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IT] "CO~TIONS The Committee on Indoor Pollutants recognizes that decisions affecting the quality of the indoor environment are being made by manufacturers, government agencies, builder-, building operators, professional organizations, and private individual.. The decisions encompass a broad range of activities in our society, with important and long-term consequences. Federal agencies are planning energy-conservation programs in buildings, contemplating the banning of some products, and esti~ting the health risk associated with indoor pollutant exposures. State and local government units are considering revisions of building codes, ordinances to prohibit smoking in public buildings, and requirements that asbestos insulation be removed from schools. It can be presumed that there are similar examples of decision-making at various levels in the private sector that affect indoor environmental quality. In view of the possible impact of these decisions, the Committee is concerned that policy, research, and economic decisions be formulated with proper understanding of their implications for the quality of the indoor environment. For specific indoor contaminants, two basic inadequacies in the available data must be resolved rapidly: poor definition of population exposures and lack of understanding of the health and welfare consequences of exposure to contaminants in the indoor environment. This chapter presents the Committee'. general and specif to recommendations for remedying these inadequacies . We have observed that the existing cats base is, for the most part, derived from pilot studies or anecdotal reports. The results of the pilot studies reveal the complexity and diversity of the information that must be looked at in evaluating the quality of indoor environments. In some cares, the potential health significance of exposure to indoor contaminants has been alluded to; but the full extent of a potential problem with respect to types of contaminants, concentrations, and numbers of people exposed has not been determined. We believe that the research problem is large and requires national coordination. A national coordinated research program would have the following advantages: 46
~7 · It would provide reasonable allocation of research efforts among various federal agencies, national laboratories, and academic institutions. · It would provide standards for study design and quality assurance that are sufficient for various decision-making purposes. · It would provide integration of research activities and dissemination of the information derived. · It would provide maximal effectivenss of available funding. ! The objectives of such a research program should be these: · To determine the various sources and distribution of selected pollutants, to measure their ranges of concentrations, and to identify populations at r isk . · To understand how the contaminants move inside buildings, how they nix and react, and the rate at which they are repoured or dissipated under various conditions. · To characterize indoor pollutant emission source strengths under actual conditions. · To develop and test the effectiveness of control technologies. · To determine the effects of energy-conservation measures on indoor sir quality. To meet some of these objectives, there must be research aimed at developing improved instruments and at strategies for using them in the study of indoor pollutants. Instruments used to characterize indoor air quality reflect the early stages of this scientific endeavor. The sampling devices used in indoor studies were originally designed for sampling outdoor or industrial air. Many commercially available ambient-air monitors are bulky, noisy, and expensive and have not been tested for interferences that may be encountered indoors. These devices have mostly been judged to be inadequate for investigating indoor air quality, because their sensitivity, accura Q , and precision are not sufficient for the measurement of pollutants in the small volumes of air in indoor spaces. The Committee recognizes the importance of recent developments in the field of personal monitors; but it also recongizes the need for a simultaneous effort devoted to the development of air sampling devices designed specifically for indoor environments. The new instruments must be designed to record ~hort-term peaks in concentrations. Instrumentation alone is not sufficient for characterizing the indoor environment. Numerous variables indoors (perhaps more than outdoors) must be considered: some sources of pollutants are peculiar to some indoor environments; there are differences in structure type, ventilation, and other characteristics that affect pollutant concentration-; and activity patterns and time budgets of occupants vary. Human activity patterns and time budgets, which are essential in determining total exposures to air pollutants, are now derived from population surveys. These survey" do not require (and therefore do not obtain} information relevant specifically to indoor air quality. The Committee sees the need for analysis of these variables and their
~8 effects and reco_nds the development of ~1 strategies lfor sampling, etc.) or protocols as guidance for future research. (=e formulation of model sampling 8tr.~te8, for exile, is not want to stifle innovation in sapling designs, but rather to establish the model to be used for poppa ring data obtained by researchers whose objectives differ.) The Committee reca~ende the formulation of strategies and protocols for measuring the strength of Serious indoor pollu~nt-emitting sources and for 888e88inq the effectiveness of control devices and procedures in abating pollution. The Committee recommends the formulation of a standard foldout for reporting data and the develoF~nt of protocols for standardized statistical approaches that will require only clinic analysis to be used in validating numerical models. These wa,ld help to reduce difficulties in comparing existing data and facilitate the development of valid conclusions' conclusions now are often based on exceedingly s~11 Apples. , _, Even comprehensive information about the quality of the indoor environment would not permit determination of tote1 pollutant exposure. It must be recognized that people are exposed to many of the Awe pollutants outdoors, in transit, in the occupational- industrial environment, and elsewhere. The relative i~itance of each kind of enviroDent can be established and priorities can be set- if and only if pollution ensures in all distinct environments are characterized. I - Ok of a complete assessment guy lead to inefficient allocation of scientific effort and control funds in each kind of environment. me Committee believes that Me research efforts to characterize indoor air pollution and human exposures indoors aunt continue and intensify, if we are to determine total human exposure to pollutants and understand environmental contamination and its effects on health and the quality of life. The remainder of this chapter presents specific recommendations for research, grouped by class of indoor contaminant discussed in the body of the report, and discusses the need for increased understanding of indoor pollutants in general and the need for consumer protection. RADON ,- Nstionally coordinated investigations on radon ~nd its progeny should take place on two levels. A well-funded and coordinated national survey of radon concentrations in ~ representative apple of residential buildings ts necessary to activate the exposure of the total population to radon and radon progeny. Mbnitore that use the track-etch plastic chip may be adequate for integrated measurements for such national surveys, because they are inexpensive and are specific to radon. Bowever, the performance of these and other passive devices needs to be carefully evaluated. Inexpensive instruments for measuring radon concentrations on a short-tare basis need to be developed. mese instruments should be available to local health agencies and others for spot surveys. On another level, research on the transport and transformation of radon inside buildings
49 deserves special attention. Rates of emanation of radon from various sources, building materiale, soil, and qroundwater should be evaluated in a variety of on-site and controlled conditions. the effectivences of strategies for abating or eliminating indoor radon ~ including the use of material sealants and fine~aerosol collection devices) must be evaluated. There is an urgent need to study the health effects of radon and radon progeny. On the basis of known effects in miners exposed to radon and radon progeny at relatively high cor~centrations, a plausible case can be made that ~ substantial fraction of the lung~ncer incidence in nonsmokers is due to the alpha-rad$ation dose to the respiratory tract epithel$um from inhaled and deposited radon progeny particles. It is urgent that this obeer~rat$on be examined quantitatively by studies of appropriate human populations already know to be exposed at below 100 WHIM and preferably in the range of 20-50 WLM. It is known that in Bone geographic area. large populations are being exposed to radon gas and radon progeny particles in their residences at concentrations that, although much lower than those in uranium mines, are substantially higher than those in most residences. Epidemiologic studies of populations exposed to radon and radon progeny are reasonable and can provide the information necessary for the establishment of realistic and needed ex~sure-response relationships. These research studies should include examinations to determine early pathologic change. other than tumors (e.g., changes in sputum cytology and chromosomes aberrations), with 8"ci81 attention to the possibility of a relationship of those changes to the eventual development of lung cancer. Such studies should be performed as soon as possible. FOR M ALD1 3 " DE Simple and reliable passive monitors that would easily satisfy the requirements of large surveys of bu$1dinge for formaldehyde emission do not exist. Monitoring formaldehyde is extremely difficult, because of the influence. of temperature, humidity, and some analytic problems that affect its detection. Both continuous and passive monitors are needed with sensitivities in the range of 10-30 parts per billion. A national survey for indoor formaldehyde exposures is not needed. but systematic study of formaldehyde concentrations In a variety of indoor locations is needed to estimate potential exposure of humans. "is study would also identify sources of indoor formaldehyde by type of building and decorative materials and would evaluate the effects of ventilation rates and other variables on Me ooncentratior~. Regular measurements over specified periods would help to identify formaldehyde emission rates of insulating building materials and furnishings as functions of temperature, humidity, ventilation rate, and material age. Formaldehyde emitted from buildings and conquer products has resul~ced in complaints of adverse health effects by people in some mobile homes and in some conventional residences and other buildings.
so Some of thee emission occurs oared long periods. Thus, long-tere effects in Duane continuously exposed to for~aaldebyde at low concentrations need to be studied. There is a particular need to aseese the carcinogenic potential in the concentration ranges of human exposures, inasmuch as one study in one strain each of rats and mice hes shown that long-term exposure (~eating 24 ao) caused nasal cancer. Humans have been and are now being exposed to formaldehyde in several types of Pupations and in a variety of structures. Epidemiologic investigations are needed to assess the human health effects of formaldehyde, the magnitude and duration of exposure, and the influence of cigarette-~aoking habits and the presence of other contaminants. The mutagenic, ~bryotoxic, and teratogenic effects must be included in the epideaio10gic and animal studies. In humans exposed to formaldehyde, the aechani - s of airway and target cell responses must be evaluated and characterized as to sensitization and adverse effects in susceptible population groups, such as asthmatics and persons with chronic obstructive lung disease. Bxposure-effect relations and the mechanism involved in the biologic effects require further animal toxico10gic research. For~aldebyde abould be restricted to the extent that Ixweehold conquer products and building products in normal use will not release potentially hazardous or irritating Punts of formaldehyde into indoor air. TOBACCO SMOKE . Tobacco smoke has abown so~ evidence of being a major cont~nt in many indoor environments. Involuntary exposure to tobacco ~..~; should be assessed to identify locations and populations with been exposure and to determine the factors that contribute to high exposures indoors. physical and biologic evaluation of tobacco~eaoke constituents abould be continued. Tobacco-~moke constituents should be test" for their toxic effects, their ability deco act as mutagens or pr~otere of carcinogenesis, and their effects in combination with other indoor pollutants. In addition, such properties of tobacco Make as suse and age, chemical composition, irritation factors, and odor cooponente should be examined to learn how they are affected by ventilation rate, occupancy, extent of wok ing, air~cleaning . and other control strategies. The extent to which pismire exposure to sidestre~ tobacco Pike produces respiratory tract symptoms and functional decrements in non~okere, especially children, needs further documentation and measurement. prospective studies of children in hales with Here would be especially desirable to determine rates of lung Maturation and illness frequency during childhood and adolescence. Inforeation on the potential health effects of exposure of nonsmokers to tobacco Poke should be widely.disseminated. He ~energy~cost penalty. of providing adequate ventilation in indoor environments that permit Eking should be analyzed in a variety of public buildings. Increased cigarette taxation as a a'ec~ni" of
51 reimbursement for the cost of the additional air-conditioning needed to remove tobacco smoke should be explored by governments at all levels. ASBESTOS AND ASBESTIFORM FIBERS . . A systematic survey is needed for the evaluation of the distribution, integrity, and concentrations of asbestos in buildings that contain or are thought to contain asbestos material. Bowever, before this survey can be conducted, there is a need to develop new instruments to record fiber counts continuously, with ~ ice determination and possibly asbestiform-fiber identification, because current sampling and analytic.techniques are inadequate. Synergistic and interactive toxic effects of asbestos fibers in combination with other air pollutants, particularly organic vapors, should be examined in animal toxicologic and mutagenicity studies. Although come asbestiform fibers tbemselves do not appear to constitute an immediate health concern, their role as initiators or promoters in various disease processes should be studied. The incidence of mesothelioma in humans should be monitored via a registry and appropriate surveillance methods, to detect cases associated with substantial nonindustrial exposure to asbestiform fibers. Guidelines should be developed for the control of exposure to airborne asbestos fibers during maintenance, renovation, and reconstruction in buildings that contain asbestos and asbestos-bearing shingles, tiles, planter, etc. COMBUSTION Indoor combustion produces a number of contaminants. Among the contaminants that deserve special attention are nitrogen dioxide, carbon monoxide, respirable particles, nitrosamines, and ~ ~ aromatic hydrocarbon-. indoor combustion have not been adequately evaluated. The Committee recommends that controlled chamber experiments be conducted to determine the products and their rates of emission from various types of combustion under various conditions. These experiments should focus principally on gas and electric cooking appliances and supplemental heating systems, such as natural-gas, propane, and kerosene heaters and coal- and wood-burning stoves. Air-venting and air-cleaning systems should be studied as means of reducing indoor concentrations of contaminants. Indoor concentrations of combustion products have only recently been surveyed. Combustion products are present in many indoor polynuclear The rates of their emission from sources of powered equipment. locations, such as restaurants, cafeterias, homes, hotels, buildings with attached garages, and recreational facilities that use gasoline- More comprehensive and systematic surveys are needed to identify the range of c~mhustion-product concentrations encountered indoors and the numbers of people exposed to them. These .
52 studies should determine the population exposure to nitrogen dioxide over both the short and the long term. In addition, the applicability of a~hient-air fixed-location monitors for recording nitrogen dioxide and carbon monoxide concentrations indoors and for assessing individual exposures should be studied. Chemical reactions and rates of renal of emitted gases should be determined. Nitrogen dioxide formation and removal should be examined in detail. This will in~rol~re the simultaneous measureacnt of other gaseous compounds. me effects of reduced air-exchange rates, zone ventilation, and source Edification on pollutant reactions should be assessed. As with other indoor contaminants, there is a general need to improve instrumentation. Both nitrogen dioxide and carbon monoxide monitors are available for passive integrating sapling and for continuous monitoring. Bowever, for indoor use, they need to be evaluated with respect to interferences. To evaluate short-term personal exposures, lightweight continuous monitors for oxides of nitrogen need to be developed. Evaluation of personal exposures to re~pirable particles is currently limited to integrated samples. Lightweight portable samplers or direct-reading monitors that can measure mass concentration over shorter periods are needed. Nitrosamines can be for~d during cooking and Poking. forever, very few detailed investigatione of the concentrations, aeebanisas of formation, and potential control methods have been done. The polynuclear aromatic hydrocarbons can be forced during high-temperature combustion of organic Batter. Some of them have been found indoors as a result of emission from self-cleaninq ovens and fireplaces. Pilot studies should be initiated to evaluate the extent of emission of polynuclear aromatic hydrocarbons and their indoor concentrations . The magnitude and prevalence of decreases in pulmonary function and increases in respiratory tract infection rates among children living in homes with gas ranges and homes with electric ranges need to be determined more accurately, and there are several related issues that require clarifications · Whether the effects are due entirely to the increased nitrogen dioxide concentration in the gas-stove homes or are influenced by the presence of other combustion effluents from the Stoves, such as carbon monoxide, formaldehyde, and particles. · Whether the effects can be related Sore closely to peak concentrations or to long-term average exposures. · Whether the effects of exposures to sideatream cigarette spoke and to nitrogen dioxide are additive or synergistic. · Whether exposure-response relationships can be developed and, if so, whether they indicate an effective threshold concentration for peak or average exposures. The influence of reductions in air infiltration rates in existing buildings on indoor Concentrations of combustion products needs to be determined. Among the potentially serious health consequences of reductions in infiltration are:
53 . Creation of greater pressure differentials between the indoors and the outdoors, which could reduce the effectiveness of the venting of combustion sources, e.g., furnaces and water-heatere. Problems in proper venting could cause substantial exposures to carbon monoxide (which could lead to severe intoxication and fatalities), as well as greater exposures to carbon dioxide, ni~crogen dioxide, formaldehyde, and particles. · Increase in chronic exposure. to carbon monoxide, nitrogen dioxide, formaldehyde, and particles at low concentrations frae unvented combustion sources; this could lead to increases in respiratory infections in children and decreases in their lung function . CONSUMER PRODUCTS The use of some consumer products can lead to the release of aerosols and gases indoors. The gaseous compounds of concern are mostly organic vapors. Among the compounds of principal concern are aldehydes and polynuclear aromatic hydrocarbons that evolve from plasticizers; nitrosamines and hydrocines from rubber products, combustion products, and cleaning agents' polychlorinated biphenyle (PCBe) from burnt-out ballasts in fluorescent lighter and a variety of other middle- and higher-molecular~weight organic subetances from pesticides. A few studies have noted the presence of many of these compounds indoors. However, no systematic survey has been done. With regard to the evolution of organic Molecules from pesticides, organochlorinated pesticides should be examined first, including aldrin, dieldrin, endrin, benzene hexachloride, pentachlorophenol, depone, chlordane, and DOT. The emphasis should be on the determination of body burdens of these compounds and specifically the relative contributions of inhalation, ingestion, and absorption to body burdens e The contents of consumer products should be investigated, and the chemical constituents should be tested for their toxic, mutagenic, carcinogenic, and teratogenic properties. In particular, there should be toxicologic studies of solvents, vapors, aerosols, and particulate compounds present in these products. Their synergistic and interactive effects with other indoor pollutants should be tested. Consumer products whose use involves the release of gaseous and particulate materials to the indoor atmosphere should be so labeled, with their components. Warning labels for consumer products that can seriously pollute the indoors should state that they are to be used only in area- with adequate ventilation and should stipulate the possible consequences of their use when there is inadequate ventilation.
54 A~PA=OG=S AND IS Little is known about the sources, concentrations, and survival rates of many seropathogens in hods and other buildings. Relationships among the incidence of respiratory infections, concentrations of aeropathogens. and air~exchange rates in buildings must be examined. The urgency arises from the recent modifications in building ventilation codes that recommend reduced ventilation rates I residential and commercial structures. A sample of co~ercinI, institutional, and residential build_nge should be evaluated for the types and concentrations of aeropathogens under ~ variety of conditions of occupancy, human activity, ventilation, humidity, temperature, and contaminant control. Special attention should be given to the newer energy-efficient buildings and buildings with drastically reduced ventilation. me potential for infectious contamination from air-cleaning filters, air heat-exchangers, air humidifying systems, and air-conditioning systems deserves special attention. Other agents in the indoor environment known to produce allergic responses include pollens, household mites, molds, animal dander and excrete, and bacterial spores. Further work is needed to characterize the size distribution of allergen aerosols, their sources, and the conditions that are conducive to their generation. The airborne concentration of allergens in the indoor environment has been determined in only a few instances, and the relationship between indoor concentration and response is poorly understc~d. Case~control epidemiologic and immunologic studies are needed to clarify exposure-effect relationships. Such studies will require improved instrumental and analytic techniques to facilitate characterization of concentrations of allergens and of the variety of microorganisms in the indoor environment. Synergic of biO\ - iC and nonbiol~ic agents should be explored in animal toxicology studies. Some acute allergic responses, such as ~h~idifier fever,. are of unknown etiology. me pathologic agents in immunologic and cese- control epidemiologic studice need to be identified. The pathogenic process by which repeated small exposures to soot allergens often lead to irreversible fibrotic lesions, as in bird-fancter's disease, should be elucidated, and the potential of other, acre ca~n inner pollutants to produce such disease states should be evaluated. VENTILATION STANDARDS AND COST - L STRA1~GIBS , . . Knowledge of ventilation rates is of priory importance in studies of indoor contaminant concentrations. Given the variety of residential living units and other public and private facilities, it i. not surprising that very little information exists to characterize air-exchange rate.. Studies should begin to characterize air-exchange rates in existing buildings by building type, geographic location, occupant life styles, building operation, and observed average pollutant concentrations during the different seasons. Smaller-ecale
55 studies over a considerable period are recommended to characterize sir exchange and its effects on occupant babavior in a representative number of buildings. This information would help to show the relationships among air-exchange rates, pollutant concentrations, pollutant generation, occupant behavior, and physiologic effects, an well as the effects of energy-con~ervation programs aimed at reducing air inf titration rates. With the objective of maintaining indoor air quality, while not adversely affecting heating and cooling cost., there is a need for engineering studies to determine alternative strategies for air dilution of pollutants. Case studies of specific buildings may be useful in determining the efficiency of selected filtration- ventilation Schemes. For example. it may be economically preferable to filter (or scrub) recirculated air or a mixture of recirculated and makeup air to maintain indoor air quality. Studies should be done on the effectiveness and energy-conservation implications of pollutant sensors used to activate air-dilution or air-cleaning system. Engineering studies on both air handling and air treatment systems are encouraged. Although specific buildings may be studied in detail, the application of the findings should be generic; i.e., the lessons learned should be applicable to other buildings. Standard methods should be developed and applied to evaluate the performance of in-place environmental control systems and components. Improved methods of providing acceptable and eff icient air diffusion for thermal and contaminant control should be developed. Life~cycle cost evaluations should be made on the basis of current and projected energy costs to characterize these costs for future use in alternative designs of residences and large buildings. Air-conditioning, heating, and ventilation systems especially should be evaluated, in connection with other building characteristics. EXPOSURE STtlDIES Proper assessment of indoor contamination needs a perspective that only total-exposure studier can provide. The relative contributions to individual and population exposures of the contaminants encountered indoors, with both indoor and outdoor sources, must be evaluated. For contaminants with multiple entry. routes, the contribution of inhalation of indoor.ppllutants must be compared with all other contributions to body Ardent. Only with this evidence can research and control efforts be prudently allocated. Under current conditions, studies of total exposure to many contaminants are limited by the available instrumentation and, to a lesser extent, by analytic methods. Such efforts are expensive. The extrapolation of their results is constrained by the smallness and often the unrepresentativeness of the samples of participants, by the inadequacy of the information on activity patterns in the population at large, and by lack of understanding of the distribution of indoor and outdoor pollutant sources and the pathways that contribute to body burdens. However, studies of total exposure and an understanding of At,
56 activity-related concentration date will eventually advance our knowledge of pollutant exposure. This knowledge is a prerequisite to rational allocation of resources for warranted reductions in population exposures. The Committee urges investigation in the behe~riora1 aspects of indoor environments, apecif $cally the relationships one performance, sense of well-being. contaminant concentrations, and stress. Temperatures, odors, and noise outside preferred ranges can reduce productivity, especially in self-pacing tasks . The relationship between productivity and the quality of the indoor environment needs to be determined. It is recognized that rela~cionships between the behavioral variables and pollutant concentrations soy be difficult to establish. Simultaneous aeas~:ements of trace organic vapors, water-vapor content, conductivity, noise, light, temperature, and sir exchange rates should be pursued. EDUCATION Public education offers an effective way of reducing exposure of the population to many contaminants encountered indoors. People informed about the potential for exposure to pollutants from Consumer products, tobacco spoke, combustion products, etc., w$11 exercise sooe Control to reduce the pollutant concentrations in their environments. For the most part, their option. for controlling these pollutants are limited to source maintenance, ventilation control, and, to some extent, air~cleaning. Information about mainlining a clean indoor en~rironacnt and assessing indoor spaces for potential contamination before purchasing or renting ~ structure and ~ variety of suggestions could be disseminated through health-~intenance organizations, regional health-planning agencies, public~affaire off ices, the Environmen"1 Protection Agency, the Department of Housing and Urban Development, the Depar men t of Energy, the Consumer Product Safety Commission, and a variety of other federal and state agencies. Me General Services Administration, the armed forces, and the Department of Bousing and Urban Development are responsible for many residences and other buildings. Through certification of m$nt~1 acceptable occupancy standards, these federal-organizations could develop strategies to ensure Ant indoor spaces under their Jurisdiction are free from hazardous concentratione of oontaminants. Professional and trade associations could be instrumented in developinq and disseminating information. These associstione are encouraged to catabliSh standards for acceptable practice, with respect to manufacturing, designing, building, and using products, equipment, and structures that influence the quality of the indoor air.
