A proactive approach for managing indoor air quality.

Introduction

A substantial body of literature shows that the factors most often implicated in indoor air quality (IAQ) investigations are ventilation and maintenance related (1-9). The attribution of sick building syndrome (SBS) primarily to insufficient or poorly distributed ventilation air is supported by the large number of studies conducted by the National Institute of Occupational Health and Safety (NIOSH) (10). Inadequate ventilation was a predominant feature in many of these building studies and in other published reports, which identify it as an important factor (5-10). Several heating, ventilating, and air-conditioning (HVAC) components are cited frequently as the loci of IAQ problems because they provide the opportunity for biological growth and bioaerosol generation in the presence of moisture. Such excessive moisture is often caused by poor design and poor control of humidity, as well as inadequately maintained cooling coils and drain pans. IAQ problems are exacerbated by accumulated dust and by the presence of fibrous insulation in the ventilation system (1).

"Psychosocial" aspects, which include lighting, ergonomics, acoustics, personal sensitivity, and social factors have also been shown to play a major role in IAQ (11-16). Complaints of thermal discomfort, inadequate ventilation, or indoor air pollutants may actually be caused or complicated by psychosocial factors (13). For example, poor lighting (glare, flicker, poor illumination) can produce symptoms such as eyestrain and headaches that are similar to symptoms resulting from IAQ problems (low humidity, volatile organic compounds [VOCs], formaldehyde) and can thus be misinterpreted as an IAQ problem. In many cases, psychosocial factors involve occupant distrust of building management that results from perceived inaction or insensitivity to complaints (6). An increased likelihood of complaints has been documented when occupants have little or no control over their environment (17). Furthermore, psychosocial factors may be the underlying reason many investigations conclude without identifying an exact cause for the complaint. For example, the Ontario ministries of Labour and Governmental Services have investigated more than 2,000 IAQ complaints since 1976. In many of these cases, the cause of the symptoms could not be found (18). Similarly, a NIOSH study of 446 building investigations found that in 13 percent of the cases the cause was unknown (19). Instead of identifying the true source of the problem, the investigator is often left with a long list of unsolved problems.

To compound the problem, currently used investigation protocols are often ineffective (20). Reasons for this problem include the lack of established IAQ exposure standards, insufficient research on low-level multiple contaminants, and the variety of building designs and ventilation systems. These kinds of difficulties result in costly studies that produce no conclusions and that may lead to irresponsible speculation.

Since many IAQ investigations are ineffective and fail to resolve IAQ problems, prevention would be the best solution. Specifically, a proactive approach is needed that addresses the two causes (HVAC and maintenance) most often implicated in IAQ investigations. The literature has suggested a limited number of proactive approaches that generally address both the ventilation system and occupant perception (2, 13, 21-23). In most cases, however, these approaches require technical expertise and generate excessive paperwork. The approach proposed below is designed to be implemented by a building manager and requires only a limited technical background.

Proactive Protocol Outline

The following outline for a proactive approach is designed to prevent IAQ problems. This protocol is empirically based on the causes most often implicated in IAQ complaint investigations, the HVAC system and psychosocial aspects, and is designed to be implemented by in-house personnel (i.e., building maintenance and facility managers). In addition, procedures for handling and logging IAQ complaints and suggestions for conducting an initial investigation are included. Thus, this proactive protocol adopts a threefold approach to preventing IAQ problems: HVAC system maintenance and operation, psychosocial aspects, and complaint handling. Refer to Figure 1 for a flow diagram of the protocol. The protocol incorporates the U.S. Environmental Protection Agency's (U.S. EPA's) document "Building Air Quality," its IAQ profile and IAQ manager concepts, and an environmental survey designed by Rohle et al. (13, 14). The IAQ profile and IAQ manager are included in the initial stage for the collection of building information. The environmental survey is used in the psychosocial portion of the protocol to address occupant perception and HVAC maintenance. The aim of this proactive protocol is to provide a cost-effective guide for preventing IAQ problems in nonindustrial settings and in buildings in which there are no current IAQ complaints. An attempt has been made to keep this protocol flexible so that it can be implemented in a variety of buildings. A basic understanding of the building HVAC system and its operation is expected of those who will implement the protocol.

Designation of an IAQ Manager and Background Information Collection

The first step in this approach is to identify a knowledgeable individual as the building IAQ manager. The primary function of the IAQ manager is to designate a knowledgeable person to oversee the entire IAQ program and to collect background information on the building. The IAQ manager is also responsible for the implementation of the psychosocial, HVAC system maintenance, and initial investigation aspects of the protocol. This can be accomplished using U.S. EPA's IAQ profile, which is a three-step process: (1) collection and review of existing building records (e.g., construction and operating documents, maintenance records, complaint histories); (2) a walk-through inspection to identify potential problems indoors and outdoors; and (3) the collection of detailed information on the HVAC system, occupant demographics, and building activities (13). The IAQ manager compiles this information, which should provide him or her with an understanding of the building's layout and intended function. During the walk-through inspection, specific attention should be paid to occupant activities, building functions, IAQ problem indicators, and potential source identification. It is very important to inform all appropriate personnel (e.g., HVAC engineering, housekeeping, and maintenance staff) to notify the IAQ manager about IAQ-related problems or potential problems (13). These personnel should also be included in occupant education and awareness programs, which are discussed in the psychosocial component of this protocol. This entire procedure is designed to be a front-end process providing the IAQ manager with information needed to anticipate, prevent, and handle IAQ problems.

HVAC System Maintenance

The HVAC maintenance portion of the protocol focuses on the proper maintenance and evaluation of the HVAC system, while emphasizing the components most often implicated in IAQ studies. The training of building maintenance personnel also should be incorporated into the maintenance program. The program should begin with the collection of any available documents that describe the operation of the HVAC system, including original construction plans and specifications, approved shop drawings of all equipment and environmental systems, commissioning reports, operating manuals, and test and balance reports (24). These should be available from the background information collection of the IAQ profile stage. This information will allow the IAQ manager to understand both the capabilities and the limitations of the building's HVAC system. The maintenance program should include not only regular inspection and maintenance of system components (air handling units, drain pans, ductwork, supply/return diffusers) and documentation of these activities, but also, regular proactive maintenance including filter changes, coil cleaning, decontamination of microbial growth, and overall HVAC system cleaning, on an as-needed basis. Special attention should be paid to locations of high relative humidity in the system; these areas must be kept free from dust and dirt, since the combination of high humidity and dirt has been shown to provide an opportunity for microbial growth. Importantly, the IAQ manager also should monitor changes in contaminant loads or building activities that may require subsequent changes to be made in the HVAC system. Collectively, these routine maintenance procedures should enhance energy efficiency and the life span of the HVAC equipment while providing acceptable environmental conditions in the occupied spaces.

A successful proactive maintenance program for IAQ requires an understanding of the basic principles of mechanical cooling and ventilation systems and a formal introduction to HVAC theory. The IAQ manager should have at least a basic understanding of psychrometry and should be familiar with the psychrometric chart. By describing the operation of a building HVAC system graphically on this chart, the IAQ manager can determine the conditions that should exist throughout the system, both in occupied spaces and in each component of the system. The IAQ manager can then determine from the chart the characteristics of all points in the system and identify those points where the relative humidity can exceed 75 percent. Such information should be used to verify that existing room conditions fall within the acceptable range, that ventilation air is entering the building, and that supply air conditions are appropriate (25).

The next step in developing a proactive maintenance plan involves a thorough review of the HVAC system. The following description covers systems with air-handling units and ductwork; systems utilizing terminal fan coil units should be treated similarly. A schematic drawing should be developed to depict the HVAC system, including all air-side equipment components and ductwork. Each location where air is mixed, cooled and dehumidified, or heated must be located, and plans must be made to monitor the condition of the air at each of these points. The individual components of the system must then be reviewed, and potential problem areas must be identified.

Under design cooling conditions in ducted HVAC systems, high relative humidity normally exists only in equipment from the cooling coil section to the room supply outlets. Outside air and mixed outside/return air will occasionally undergo conditions of high relative humidity, so these locations, which transport unfiltered air, should also be monitored periodically (26). Any duct work lined with insulation, even if the lining is impregnated with a biocide, will support fungal growth, so lined ductwork should also be monitored routinely (27).

The filter section, like the outside/return air duct, may experience high relative humidity. Generally, this section has a relative humidity below 75 percent, but it should be monitored for microbial growth since dust is always present in filters. Each HVAC system should be fitted with filters that remove dust and dirt to prevent accumulation in the system ductwork, where dirt can provide a haven for microbial growth (28).

The next component of the system is the coil section; from this location until the air enters the room, the relative humidity of the air stream is routinely above 75 percent during the cooling season. As a result, all system components and ductwork downstream of the coils must be kept clean and free from conditions that could promote microbial growth. The cooling-coil section must be provided with drainage piping and installed at an angle to ensure that the drain pan sump remains as dry as possible. The interior insulation and lining of the coil section must be observed carefully to monitor the formation of unwanted growth in the cooling mode. Cooling-coil cleaning should be aggressive, and coils should be checked routinely for air-side fouling. The cleaning agents must be selected and the cleaning operations must be timed to ensure the safety of building occupants.

In conventional draw-through HVAC systems, air flows through the cooling coil before entering the fan section. In this configuration, the fan section experiences the same conditions as the cooling coil section and should be monitored and cleaned frequently. In a blow-through fan configuration, the fan section is not subjected to saturated air conditions, but it does occasionally experience over 75 percent relative humidity conditions similar to outside air and outside/return air duct systems.

The supply ductwork of the system undergoes very high relative humidity conditions during the cooling season. Most existing buildings are not equipped with provisions to monitor or clean the interiors of such ducts, and any attempt to install access panels or clean the duct interior may prove to be prohibitively expensive. This proactive maintenance program should include cleaning of supply ducts only where possible without major changes to the duct system.

The final step in preparing a proactive maintenance protocol involves establishing formal procedures to implement and track the maintenance plan. These procedures include the paperwork and recording methods (checklists) that enable the IAQ manager to monitor and operate the system to provide comfort and safety for building occupants. Responsibility lies with the IAQ manager to ensure that maintenance is being performed properly, through review of maintenance checklists and random HVAC system inspections.

Operational Protocols

The IAQ manager must also monitor the building HVAC system controls to prevent unconditioned outside air from entering the building. This requirement is especially critical when a building is unoccupied and the refrigeration system is off. The exhaust fans should be turned off when the HVAC system is placed in the unoccupied mode to prevent raw air from being drawn into the building and creating high relative humidity conditions. During normal system operation when the building is occupied, the outside air damper should be set so that slightly more air is introduced into the building than is exhausted; this arrangement establishes a slight positive pressure in the building. In addition, the IAQ manager must visually inspect all cold surfaces in the building, including refrigerant piping, cold-water and chilled-water piping, supply ductwork, outside air ductwork, and horizontal interior rainwater leaders, for evidence of moisture formation. These inspections should be especially thorough in areas above suspended ceilings; a proactive maintenance program should identify defective insulation and take corrective action long before the stain appears on the ceiling.

Although no maintenance procedures will allow a poorly designed or grossly misapplied system to function properly, this aggressive and proactive program should enable a majority of buildings to operate productively and safely, In many existing buildings, the extent to which HVAC systems can respond to these operational requirements is limited: nevertheless, a carefully crafted and supervised program should produce the best indoor air conditions possible. In addition, such a program can provide the information necessary to identify and predict conditions that are beyond the ability of the HVAC system to accommodate.

Psychosocial Aspects

The protocol addresses psychosocial factors with an occupant survey and an occupant education and awareness program. The environmental survey was originally developed by Rohles et al. and employs a rating scale based on four major attributes of the indoor environment: acoustics, air quality, lighting, and thermal aspect (14). The survey has been slightly modified from the original version to enhance its acceptance by building occupants [ILLUSTRATION FOR FIGURE 2 OMITTED]. The purpose of the survey is to rate the acceptability of the workplace environment and to identify any potential IAQ problems as early as possible. Furthermore, the survey indicates to all occupants that their health and well-being are being taken seriously and may address the concerns of the most sensitive occupants. Most important, however, is the prevention of many of the psychological and social ramifications associated with the subjective aspects of IAQ problems. Other advantages of the survey include improved labor-management relations and increased employee communication.

The environmental survey should be distributed quarterly by the IAQ manager. The amber of occupants to be surveyed depends on the total number of occupants present in the facility. Occupants are chosen randomly and consequently are representative of the occupant population. Before they receive the survey, the chosen occupants should be notified by memo or other appropriate media, such as e-mail, brief meetings, or bulletin boards. The notification should explain the purpose of the survey and include directions on how and when to complete it. In addition, the notification should mention that IAQ awareness information will be posted periodically to educate and inform occupants about IAQ. The name and number of the IAQ manager should be included in case the occupants have questions. After the survey is distributed, a reasonable amount of time should be allowed for its return, as stipulated in the notification.

When the surveys have been collected, the IAQ manager should interpret the results. The results of each survey can be calculated simply by adding up the values for the 10 items and calculating an average. Then, the percentage "acceptable" is calculated by dividing the total number of surveys with an acceptability rating greater than four by the total number of surveys distributed and multiplying by 100 (14).

If the percentage acceptable is 80 percent or above, the IAQ of the building may be considered acceptable by definition. The IAQ manager must, however, pay special attention to any ratings less than three, even if the overall rating is acceptable. Using a standard interview form, the IAQ manager should immediately follow up with the appropriate occupant(s) to inquire into the possible reason for the low rating. In addition, the IAQ manager should pay close attention to the comment section of the survey. If the comment section lists any symptoms common to building-related illness (BRI), the occupant should immediately be referred to a physician experienced in treating BRI. Furthermore, the IAQ manager should look for clues in the comments that may lead to the identification of the problem. Referring to the background information collected on source identification and occupant activities may be helpful in determining any possible connections.

If the overall acceptability rating of the surveys is below 80 percent, there may be an IAQ problem. The steps outlined in the preceding paragraph should be taken in addition to the initial investigation procedures. Refer to the discussion of complaint investigation below for additional guidance.

A potential problem with the survey is interpretation of the results. It may require a person trained in IAQ to decide if an actual problem exists or if the complaints are the result of personal sensitivity. The IAQ manager must use professional judgment when analyzing the survey results.

Time is of the essence in IAQ investigations. Follow-up should be conducted as soon as reasonably possible to prevent "IAQ rumors," to reduce memory bias, and to reinforce the message that management has concern for the employee. Otherwise, the purpose of the survey - to address the psychosocial aspects of IAQ - is defeated. Finally, all complaints should be recorded in a complaint log.

Another component of the psychosocial portion of this protocol is a program to promote employee education and awareness. The following subjects should be addressed in the education and awareness program: IAQ issues, common problems, the history of IAQ, who is affected, how occupants are affected, common symptoms, illnesses, the role of the IAQ manager, communication (whom to contact in the event of a problem and how to report complaints), common causes of poor IAQ, and why addressing IAQ proactively (occupant health and productivity) is important. The IAQ manager should address all these issues by communicating with occupants through an appropriate medium while taking care not to alarm them. A separate but important aspect of the education and awareness program involves the training of maintenance personnel in HVAC principles. HVAC training should cover all aspects of psychrometries, system operation, and maintenance that affect IAQ.

Complaint Handling and Investigation

This portion of the protocol involves the documentation and initial investigation of an IAQ complaint. Again, the IAQ manager must use judgment about when to initiate a formal investigation. Every complaint, whether investigated or not, should be documented for future reference. The process begins with the recording of complaints and proceeds with an initial investigation protocol.

Building occupants must know to report complaints to the IAQ manager. All complaints should be recorded on a standardized complaint form administered by the IAQ manager and completed by the occupant making the complaint. The IAQ manager should record each complaint for record keeping and then investigate the problem. All complaints may not warrant a complete investigation, but showing occupants that their concerns are being taken seriously is very important. The IAQ manager should determine the appropriate degree of inquiry.

The purpose of the initial investigation is to determine the general scope of the problem, to establish the existence of the problem, to identify and solve the problem, or to direct further investigation should outside assistance be required. No measurements are taken during the initial investigation. Before the initial investigation begins, it may be useful to refer to the background information on the building collected during the IAQ profile stage.

The initial investigation should begin with an interview of the complainant. A standardized questionnaire can be used if the number of complaints is excessively high. Occupant interviews or questionnaires are intended to characterize the building occupants, their complaints, and reported symptoms. Plotting the location of the complaints on a floor plan of the building may also be helpful. This will provide a graphic representation of how the complaints are distributed throughout the building and should help determine whether the problem is widespread or localized. If likely causes are identified at this point or at any of the following stages, corrective action and mitigation measures can be implemented immediately. Otherwise, the interpretation of previously obtained information leads the investigation. Furthermore, at any point during the investigation, the IAQ manager should be prepared to seek outside assistance.

The walk-through inspection involves a thorough examination of the facility, both indoors and outdoors, to help identify the cause of the IAQ complaint. This is accomplished by inspecting the HVAC system and identifying possible sources of IAQ problems in the building. For the majority of IAQ problems, the ventilation system is directly or indirectly involved. Therefore, an understanding of the ventilation system and operation is an essential step in all IAQ investigations. The HVAC system is evaluated through review of pertinent documents and inspection of HVAC system components. A list of the common sources of IAQ problems, including their causes and solutions, should be developed and referred to in the walk-through.

At this stage of the investigation, specific problems may have become evident, and outside assistance may be required. This stage also involves a report or summary of the findings and recommendations about control and prevention of causes implicated during the investigation. This report will either indicate the successful solution to the IAQ problem or form the basis for further study by outside consultants.

Conclusion

This paper presents a framework upon which to build a proactive IAQ protocol. This protocol uses a three-phase approach to anticipate, prevent, and manage IAQ problems. The protocol is based on the causes most often implicated in IAQ investigations and is intended to be used by in-house personnel. The next step is to refine, implement and then evaluate the effectiveness of the protocol.

As we await the necessary research on low-level exposure risks from indoor air contaminants, as well as the revised Standard 621989R from the American Society of Heating, Refrigerating and Air-Conditioning Engineers, prudent HVAC system maintenance and evaluation may provide an unwritten insurance policy for building owners and HVAC system designers (29). Addressing occupant perception of IAQ may prevent many of the subjective problems so often associated with IAQ from occurring. The benefits of this protocol may include decreased energy costs and decreased deterioration of equipment through proper maintenance, potential increases in productivity from decreased absenteeism, and litigation prevention. For building owners and managers, the reputation of having good IAQ can improve the marketability of buildings. By contrast, addressing IAQ complaints reactively rather than proactively can be very expensive, especially when outside consultants, along with costly measurements and laboratory analyses, are required.

Corresponding Author: Dr. Phillip L. Williams, Environmental Health Science, College of Agricultural and Environmental Sciences, University of Georgia, Athens, GA 30602-2102.

Acknowledgements

This research was supported by the Georgia Power Company and the University of Georgia's Agricultural Experiment Station.

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