Commentary Environmental Health and Safety Concerns and Energy Conservation Practices in Academic Institutions and Hospitals ROGER L. DEROOS, MPH, PHD
Abstract: Although there are many energy conservation practices which are now being applied in hospitals and academic institutions, there will be additional pressures for even further reductions in such energy use in the near future. In many instances, these reductions in energy use can be done within existing standards and do not endanger the health of persons who reside within these institutions. However, this pa-
per highlights the fact that over-eager attempts at energy reduction may result in adverse effects on patients, students, staff, research programs, or the general public. For this reason, it is important for persons making decisions regarding energy conservation practices to be aware of these potential adverse effects and design energy conservation programs accordingly. (Am. J. Public Health 68:1011-1015, 1978.)
Introduction
general considerations, however, several specific institutional environmental health and safety concerns arise when one tries to reconcile energy conservation with: 1) ventilation for control of toxic or infectious agents, provision of comfort, prevention of heat stress, and fire control; 2) lighting for patient care or treatment, building sanitation, food preparation, safety, and security; and 3) hot water for sanitation of food, linen, equipment, and building space.
With the current increase in attention being given to energy conservation measures, those who are administrators or involved with environmental health and safety programs in academic institutions or hospitals have another concern to add to already crowded lists of priorities. Attempts must be made not only to conserve energy, for that is certainly in the long-term interest of our nation, but attention must also be given to preventing adverse health effects of energy conservation measures. This article seeks to alert readers to energy-wasting features that have been built into hospital and research laboratories and to draw attention to the potential for compromising health of patients or the safety of employees if energy conservation practices are applied too eagerly. The focus of this article will be on two critical areas of the institutional environment: the hospital and the research laboratory. Perhaps, the most obvious, and most publicized, energy-related problems have involved the lack of emergency fuel supplies and the possibility that changes in fuel supplies, such as a change from natural gas to coal, could result in general degradation of our environment. In addition to these Address reprint requests to Roger L. DeRoos, MPH, PhD, Associate Professor and Director, Department of Environmental Health and Safety, University of Minnesota, Minneapolis, MN 55455. This paper, submitted to the Journal December 12, 1977, was revised and accepted for publication May 16, 1978.
AJPH October, 1978, Vol. 68, No. 10
Background Regarding Hospitals In 1975, there were 36,157,000 admissions to the 146,000 hospital beds in the 7,156 hospitals across the country.I This does not include nursing homes and other long-term health care facilities, which are also consuming a significant portion of our nation's energy 24 hours a day, 7 days a week. It has been estimated that hospitals consume approximately 15 per cent of all energy used in commercial structures throughout the country (the equivalent of 400,000 barrels of oil a day). Approximately 30 to 50 per cent of this energy is used for heating and another 10 to 15 per cent for cooling. Certainly, attention to heating, ventilation, and air conditioning systems is one factor of prime importance in conserving energy in hospitals and other health care facilities.2 There are many energy conservation measures that health care facilities can initiate without seriously compromising the health and safety of patients and staff. As early as 1974, the "American Hospital Association Guidelines on 1011
COMMENTARY
Energy Conservation in Health Care Institutions"* provided a variety of suggestions, such as turning off lights when not in use, checking efficiencies of the heating plant, insulating pipes to prevent heat and cold loss, and eliminating decorative lighting. Although these measures have few implications for health and safety, other suggestions were made that require some scrutiny before being put into practice, e.g., changes in hot water temperatures, and changes in heating, air conditioning, and ventilating levels. When considering ventilation, it is interesting to look at some early experiences. In the late 1700s, John Howard, an Englishman, noted the good ventilation in Guy's Hospital. He wrote, "Many are here cured of compound fractures, who would lose their limbs in the unventilated and offensive wards of some other hospitals."3 In her Notes on Hospitals, Florence Nightingale cited certain faults in hospital ward construction, stating that unhealthy conditions were due to "construction of hospitals on a plane that prevents free circulation of fresh air . .. ward construction not conducive to ventilation because of defective sites . . . defective natural ventilation in warming."4 From this early recognition of the need for control of ventilation, standards have evolved for the design and operation of heating, ventilation, and air conditioning systems. The most important consideration in establishing hospital ventilation standards was to promote the welfare of the patient. The other consideration was to avoid adding unnecessarily to the cost of construction. Conservation does not appear to have been a prime consid-
eration. Health care facilities are justifiably designated as priority users of natural gas, heating oil, and other fuel sources. Not only are hospitals virtually guaranteed an uninterrupted supply of fuel, there has been reluctance to lower any heating, air conditioning, or ventilation standards because of concerns about possible adverse effects to the health, safety, and comfort of patients. Furthermore, on such short notice, it has not been possible to initiate significant changes in the operation of heating, air conditioning, and ventilation systems. Hospital engineers are working with systems that were designed to give optimum protection to patients and staff, not to conserve energy. It has been said that, "There is a limit to how low we can set the thermostat for sick and elderly patients. Air conditioning is not a luxury in patient care and certainly not in the operating room. Ventilation made possible by powerdriven fans is tightly controlled by federal regulation. Few appreciate the fact that a hospital is divided into positive and negative pressure zones to reduce the possibility of crosscontamination. Humidity levels are controlled for optimum patient care and to avoid fire and shock hazards in critical areas."2 Very few, if any, hospitals in the United States have been designed with energy conservation as a prime concern; nor have operational and preventive maintenance programs *These guidelines, published in an AHA newsletter, will have been updated and should be available from AHA for those who wish to write. 1012
for these facilities been implemented with emphasis on energy conservation.
Ventilation Standards for a Complex Hospital Environment Many special air conditioning and ventilation standards relate to the complex hospital environment. In addition to controlling the movement and amount of air to be supplied to, or exhausted from, critical areas, even the conditions of normal air movement must be controlled. Furthermore, the overall quality of the air is important. Quality requirements include the usual ones of temperature and humidity but, in hospitals, both chemical constituents and biological contaminants are also of vital concern.3 This complexity is increased even further with new developments in health care: infants with low birth weight, patients in kidney dialysis, and patients with a depressed immune response due to the use of chemotherapy in the treatment of cancer. All are extremely susceptible to environmental insults. In some instances, this iasd to further refinement in the use of ventilation techniques fo ontrol of infection, for example, laminar airflow rooms. There are those who would suggest, however, that laminar airflow operating rooms have not been proven a successful technique for reducing infection rates.2 A hospital is not only complex because of the wide variety of medical services that may be provided, but also because of the variety of support services. In many areas, ventilation is used to control sources of humidity, air-borne cross-contamination between clean and dirty areas, odors, and excessive heat build-up. Examples include the handling of linen and solid waste, where there are both clean and dirty areas; food services, where odors, grease, humidity, and cross-contamination potential must all be considered; and central sterile supply areas, where excessive humidity, crosscontamination of the clean and dirty areas, and excessive heat build-up must be controlled. Traditionally, ventilation standards have been developed to control these conditions. Now, however, one other ingredient must be stressed: energy conservation. In each of these cases, it should be questioned how one can continue to accomplish the objective outlined above, yet prevent excessive energy use at the same time. Is it possible where air is being exhausted to control heat build-up, humidity, or odor, to condition the air so that it can be recirculated to other portions of the building (e.g., storage areas), and the heat content recovered? Can recirculation be practiced to a much greater extent (possibly even mandated) for hospital operating rooms? Comparison must be made of the ability of the various systems to meet the health and safety needs of the patient and personnel with a minimum of energy consumption. An example is cited from a recent study on the discharge of potentially toxic anesthetics from operating rooms.5 If these waste gases are discharged through the exhaust from the operating room, we are led back to the need for 100 per cent exhaust, similar to the time when flammable anesthetics were used. In this study, the authors not only consider the health effect of the waste anesthetic gases, but also, in a time AJPH October, 1978, Vol. 68, No. 10
COMMENTARY TABLE 1-Energy Consumption in Heating and Cooling Operating Room Air* (Energy Consumption, BTU's/Yeart)
Chicago Heating Cooling Houston Heating Cooling Los Angeles Heating
Cooling San Francisco Heating Cooling
Non-recirculating
Recirculating+
11.8 x 109 6.7 x 109
0.03 x 109 4.6 x 109
5.8 6.0
x 109 x 109
2.4 x 109 23.6 x 109
0.0+ 12.0 x 109
1.2 21.0
x 109 x 109
15.7
0.0± x 109
0.97 x 109 7.4 x 109
0.0+ 6.9 x 109
0.38 x 109 7.3 x 109
7.1
0.0 x 109
2.6 x 109 2.37 x 109
0.02.32 x 109
1.0 x 109 2.354 x 109
0.0 2.347 x 109
Heat Pipes
Thermal Wheels
0.59 x 109 5.2 x 109
tBased on air supplies at 550 F, 80 per cent RH, exhausted at 70° F, 50 per cent RH, with the room heating load assumed constant. Based on 24 hr/day usage, 65,000 cfm. +Assuming an optimum system that mixes supply and exhaust air in the appropriate ratio to minimize heating and cooling. The maximum recirculation was 80 per cent. ±The assumed constant heat load from the room was sufficient to heat incoming air. *Source: Piziali, et al. Ref. no. 5.
of sensitivity to energy consumption, compare various systems for conserving energy (Table 1). This study illustrates the types of comparisons that need to be made, and the need to consider public health concerns when comparing systems. The original reference5 should be consulted for further detail regarding interpretation of results.
Ventilation of Research Laboratories In turning attention from ventilation of hospitals to ventilation of research laboratories, we find similar consideration must be given to building and room air supply. Often, however, laboratory hoods gain the most attention when the topic of energy conservation and laboratory ventilation arises. This can be easily understood when one considers that the amount of heated air exhausted through a conventional laboratory fume hood is often in the vicinity of 1,000 to 1,500 cfm. Therefore, energy conservation proposals involving changes in laboratory hood operation are very tempting. This potential avenue for energy conservation must be approached very cautiously, however, so that we do not compromise what may be the most important safety device in a laboratory. Before one considers changes in operation of laboratory hoods, some thought needs to be given to the purpose of these hoods. Conventionally, we think of the fume hood as a device for exhausting toxic materials or flammable vapors during the course of an experiment. In most laboratories, however, these hoods may also be: a) used for temporary storage of a variety of chemicals, b) the source of exhaust for a flammable solvent storage cabinet located under or adjacent to the hood, or c) the means of disposing of small amounts of volatile solvents by evaporation. In addition, it must be remembered that research personnel do not follow a five-day a week, 8:00 a.m. to 5:00 p.m. work schedule, but AJPH October, 1978, Vol. 68, No. 10
often use laboratories during evenings and weekends. A temporary shut-down could decrease the efficiency of laboratory hoods, and could inadvertently expose laboratory personnel to chemical or fire hazards. The Department of Environmental Health and Safety staff at The University of Minnesota has concluded that changes in laboratory ventilation systems to conserve energy must be approached on a building-by-building basis. This method will require that someone become totally familiar with the design of the ventilation system and take measurements to determine operating characteristics of the system. Effective ventilation modification can then be individually tailored to meet specific system designs and operating characteristics. In existing buildings, a survey could be conducted to determine use of laboratory hoods; joint use might be arranged of some of the hoods that are underused, or some units could be shut down or sealed off. With sealing off an existing hood, however, evaluation must be made of potential adverse effects on ventilation balance in the laboratory or in the portion of the building in which the laboratory is located. Also, when buildings are connected via tunnels and corridors, interaction of ventilation systems and the changes in these interactions caused by changes in operation of ventilation systems in one or more of the buildings must be considered. Assuming that one proceeds cautiously, there are possibilities for energy conservation in laboratories. These include use of the heat in laboratory hood exhausts and recirculation of general room air. Another way to conserve energy from laboratory hoods is to include fewer hoods in the design of a new building. To accomplish this, consideration should be given to shared use of hoods by two or more laboratories. For example, a group of laboratories could be designed so the hoods, and possibly other shared facilities such as autoclaves and centrifuges, are near the hub of a group of
laboratories. 1013
COMMENTARY
The possible ventilation practices that could conserve energy involving laboratory hood ventilation include: use of heat exchange equipment; use of two-speed fans, and reduction of supply air. Heat exchange equipment in laboratories is the best system for both ensuring health and safety of personnel and conserving energy. It has the following advantages: * Keeping the hood velocities high at all times and eliminating any possible flammable or toxicological problems; * Conserving energy (heat) on a 24-hour basis; * Keeping a margin of safety for occupants by still providing 100 per cent make-up air; and * Being applicable to any exhaust air-general or fume hood exhaust. Two-speed fans can also be used to conserve energy. If this approach is used, face velocities of laboratory hoods when the facility is not being used must be at least 25 fpm to ensure that stored chemical agents present no flammable or toxicological hazard. For adequate removal of odors, vapors, and fumes from the general laboratory when the room is not in use, the room exhaust ventilation, provided by fume hoods, should not drop below 6 air changes per hour. A system to ensure full face velocity when hoods are in use must be an integral part of the two-speed fan system. An example of such a system would be one in which normal "high" fan speed is resumed in the laboratory when lights were turned on. It must be emphasized again that any ventilation changes, such as the installation of two-speed fans, must be scrutinized on a building-by-building, system-by-system basis. Variables such as the design of the existing air system, general ventilation characteristics of the facility, and hours that the facility is used are factors to be weighed when considering a two-speed fan system. The additional costs of ensuring health and safety via monitoring must also be considered in the feasibility study of this approach. A third energy conservation measure would be to reduce the supply air to the facility and maintain hood operation 24 hours a day. Supply air cannot be reduced to the point where hood face velocities drop below 25 fpm when the facility is not in use. Such a ventilation system also would require a control system to ensure "normal" supply air to the facility when in use. The possibility of recirculation of laboratory air, although attractive for energy conservation, presents a variety of potential health and safety problems. In facilities with biological, chemical, or other air contaminants (dusts, fumes, etc.), a recirculation system may not be applicable. Recirculation eliminates the safety factor of 100 per cent outside clean air continually diluting contaminants that could be generated inside the facility. The use of recirculation of air would have to be approached with great caution. Therefore, a recirculatip system is almost always limited to such areas as offices, classrooms, and the very few laboratory facilities that are free from airborne contaminants. A thorough monitoring program must be implemented to test, initially and periodically, the filtration systems in any recirculation system that is installed. In addition, an accurate and up-to-date 1014
report on how the facilities are used is mandatory when such facilities are recirculating air. Maintenance programs should be of fail-safe quality.* Complete shut-down of ventilation systems may also have implications in regard to fire safety in hosptiallresearch complexes. Recognizing that (particularly in a multi-story building) it is impractical to evacuate the entire building, compartmentalization of the building and control of smoke in the building may depend upon design of the ventilation system. For example, consider a building that is divided into four zones for ventilation. The fire alarm system may be designed so that if smoke is detected in the ductwork in one of the areas, the air supply to that area automatically shuts down. Air exhaust fans continue to operate and create a negative pressure in the area where the fire is located. At the same time, the ventilation for other zones of the buildings may be altered to include an increase in the quantity of air or a decrease in the quantity of exhaust air. This is to prevent smoke and gases from moving into zones that are outside the fire area. If there are portions of the day when ventilation systems are shut down, this early detection and compartmentalization of the building by ventilation would be compromised. In a building that is totally vacated during evening hours (when ventilation systems are shut down), this may not be of great consequence. However, in a medical/research complex, that includes patient-care areas, shutdown of portions of the ventilation systems for all unoccupied areas of the complex may seriously hamper the total fire protection system for the complex.
Miscellaneous Illumination is another area in which we have environmental health and safety concerns. Some of the areas of concern are building sanitation, patient safety, and employee
safety. 1. Building Sanitation. There must be sufficient lighting throughout hospitals so that personnel in housekeeping, maintenance, food service, and other areas who have responsibilities for cleanliness of the institution can do their jobs adequately. This would even include illumination for the more remote areas of the building, such as storage facilities for food and medical supplies, where adequate lighting may be important for cleanliness and insect and rodent control. There are standards that specify lighting levels for a variety of areas in the institutional environment. For example, food service standards specify lighting levels for food preparation surfaces, equipment and utensil washing areas, floors, refrigeration and dry food storage, and toilet areas. The primary reason given is that "ample light, properly distributed, makes dirt conspicuous, is necessary for the proper preparation and handling of food, and is imperative for the complete cleaning and sanitization of equipment and utensils."6 2. Patient Safety. With older patients in particular, there may be already some loss of visual acuity. This human factor, added to a decrease in quality or quantity of lighting, *Personal Communication from K. Carlson, Department of Environmental Health and Safety, University of Minnesota. AJPH October, 1978, Vol. 68, No. 10
COMMENTARY
will undoubtedly contribute to patient injuries resulting from slips and falls. Particular attention must be given to elimination of glare, and the provision of adequate light in areas where patients will frequent: adjacent to the bed, between the bed and bathroom, in the bathroom, in hallways, etc. When one examines patient injury statistics, these areas are where most of the injuries occur. Of course, there are also indirect implications to patient safety in non-patient areas of the hospital, such as areas where medications are prepared and where electronic equipment is maintained. 3. Such factors as contrast, brightness, and the amount of glare can be of importance to the safety of employees.7 If lighting is poor, additional physical energy will be required to perform job tasks. This may result in tiredness and increased possibility of an accident. As is true for patients, falls, and slips, and similar accidents can occur if light is improperly directed on corridors and steps. For such areas as the shops, glare and shiny surfaces may increase the hazard in the use of moving machinery. Recognition of the standard safety colors is an important concern, and Jensen reports that recognition is satisfactory down to a level as low as five foot candles. He recommends that it may be necessary to reexamine the OSHA (Occupational Safety and Health Administration) standard that recommends one half foot candle for safety lighting in active areas.7 Jensen also indicates that, according to the National Safety Council, 5 per cent of all industrial accidents are caused by insufficient lighting, and in 20 per cent of these cases, illumination and eye fatigue contributed to the accident.7 Another concern in the shop area is the stroboscopic effect of high intensity lights. When a high intensity lamp such as a mercury vapor lamp is used, brief, intense bursts of light energy may at times be in synchrony with the movement of a piece of shop equipment, such as a table saw. Hazard results when this synchronized movement gives the impression that the saw blade is standing still. To prevent this from happening, fixtures can be connected on three-phase wiring with alternate fixtures on different phases. The reason this is mentioned in conjunction with energy conservation is that high-intensity lamps may be substituted because they require less energy. 4. Emergency and outdoor lighting are two other areas that have received attention in the search for steps to conserve energy in institutions. The purpose of emergency lighting is to ensure, first, that one can find where the emergency exit is located, and second, that all surfaces are sufficiently lighted to prevent tripping or falling over objects that might be in the path of egress. The NFPA (National Fire Protection Association) standards require that the minimum lighting level in the path of egress be one foot candle.8 Energy conservation minded individuals may complain that a building appears to be excessively illuminated when, in fact, the quantity of light is only that required for emergency lighting. It should be remembered that emergency lighting must provide enough light to meet the requirement of one foot candle at the fringes of the area illuminated. Parking areas and other outdoor areas are of particular AJPH October, 1978, Vol. 68, No. 10
concern for employees in hospitals because of around-theclock shift changes. Some institutions have gone to the use of high intensity sodium lighting for outdoor lamps to increase efficiency of lighting without lowering intensity. Adequate lighting needs to be provided for accident prevention and for adequate security. Although there are some minimum standards for parking garage areas, this area of concern can only be evaluated on an individual basis, depending upon local circumstances.
Water Temperature The temperature of hot water is of critical concern, particularly in the hospital environment. The water that comes in direct contact with patients must not be too hot, generally less than 1100 F. In other areas of the institution, however, water used for cleaning and sanitizing must be hot enough to enhance the cleaning process and help provide sanitization. Areas where hotter water is needed include dishwashing, linen reprocessing, patient equipment processing, laboratory glassware washing, and animal cage washing. Animal cage washing, for example, usually requires water temperatures of 1400 F and 1800 F for adequate washing and sanitizing. This is not to say that some steps cannot be taken to conserve energy in the hot water supply system. Such steps can include designing systems for recirculation, and insulating pipes. In some instances it may be possible to lower hot water temperature. For example, temperature of water for laboratories in the classroom building might be lowered from 1400 F to 1100 F. With a booster heater, a similar lowering of temperature could be achieved in the food service facility. Hot water can be conserved by replacing old shower heads with the newer design that operates at a lower flow rate. If it is economically feasible, there could possibly be some heat recovery from water discharge from laundry machines. The temperatures in washing and sanitation cycles in laundry, dishwashing and glass washing, and cage washing machines, however, should remain at their present levels.
REFERENCES 1. American Hospital Association. Guide to the Health Care Field. AHA, Chicago, 1976. 2. U.S. Department of Health, Education, and Welfare. Energy Strategies for Health Care Institutions. April 1976. 3. Bond RG, Michaelson GS and DeRoos RL, ed: Environmental Health and Safety in Health-Care Facilities. New York: Macmillan, 1973. 4. Nightingale F: 3rd Ed. Notes on Hospitals. Longman, Roberts, and Green. London, 1863. 5. Piziali R, etal: Distribution of waste anesthetic gases in the operating room air. Anesthesiology, 45(5), November 1976. 6. U.S. Public Health Service. Food Service Sanitation Manual Including a Model Food Service Sanitation Ordinance. Pre-Publication revision, U.S. Department of Health, Education, and Welfare, 1976. 7. Jensen JH: The Role of Light and Radiant Energy in Health and Safety. Professional Safety, 12-16, April 1977. 8. American National Standards Institute. Practice for Industrial Lighting. 1430 Broadway, NY, 1973.
ACKNOWLEDGMENT This study was supported in part by contract HW-7405-Eng. 48, from the Energy Research and Development Administration, Washington, DC. 1015
Abstract: Although there are many energy conservation practices which are now being applied in hospitals and academic institutions, there will be additional pressures for even further reductions in such energy use in the near future. In many instances, these reductions in energy use can be done within existing standards and do not endanger the health of persons who reside within these institutions. However, this pa-
per highlights the fact that over-eager attempts at energy reduction may result in adverse effects on patients, students, staff, research programs, or the general public. For this reason, it is important for persons making decisions regarding energy conservation practices to be aware of these potential adverse effects and design energy conservation programs accordingly. (Am. J. Public Health 68:1011-1015, 1978.)
Introduction
general considerations, however, several specific institutional environmental health and safety concerns arise when one tries to reconcile energy conservation with: 1) ventilation for control of toxic or infectious agents, provision of comfort, prevention of heat stress, and fire control; 2) lighting for patient care or treatment, building sanitation, food preparation, safety, and security; and 3) hot water for sanitation of food, linen, equipment, and building space.
With the current increase in attention being given to energy conservation measures, those who are administrators or involved with environmental health and safety programs in academic institutions or hospitals have another concern to add to already crowded lists of priorities. Attempts must be made not only to conserve energy, for that is certainly in the long-term interest of our nation, but attention must also be given to preventing adverse health effects of energy conservation measures. This article seeks to alert readers to energy-wasting features that have been built into hospital and research laboratories and to draw attention to the potential for compromising health of patients or the safety of employees if energy conservation practices are applied too eagerly. The focus of this article will be on two critical areas of the institutional environment: the hospital and the research laboratory. Perhaps, the most obvious, and most publicized, energy-related problems have involved the lack of emergency fuel supplies and the possibility that changes in fuel supplies, such as a change from natural gas to coal, could result in general degradation of our environment. In addition to these Address reprint requests to Roger L. DeRoos, MPH, PhD, Associate Professor and Director, Department of Environmental Health and Safety, University of Minnesota, Minneapolis, MN 55455. This paper, submitted to the Journal December 12, 1977, was revised and accepted for publication May 16, 1978.
AJPH October, 1978, Vol. 68, No. 10
Background Regarding Hospitals In 1975, there were 36,157,000 admissions to the 146,000 hospital beds in the 7,156 hospitals across the country.I This does not include nursing homes and other long-term health care facilities, which are also consuming a significant portion of our nation's energy 24 hours a day, 7 days a week. It has been estimated that hospitals consume approximately 15 per cent of all energy used in commercial structures throughout the country (the equivalent of 400,000 barrels of oil a day). Approximately 30 to 50 per cent of this energy is used for heating and another 10 to 15 per cent for cooling. Certainly, attention to heating, ventilation, and air conditioning systems is one factor of prime importance in conserving energy in hospitals and other health care facilities.2 There are many energy conservation measures that health care facilities can initiate without seriously compromising the health and safety of patients and staff. As early as 1974, the "American Hospital Association Guidelines on 1011
COMMENTARY
Energy Conservation in Health Care Institutions"* provided a variety of suggestions, such as turning off lights when not in use, checking efficiencies of the heating plant, insulating pipes to prevent heat and cold loss, and eliminating decorative lighting. Although these measures have few implications for health and safety, other suggestions were made that require some scrutiny before being put into practice, e.g., changes in hot water temperatures, and changes in heating, air conditioning, and ventilating levels. When considering ventilation, it is interesting to look at some early experiences. In the late 1700s, John Howard, an Englishman, noted the good ventilation in Guy's Hospital. He wrote, "Many are here cured of compound fractures, who would lose their limbs in the unventilated and offensive wards of some other hospitals."3 In her Notes on Hospitals, Florence Nightingale cited certain faults in hospital ward construction, stating that unhealthy conditions were due to "construction of hospitals on a plane that prevents free circulation of fresh air . .. ward construction not conducive to ventilation because of defective sites . . . defective natural ventilation in warming."4 From this early recognition of the need for control of ventilation, standards have evolved for the design and operation of heating, ventilation, and air conditioning systems. The most important consideration in establishing hospital ventilation standards was to promote the welfare of the patient. The other consideration was to avoid adding unnecessarily to the cost of construction. Conservation does not appear to have been a prime consid-
eration. Health care facilities are justifiably designated as priority users of natural gas, heating oil, and other fuel sources. Not only are hospitals virtually guaranteed an uninterrupted supply of fuel, there has been reluctance to lower any heating, air conditioning, or ventilation standards because of concerns about possible adverse effects to the health, safety, and comfort of patients. Furthermore, on such short notice, it has not been possible to initiate significant changes in the operation of heating, air conditioning, and ventilation systems. Hospital engineers are working with systems that were designed to give optimum protection to patients and staff, not to conserve energy. It has been said that, "There is a limit to how low we can set the thermostat for sick and elderly patients. Air conditioning is not a luxury in patient care and certainly not in the operating room. Ventilation made possible by powerdriven fans is tightly controlled by federal regulation. Few appreciate the fact that a hospital is divided into positive and negative pressure zones to reduce the possibility of crosscontamination. Humidity levels are controlled for optimum patient care and to avoid fire and shock hazards in critical areas."2 Very few, if any, hospitals in the United States have been designed with energy conservation as a prime concern; nor have operational and preventive maintenance programs *These guidelines, published in an AHA newsletter, will have been updated and should be available from AHA for those who wish to write. 1012
for these facilities been implemented with emphasis on energy conservation.
Ventilation Standards for a Complex Hospital Environment Many special air conditioning and ventilation standards relate to the complex hospital environment. In addition to controlling the movement and amount of air to be supplied to, or exhausted from, critical areas, even the conditions of normal air movement must be controlled. Furthermore, the overall quality of the air is important. Quality requirements include the usual ones of temperature and humidity but, in hospitals, both chemical constituents and biological contaminants are also of vital concern.3 This complexity is increased even further with new developments in health care: infants with low birth weight, patients in kidney dialysis, and patients with a depressed immune response due to the use of chemotherapy in the treatment of cancer. All are extremely susceptible to environmental insults. In some instances, this iasd to further refinement in the use of ventilation techniques fo ontrol of infection, for example, laminar airflow rooms. There are those who would suggest, however, that laminar airflow operating rooms have not been proven a successful technique for reducing infection rates.2 A hospital is not only complex because of the wide variety of medical services that may be provided, but also because of the variety of support services. In many areas, ventilation is used to control sources of humidity, air-borne cross-contamination between clean and dirty areas, odors, and excessive heat build-up. Examples include the handling of linen and solid waste, where there are both clean and dirty areas; food services, where odors, grease, humidity, and cross-contamination potential must all be considered; and central sterile supply areas, where excessive humidity, crosscontamination of the clean and dirty areas, and excessive heat build-up must be controlled. Traditionally, ventilation standards have been developed to control these conditions. Now, however, one other ingredient must be stressed: energy conservation. In each of these cases, it should be questioned how one can continue to accomplish the objective outlined above, yet prevent excessive energy use at the same time. Is it possible where air is being exhausted to control heat build-up, humidity, or odor, to condition the air so that it can be recirculated to other portions of the building (e.g., storage areas), and the heat content recovered? Can recirculation be practiced to a much greater extent (possibly even mandated) for hospital operating rooms? Comparison must be made of the ability of the various systems to meet the health and safety needs of the patient and personnel with a minimum of energy consumption. An example is cited from a recent study on the discharge of potentially toxic anesthetics from operating rooms.5 If these waste gases are discharged through the exhaust from the operating room, we are led back to the need for 100 per cent exhaust, similar to the time when flammable anesthetics were used. In this study, the authors not only consider the health effect of the waste anesthetic gases, but also, in a time AJPH October, 1978, Vol. 68, No. 10
COMMENTARY TABLE 1-Energy Consumption in Heating and Cooling Operating Room Air* (Energy Consumption, BTU's/Yeart)
Chicago Heating Cooling Houston Heating Cooling Los Angeles Heating
Cooling San Francisco Heating Cooling
Non-recirculating
Recirculating+
11.8 x 109 6.7 x 109
0.03 x 109 4.6 x 109
5.8 6.0
x 109 x 109
2.4 x 109 23.6 x 109
0.0+ 12.0 x 109
1.2 21.0
x 109 x 109
15.7
0.0± x 109
0.97 x 109 7.4 x 109
0.0+ 6.9 x 109
0.38 x 109 7.3 x 109
7.1
0.0 x 109
2.6 x 109 2.37 x 109
0.02.32 x 109
1.0 x 109 2.354 x 109
0.0 2.347 x 109
Heat Pipes
Thermal Wheels
0.59 x 109 5.2 x 109
tBased on air supplies at 550 F, 80 per cent RH, exhausted at 70° F, 50 per cent RH, with the room heating load assumed constant. Based on 24 hr/day usage, 65,000 cfm. +Assuming an optimum system that mixes supply and exhaust air in the appropriate ratio to minimize heating and cooling. The maximum recirculation was 80 per cent. ±The assumed constant heat load from the room was sufficient to heat incoming air. *Source: Piziali, et al. Ref. no. 5.
of sensitivity to energy consumption, compare various systems for conserving energy (Table 1). This study illustrates the types of comparisons that need to be made, and the need to consider public health concerns when comparing systems. The original reference5 should be consulted for further detail regarding interpretation of results.
Ventilation of Research Laboratories In turning attention from ventilation of hospitals to ventilation of research laboratories, we find similar consideration must be given to building and room air supply. Often, however, laboratory hoods gain the most attention when the topic of energy conservation and laboratory ventilation arises. This can be easily understood when one considers that the amount of heated air exhausted through a conventional laboratory fume hood is often in the vicinity of 1,000 to 1,500 cfm. Therefore, energy conservation proposals involving changes in laboratory hood operation are very tempting. This potential avenue for energy conservation must be approached very cautiously, however, so that we do not compromise what may be the most important safety device in a laboratory. Before one considers changes in operation of laboratory hoods, some thought needs to be given to the purpose of these hoods. Conventionally, we think of the fume hood as a device for exhausting toxic materials or flammable vapors during the course of an experiment. In most laboratories, however, these hoods may also be: a) used for temporary storage of a variety of chemicals, b) the source of exhaust for a flammable solvent storage cabinet located under or adjacent to the hood, or c) the means of disposing of small amounts of volatile solvents by evaporation. In addition, it must be remembered that research personnel do not follow a five-day a week, 8:00 a.m. to 5:00 p.m. work schedule, but AJPH October, 1978, Vol. 68, No. 10
often use laboratories during evenings and weekends. A temporary shut-down could decrease the efficiency of laboratory hoods, and could inadvertently expose laboratory personnel to chemical or fire hazards. The Department of Environmental Health and Safety staff at The University of Minnesota has concluded that changes in laboratory ventilation systems to conserve energy must be approached on a building-by-building basis. This method will require that someone become totally familiar with the design of the ventilation system and take measurements to determine operating characteristics of the system. Effective ventilation modification can then be individually tailored to meet specific system designs and operating characteristics. In existing buildings, a survey could be conducted to determine use of laboratory hoods; joint use might be arranged of some of the hoods that are underused, or some units could be shut down or sealed off. With sealing off an existing hood, however, evaluation must be made of potential adverse effects on ventilation balance in the laboratory or in the portion of the building in which the laboratory is located. Also, when buildings are connected via tunnels and corridors, interaction of ventilation systems and the changes in these interactions caused by changes in operation of ventilation systems in one or more of the buildings must be considered. Assuming that one proceeds cautiously, there are possibilities for energy conservation in laboratories. These include use of the heat in laboratory hood exhausts and recirculation of general room air. Another way to conserve energy from laboratory hoods is to include fewer hoods in the design of a new building. To accomplish this, consideration should be given to shared use of hoods by two or more laboratories. For example, a group of laboratories could be designed so the hoods, and possibly other shared facilities such as autoclaves and centrifuges, are near the hub of a group of
laboratories. 1013
COMMENTARY
The possible ventilation practices that could conserve energy involving laboratory hood ventilation include: use of heat exchange equipment; use of two-speed fans, and reduction of supply air. Heat exchange equipment in laboratories is the best system for both ensuring health and safety of personnel and conserving energy. It has the following advantages: * Keeping the hood velocities high at all times and eliminating any possible flammable or toxicological problems; * Conserving energy (heat) on a 24-hour basis; * Keeping a margin of safety for occupants by still providing 100 per cent make-up air; and * Being applicable to any exhaust air-general or fume hood exhaust. Two-speed fans can also be used to conserve energy. If this approach is used, face velocities of laboratory hoods when the facility is not being used must be at least 25 fpm to ensure that stored chemical agents present no flammable or toxicological hazard. For adequate removal of odors, vapors, and fumes from the general laboratory when the room is not in use, the room exhaust ventilation, provided by fume hoods, should not drop below 6 air changes per hour. A system to ensure full face velocity when hoods are in use must be an integral part of the two-speed fan system. An example of such a system would be one in which normal "high" fan speed is resumed in the laboratory when lights were turned on. It must be emphasized again that any ventilation changes, such as the installation of two-speed fans, must be scrutinized on a building-by-building, system-by-system basis. Variables such as the design of the existing air system, general ventilation characteristics of the facility, and hours that the facility is used are factors to be weighed when considering a two-speed fan system. The additional costs of ensuring health and safety via monitoring must also be considered in the feasibility study of this approach. A third energy conservation measure would be to reduce the supply air to the facility and maintain hood operation 24 hours a day. Supply air cannot be reduced to the point where hood face velocities drop below 25 fpm when the facility is not in use. Such a ventilation system also would require a control system to ensure "normal" supply air to the facility when in use. The possibility of recirculation of laboratory air, although attractive for energy conservation, presents a variety of potential health and safety problems. In facilities with biological, chemical, or other air contaminants (dusts, fumes, etc.), a recirculation system may not be applicable. Recirculation eliminates the safety factor of 100 per cent outside clean air continually diluting contaminants that could be generated inside the facility. The use of recirculation of air would have to be approached with great caution. Therefore, a recirculatip system is almost always limited to such areas as offices, classrooms, and the very few laboratory facilities that are free from airborne contaminants. A thorough monitoring program must be implemented to test, initially and periodically, the filtration systems in any recirculation system that is installed. In addition, an accurate and up-to-date 1014
report on how the facilities are used is mandatory when such facilities are recirculating air. Maintenance programs should be of fail-safe quality.* Complete shut-down of ventilation systems may also have implications in regard to fire safety in hosptiallresearch complexes. Recognizing that (particularly in a multi-story building) it is impractical to evacuate the entire building, compartmentalization of the building and control of smoke in the building may depend upon design of the ventilation system. For example, consider a building that is divided into four zones for ventilation. The fire alarm system may be designed so that if smoke is detected in the ductwork in one of the areas, the air supply to that area automatically shuts down. Air exhaust fans continue to operate and create a negative pressure in the area where the fire is located. At the same time, the ventilation for other zones of the buildings may be altered to include an increase in the quantity of air or a decrease in the quantity of exhaust air. This is to prevent smoke and gases from moving into zones that are outside the fire area. If there are portions of the day when ventilation systems are shut down, this early detection and compartmentalization of the building by ventilation would be compromised. In a building that is totally vacated during evening hours (when ventilation systems are shut down), this may not be of great consequence. However, in a medical/research complex, that includes patient-care areas, shutdown of portions of the ventilation systems for all unoccupied areas of the complex may seriously hamper the total fire protection system for the complex.
Miscellaneous Illumination is another area in which we have environmental health and safety concerns. Some of the areas of concern are building sanitation, patient safety, and employee
safety. 1. Building Sanitation. There must be sufficient lighting throughout hospitals so that personnel in housekeeping, maintenance, food service, and other areas who have responsibilities for cleanliness of the institution can do their jobs adequately. This would even include illumination for the more remote areas of the building, such as storage facilities for food and medical supplies, where adequate lighting may be important for cleanliness and insect and rodent control. There are standards that specify lighting levels for a variety of areas in the institutional environment. For example, food service standards specify lighting levels for food preparation surfaces, equipment and utensil washing areas, floors, refrigeration and dry food storage, and toilet areas. The primary reason given is that "ample light, properly distributed, makes dirt conspicuous, is necessary for the proper preparation and handling of food, and is imperative for the complete cleaning and sanitization of equipment and utensils."6 2. Patient Safety. With older patients in particular, there may be already some loss of visual acuity. This human factor, added to a decrease in quality or quantity of lighting, *Personal Communication from K. Carlson, Department of Environmental Health and Safety, University of Minnesota. AJPH October, 1978, Vol. 68, No. 10
COMMENTARY
will undoubtedly contribute to patient injuries resulting from slips and falls. Particular attention must be given to elimination of glare, and the provision of adequate light in areas where patients will frequent: adjacent to the bed, between the bed and bathroom, in the bathroom, in hallways, etc. When one examines patient injury statistics, these areas are where most of the injuries occur. Of course, there are also indirect implications to patient safety in non-patient areas of the hospital, such as areas where medications are prepared and where electronic equipment is maintained. 3. Such factors as contrast, brightness, and the amount of glare can be of importance to the safety of employees.7 If lighting is poor, additional physical energy will be required to perform job tasks. This may result in tiredness and increased possibility of an accident. As is true for patients, falls, and slips, and similar accidents can occur if light is improperly directed on corridors and steps. For such areas as the shops, glare and shiny surfaces may increase the hazard in the use of moving machinery. Recognition of the standard safety colors is an important concern, and Jensen reports that recognition is satisfactory down to a level as low as five foot candles. He recommends that it may be necessary to reexamine the OSHA (Occupational Safety and Health Administration) standard that recommends one half foot candle for safety lighting in active areas.7 Jensen also indicates that, according to the National Safety Council, 5 per cent of all industrial accidents are caused by insufficient lighting, and in 20 per cent of these cases, illumination and eye fatigue contributed to the accident.7 Another concern in the shop area is the stroboscopic effect of high intensity lights. When a high intensity lamp such as a mercury vapor lamp is used, brief, intense bursts of light energy may at times be in synchrony with the movement of a piece of shop equipment, such as a table saw. Hazard results when this synchronized movement gives the impression that the saw blade is standing still. To prevent this from happening, fixtures can be connected on three-phase wiring with alternate fixtures on different phases. The reason this is mentioned in conjunction with energy conservation is that high-intensity lamps may be substituted because they require less energy. 4. Emergency and outdoor lighting are two other areas that have received attention in the search for steps to conserve energy in institutions. The purpose of emergency lighting is to ensure, first, that one can find where the emergency exit is located, and second, that all surfaces are sufficiently lighted to prevent tripping or falling over objects that might be in the path of egress. The NFPA (National Fire Protection Association) standards require that the minimum lighting level in the path of egress be one foot candle.8 Energy conservation minded individuals may complain that a building appears to be excessively illuminated when, in fact, the quantity of light is only that required for emergency lighting. It should be remembered that emergency lighting must provide enough light to meet the requirement of one foot candle at the fringes of the area illuminated. Parking areas and other outdoor areas are of particular AJPH October, 1978, Vol. 68, No. 10
concern for employees in hospitals because of around-theclock shift changes. Some institutions have gone to the use of high intensity sodium lighting for outdoor lamps to increase efficiency of lighting without lowering intensity. Adequate lighting needs to be provided for accident prevention and for adequate security. Although there are some minimum standards for parking garage areas, this area of concern can only be evaluated on an individual basis, depending upon local circumstances.
Water Temperature The temperature of hot water is of critical concern, particularly in the hospital environment. The water that comes in direct contact with patients must not be too hot, generally less than 1100 F. In other areas of the institution, however, water used for cleaning and sanitizing must be hot enough to enhance the cleaning process and help provide sanitization. Areas where hotter water is needed include dishwashing, linen reprocessing, patient equipment processing, laboratory glassware washing, and animal cage washing. Animal cage washing, for example, usually requires water temperatures of 1400 F and 1800 F for adequate washing and sanitizing. This is not to say that some steps cannot be taken to conserve energy in the hot water supply system. Such steps can include designing systems for recirculation, and insulating pipes. In some instances it may be possible to lower hot water temperature. For example, temperature of water for laboratories in the classroom building might be lowered from 1400 F to 1100 F. With a booster heater, a similar lowering of temperature could be achieved in the food service facility. Hot water can be conserved by replacing old shower heads with the newer design that operates at a lower flow rate. If it is economically feasible, there could possibly be some heat recovery from water discharge from laundry machines. The temperatures in washing and sanitation cycles in laundry, dishwashing and glass washing, and cage washing machines, however, should remain at their present levels.
REFERENCES 1. American Hospital Association. Guide to the Health Care Field. AHA, Chicago, 1976. 2. U.S. Department of Health, Education, and Welfare. Energy Strategies for Health Care Institutions. April 1976. 3. Bond RG, Michaelson GS and DeRoos RL, ed: Environmental Health and Safety in Health-Care Facilities. New York: Macmillan, 1973. 4. Nightingale F: 3rd Ed. Notes on Hospitals. Longman, Roberts, and Green. London, 1863. 5. Piziali R, etal: Distribution of waste anesthetic gases in the operating room air. Anesthesiology, 45(5), November 1976. 6. U.S. Public Health Service. Food Service Sanitation Manual Including a Model Food Service Sanitation Ordinance. Pre-Publication revision, U.S. Department of Health, Education, and Welfare, 1976. 7. Jensen JH: The Role of Light and Radiant Energy in Health and Safety. Professional Safety, 12-16, April 1977. 8. American National Standards Institute. Practice for Industrial Lighting. 1430 Broadway, NY, 1973.
ACKNOWLEDGMENT This study was supported in part by contract HW-7405-Eng. 48, from the Energy Research and Development Administration, Washington, DC. 1015
