique was chosen for use in the exper would set for a minimum of 10 min prior to scraping. iments because of ease and speed of use. Tools, remover containers and paint scrapings would Application techniques for paint removers were all be weighted so that the weight data could be used as standardized. Preliminary experiments demonstrated a check of the emission rates developed through the that CH.Gi emissions could be well characterized and use of a mass-balance, ventilation model CPSC chose that even short-term variations could probably be to obtain outside review of the protocol. Comments characterized. However, personal exposure concen and suggestions from CPSC and the outside reviewers trations appeared to be highly variable and could not were incorporated into the protocol by LBL. be tracked adequately when sampling was alternated between personal and average area locations. PRETESTING Therefore, it was decided to obtain a second i.r. analyzer so that both personal and average area The pretest period is one of the most interesting concentrations could be measured continuously. The periods of a study because the learning curve is so protocol was modified to reflect this change. steep. The products are selected for screening and The preliminary experiments also graphically de subjected to bulk chemical analysis, generally by GC monstrated that the products must be used realistically and/or GC/mass spectrometry. Based upon the results to obtain valid emission rates. If paint remover was of the bulk analysis and market considerations, the applied to a panel and allowed to set undisturbed, the specific products to be studied are selected. The remover didn't appear to evaporate appreciably and performance of the analytical instruments is evaluated emissions were relatively low. However, if the paint using the calibration procedures. During this period, remover was agitated by scraping, the remover would more than one calibration system may be used as an evaporate to near dryness within 5-10 min and emis overall check of one system against the other. sions were large. Similarly, vertical stratification of Sampling systems are fabricated, if necessary, and/or concentrations was also more evident if paint remover tested. Data acquisition software is debugged, and the was undisturbed. acquisition system is tested. If at all possible, trial experiments should be con ducted and concentrations measured. During these trial experiments, the product application technique is CONDUCTING THE STUDY evaluated and standardized. This is especially import Once the necessary preparations have been made, ant if more than one person will be applying the completing this task is relatively straightforward and. product during the experiments and measurement of again, is similar to most indoor air pollutant source the efleet in variability ofapplication technique is not a characterization studies. If at ail possible, the first study goal The overall experimental procedures are expenmenu should be replicate experiments to quan evaluated, as well as the adequacy f the sampling tify the reproducibility of the experimental procedure. system and the analytical instruments employed. These For these experiments, the same person should use the SL 040060 product ar cate events of variatic sufficient, termine wr detect char The retrL replicate ex. reduced. Th experiments ventilation tr. appliance stu. temporal var: products, it r model than c al,, 19851. Tht to adequately The data fr calculate pers pared to expo centrations. Sr conducted to . parameters, e.g. ventilation rate exposure derivei The cham be chloride study Hodgson. 1985 product types vs the cates were cc used (as determii of product appll the average c breathing-zone c by the use of a pa in the 20-mJ cl concentration fluuse of the paint rt Fig. 1. Temporal pr concentrations of C paint remover in a 2 3-23 h`l. Duracion o At end of work pent switched to latx lodified lined in lysis of age of Uphatic I paints ages of n some vitched ear the and an of 15 nations iflerem i using system ilution Agreeit the exper- i were trated d not sated lions, d i.r. area The / decaily was i, the and saint ould misa of over Consideration* in evaluating emission* from consumer products 319 product and every attempt should be nude to dupli cate events even ifa later goal is to determine the effect of variations in application technique. If the data are sufficient, statistical tests can be employed to de termine whether the reproducubility is adequate to detect changes due to experimental variables. The remaining experiments are conducted after the replicate experiments are completed and the dau are reduced. The average concentrations obtained in the experiments are incorporated into a mass-balance ventilation model such as has been used in combustion appliance studies (Traynor of,, 1982). Because of the temporal variation of emissions from some consumer products, it may be necessary to use a version of this model than can address these variations (Traynor aU 1985). The model may require some modifications to adequately treat a unique data set The dau from personal sampling can be used to calculate personal exposures and these can be com pared to exposures estimated from average area con centrations. Statistical analyses of the dau can be conducted to assess results with respect to selected parameters, e.g, by product type, by product brand, by ventilation rate or by exposure (personal exposure vs exposure derived from the average area concentration). The chamber experiments for the methylene chloride study have been completed (Cirman and Hodgson. 1985). The emission rates for the two product types varied, of course, but the differences in the rates were consistent with the amount of CH2C1Z. used (as determined by bulk analysis) and the duration of product application and use. Temporal profiles of the average chamber concentrations and the breathing-zone concentrations of CHjGj produced by the use of a paint remover at a high ventilation rate in the 20-mJ chamber are shown in Fig. 1. The concentration fluctuations produced by the sequential use of the paint remover are clearly evident. Temporal profiles of CHjG] concentrations were calculated from source strengths, the ventilation rates and the chamber volume using single-equation, mass-balance models. For paint removers, two types of source strengths are used: (he first, the time-averaged source strength,assumed that the product was used uniformly over time for the duration of the entire work period; the second, the time-dependent source strength, ac counted for the sequential nature of product appli cation. As illustrated in Fig. 2 which contains the modeled profiles from the same experiment illustrated in Fig. 1. these theoretical concentrations were m good agreement with measured concentrations. Exposure models based upon the concentration models were also developed and then evaluated by comparing theor etical and measured exposures for the experiments. When measured personal exposures were compared to chamber concentrations ofCH-G2 integrated over the work periods, agreement was good at the low venti lation rate but averaged 21 % higher at the high ventilation rate. For the experiment illustrated in Figs 1 and 2, the exposures were 1120 ppm-h (personal exposure), 921 ppm-h (exposure based upon average chamber concentrations) and 1180 ppm*h (theoretical exposure). For the same paint remover used in an experiment at the low ventilation rate, the exposures were 2400 ppm-h, 2350 ppm-h and 2530 ppm-h, re spectively. The exposure models appeared to have sufficient accuracy and precision for use in assessment of health risk from the use of consumer products containing CHZG2. POST-STUDY CONSIDERATIONS Iffunding is available, the research may be extended to explore issues ignored because of limited resources; to explore new issues discovered in the study; to study sic; nd. Fig. 1. Temporal profiles of chamber and breetiung-zooc Fig. 2. Temporal profiles of theoretical dumber concen tee concentrations of CHzOj during an experiment with a tration* of CHjOi for an experiment with a peim irtt paint remover in a 20-mJ chamber at a ventilation rat* of remover in s 20-u"J chamber at a ventilation rate of 3.23 h*'. Duration of work period is shown above curves. 3.23 h"'. Concentration* were calculated wing both At end of work period, breathing-zone sampling line was time-depended and tune-averaged source strength*. switched to laboratory air external to chamber. Dunoon of work pxnod is shown above curves. SL 040061 320 John It Gihun it of. similar products; or petWps most importantly, to validate the model developed by conducting a field study. For the methylene chloride study, the remaining issue is the validation of the exposure models de veloped in a field study which will examine the efiects of variations in ventilation patterns and rates, in volumes and in product use patterns. Office j>( Building Energy Research and Development. Buddings Systems Dmnoo ofthe US Department of Energy under Contract No. DE-ACD3-76SF00098 and by the Directorate of Health Srwncrt ofthe Ui, Consumer Product Safety Commission underContract No. CPSC-1AG-84-I 171. The ideas and opinions expressed are those ofthe authors and not necessarily those ofthe U.S. Department of Energy or the U.S. Consumer Product Satiety Commission. Thu material is in the public domain and in accordance with 17USC 103 may be fully copied or reprinted. PERSONAL PROTECTION Personal protection for the researchers deserves special mention. Unlike studies of combustion appli ances and building materials where it is not necessary for researchers to have prolonged exposure? to emis- using consumer products can often result in extended pertccs of -xpoaj:-. "esearehers should be protected even if some accuracy is sacnticed. In the methylene chloride study, a pressure-demand breathing appiratus supplied by a cylinder of air v _thech. : - ws 'yth-;----- -a L-'i-g ,l r product durin.c the experiments. Because the mask '.da'' ..- , 'treoi... f ;fe wear--:, it .may h-i -'..o the fv tn.ii same .. No.netr- esi. perscr,.. p.utcct.cn l' precedence fV.r'-'sa'-ir ov--ilis. we-e -*v..i Curing t.-.0 : .e-.'.ly the per ' - ri-e t1-- prouuct to prevent certr.ai contact. V'uo.t rio'-es we:, also worn during the use of paint removers. U ,.J, vl tiki . d' Sumer products ..j.-u bee.. - . .oss-d '' ,t t.fere___to eight tasks that should be accomplished when conduc ting such a study; (1) defining the potential health hazard; (2) acquiring application technique and usage pattern information; (3) establishing study goals; (4) assessing instrumental and facility capabilities; (5) writing protocol; (6) pretesting; (7) conducting the study; and (8) post-study consderarioa*. These con siderations are discussed using examples provided by an ongoing study of methylene chloride emissions from paint removers and aerosol A""1"- Emphasis is given to those considerations thatare unique to studies of consumer products. These considerations indude the need to use the products realistically to obtain valid data, the difference between personal exposure and exposure based upon the average concentration and the factors that affect this difference, and the need for personal protection of the researchers. Acknowledgment*--This work vws supported by the Assistant Secretary for Conservation and Renewable Energy. REFERENCES Anonymous (19831 Resource Center. Pollut. Etu/nf 17,48-31. De Bortoli M,, Knocppd H. Pecchio E- Pei! A. Rogora L. Schaucnburg H. Schlitt H. and Vissers H. U985) Measurements of indoor air quality and companion with ambient air. Commission of the European Communities Joint Research Center Report EUR 9656. Otfice for Official Publications of the European Communities. Luxemoourg. Giiman i. R. and Hodgson A. T. 11983) Source characteriz ation and personal exposure to methylene chloride from consumer products. Lawrence Berkeley Laboratory R.por; LSLC.'ZZT. Laurence Berkeley Laooratory, Berkeley, CA, G-man J. R, Hod cson A. T,, Nedton A. S. and Winkes A. W. Il'J'-iri Emissions of volaiild Organic compounds from acnesives with indoor applications. Emir. Ini. tin pressl. Jor.nson D., Billick U Mosch-ndreas D. and Reluoam S, ri'-'j-t. Emission rates from u.ivenied gas appliance, Proc. 3ru /nr. Conf. on Indoor air Quality and Climair, Vol. 4, pp. 367-373, Swedish Council for Building Research. Stockholm. Sweden. LeaOs.'e: B. P. (I`'Ll Air pollutant emissions from kerosene space heaters. 5 :rn.-f 3IS. 1113-1115. Leo;.. ... van ue wiei h. J.. .os H. P, Non 0. and 3oi.ij J. S. 1198-t) v -natile hydrevarbons in dutm homes. Pros*. . ..Cony.. ~' and C`. utr. Voi. 4. - iaj-i34, Sue.tish Cou~: 1 ror Build ng Researcn. Stockholm, Sweden. Mothave L (1982) Indoor air pollutant* due to organic pie* and vapor* of totems in building material*. Emir. hu. 8. 117-127. National Research Council. Nauonal Academy of Science* (1981) indoor Pollutants. Nauonal Academy Pres*. Washington. DC. Peer Review Pand (1983) Nauonal Toxicology Program Board of Scientific Coundlon, 29 March 1983. Research Triangle Park. NC Ramey R. S, Wegman D. H. and Elkin* H. B. (1984) In moo conversion of methylene chloride to carbon monoxide. Arch. Eiwir. HUM. 28, 223-226. Stewart R. D,, Fisher T. N,, Hosko M. J, Peterson J. E- Baretta E. D. and Dodd H. C (1972) Experimental human exposure to methylene chloride. Arch. Emir. HUh 25, 342*348. Traynor G. W,, Anthoo D. W. and Hollowell C D. (1982) Technique for determining pollutant emission* from a gas- fired range. Aouotphrhr Emironmont 16, 2979-2988. Traynor G. W,,Gifnmn J. R~Aptc M.G-DiUwonh J. F.and White P. D. (1915) Indoor air pollution due to cmismon* from unvented gai-fired space beaten. J. Air PoIIul . Control An. 35,231-237. 0A0062 SL fafttol tft C co.isum environ: atrquali can pro' nation < source* that sir 1984. 1 1982a; I terizatit pound. sion* f; recent : of a b 1982b; by De have a source The method strong! for tht Ren tton Agi Martin