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CEC Consultants' IAQ FAQ's can help get you up the IAQ Learning Curve. Got more questions? Call us at: (216) 749-2992.
1.
What is indoor air quality?
The goal of a ventilation systems is to maintain a healthy, safe, and comfortable environment with contaminants, humidity, fresh-air, and temperature in an optimal range. Back to top 2.
How does indoor air quality deteriorate? Sick Building Syndrome refers to those situations in which building occupants experience acute health and comfort effects that appear to be linked to time spent in a building, but no specific illness or cause can be identified. The complaints may be localized in a particular room or zone, or may be widespread throughout the building. Symptoms include:
With SBS, the cause of the symptoms is not known. Most of the complainants report relief soon after leaving the building. In contrast, the term Building Related Illness (BRI) is used when symptoms of diagnosable illness are identified and can be attributed directly to airborne building contaminants. Symptoms include:
The symptoms can be clinically defined and have clearly identifiable causes. Complainants may require prolonged recovery times after leaving the building. It is important to note that complaints may result from other causes. These may include an illness contracted outside the building, acute sensitivity (e.g., allergies), job related stress or dissatisfaction, and other psychosocial factors. Nevertheless, studies show that symptoms may be caused or exacerbated by indoor air quality problems. Back to top 4.
How common are indoor air quality-related problems? 5.
Why be concerned with indoor air quality-related problems? The following have been cited as causes of or contributing factors to Sick Building Syndrome:
Inadequate ventilation: In the early and mid 1900's, building ventilation standards called for approximately 15 cubic feet per minute (cfm) of outside air for each building occupant, primarily to dilute and remove body odors. As a result of the 1973 oil embargo, however, national energy conservation measures called for a reduction in the amount of outdoor air provided for ventilation to 5 cfm per occupant. In many cases these reduced outdoor air ventilation rates were found to be inadequate to maintain the health and comfort of building occupants. Inadequate ventilation, which may also occur if heating, ventilating, and air conditioning (HVAC) systems do not effectively distribute air to people in the building, is thought to be an important factor in SBS. In an effort to achieve acceptable IAQ while minimizing energy consumption, the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) recently revised its ventilation standard to provide a minimum of 15 cfm of outdoor air per person (20 cfm/person in office spaces). Up to 60 cfm/person may be required in some spaces (such as smoking lounges) depending on the activities that normally occur in that space (see ASHRAE Standard 62-1989). Some ventilation system design flaws include: Intermittent
air flow: Distribution
of air: Building
supply and exhaust locations: Proportion
of outdoor air: Periods of Operation: An HVAC system that begins to operate after building occupants have arrived,or shuts off before the end of the work day can cause an increase in building and occupant-generated pollutant levels. Similarly, if the system is off during periods of non-occupancy (e.g. at night and on weekends) building-generated pollutants may accumulate. Therefore, the ventilation system should be turned on several hours prior to occupancy, and shut down only after occupants have left. Back to #6 Maintenance:
HVAC systems must be properly maintained to promote indoor air quality.
If this is not done, ventilation systems can become a source of
contamination or become clogged and reduce or eliminate air flow.
Humidification and dehumidification systems must be kept clean to
prevent the growth of harmful bacteria and fungi. Failure to properly
treat the water in cooling towers to prevent growth of organisms,
such as Legionnella, may introduce such organisms into the HVAC
supply ducts and cause serious health problems. Accumulations of
water anywhere in the system may foster harmful biological growth
that can be distributed throughout the building. Chemical contaminants from indoor sources: Most indoor air pollution comes from sources inside the building. For example, adhesives, carpeting, upholstery, manufactured wood products, copy machines, pesticides, and cleaning agents may emit volatile organic compounds (VOCs), including formaldehyde. Environmental tobacco smoke contributes high levels of VOCs, other toxic compounds, and breathable particulate matter. Research shows that some VOCs can cause chronic and acute health effects at high concentrations, and some are known carcinogens. Low to moderate levels of multiple VOCs may also produce acute reactions. Combustion products such as carbon monoxide, nitrogen dioxide, as well as respirable particles, can come from unvented kerosene and gas space heaters, woodstoves, fireplaces and gas stoves. Back to #6 Chemical contaminants from outdoor sources: The outdoor air that enters a building can be a source of indoor air pollution. For example, pollutants from motor vehicle exhausts; plumbing vents, and building exhausts (e.g., bathrooms and kitchens) can enter the building through poorly located air intake vents, windows, and other openings. In addition, combustion products can enter a building from a nearby garage. Back to #6 Biological contaminants: Bacteria, molds, pollen, and viruses are types of biological contaminants. These contaminants may breed in stagnant water that has accumulated in ducts, humidifiers and drain pans, or where water has collected on ceiling tiles, carpeting, or insulation. Sometimes insects or bird droppings can be a source of biological contaminants. Physical symptoms related to biological contamination include cough, chest tightness, fever, chills, muscle aches, and allergic responses such as mucous membrane irritation and upper respiratory congestion. One indoor bacterium, Legionella, has caused both Legionnaire's Disease and Pontiac Fever. These elements may act in combination, and may supplement other complaints such as inadequate temperature, humidity, or lighting. Even after a building investigation, however, the specific causes of the complaints may remain unknown. Back to #6 Back to top 7. Do radon and asbestos contribute to indoor air quality-related
problems? 8. How do ventilation standards and building codes help protect
against indoor air quality related problems? Standard 62-1989 is a voluntary standard, which means that it becomes enforceable only after a state or locality adopts the standard in its building code. Furthermore, most current building codes pertaining to ventilation are standards only for the way buildings in a particular jurisdiction must be designed; they are not enforceable standards for the way the buildings are operated. A few states, through recently promulgated regulations, pending legislation, labor agreements and other mechanisms, are working to apply existing design codes and standards to building operations. Back to top 9. How do I locate the cause of indoor air quality problems?The first step is a building investigation. The goal of a building investigation is to identify and solve indoor air quality complaints in a way that prevents them from recurring and which avoids the creation of other problems. To achieve this goal, it is necessary for the investigator(s) to discover whether a complaint is actually related to indoor air quality, identify the cause of the complaint, and determine the most appropriate corrective actions. An indoor air quality investigation procedure is best characterized as a cycle of information gathering, hypothesis formation, and hypothesis testing. It generally begins with a walkthrough inspection of the problem area to provide information about the four basic factors that influence indoor air quality:
Preparation for a walkthrough should include:
The walkthrough itself entails visual inspection of critical building areas and consultation with occupants and staff. The initial walkthrough should allow the investigator to develop some possible explanations for the complaint. At this point, the investigator may have sufficient information to formulate a hypothesis, test the hypothesis, and see if the problem is solved. If it is, steps should be taken to ensure that it does not recur. However, if insufficient information is obtained from the walkthrough to construct a hypothesis, or if initial tests fail to reveal the problem, the investigator should move on to collect additional information to allow formulation of additional hypotheses. The process of formulating hypotheses, testing them, and evaluating them continues until the problem is solved. Back to top 10. Is air sampling the easiest way to identify indoor air quality problems?Although air sampling for contaminants might seem to be the logical response to occupant complaints, it seldom provides information about possible causes. While certain basic measurements, e.g., temperature, relative humidity, CO2, and air movement, can provide a useful "snapshot" of current building conditions, sampling for specific pollutant concentrations is often not required to solve the problem and can even be misleading. Contaminant concentration levels rarely exceed existing standards and guidelines even when occupants continue to report health complaints. Air sampling should not be undertaken until considerable information on the factors listed above has been collected, and any sampling strategy should be based on a comprehensive understanding of how the building operates and the nature of the complaints. Back to top 11.
How do I resolve indoor air quality problems? Pollutant source removal or modification: This is an effective approach to resolving an IAQ problem when sources are known and control is feasible. Examples include routine maintenance of HVAC systems, e.g., periodic cleaning or replacement of filters; replacement of water-stained ceiling tiles and carpeting; institution of smoking restrictions; venting contaminant source emissions to the outdoors; storage and use of paints, adhesives, solvents, and pesticides in well ventilated areas, and use of these pollutant sources during periods of non-occupancy; and allowing time for building materials in new or remodeled areas to off-gas pollutants before occupancy. Several of these options may be exercised at one time. Increasing ventilation rates and air distribution: This often can be a cost effective means of reducing indoor pollutant levels. HVAC systems should be designed, at a minimum, to meet ventilation standards in local building codes. However, many systems are not operated or maintained to ensure that these design ventilation rates are provided. In many buildings, IAQ can be improved by operating the HVAC system to at least its design standard, and to ASHRAE Standard 62-1989 if possible. When there are strong pollutant sources, local exhaust ventilation may be appropriate to exhaust contaminated air directly from the building. Local exhaust ventilation is particularly recommended to remove pollutants that accumulate in specific areas such as rest rooms, copy rooms, and printing facilities. (For a more detailed discussion of ventilation, read Indoor Air Facts No. 3R, Ventilation and Air Quality in Office Buildings.) Air cleaning: Air cleaners may be an important part of an HVAC system, but cannot adequately remove all of the pollutants typically found in indoor air. Air cleaners should only be considered as an adjunct to source control and ventilation. Air cleaners that have a high filter efficiency and are designed to handle large amounts of air are the best choice for use in office buildings. Air cleaners include the simple furnace filter, the electronic air cleaner,and the ion generator. Mechanical filters, either flat or pleated, are generally effective at removing particles. Flat filters collect large particles and pleated filters such as the high-efficiency particulate air (HEPA) filters collect the smaller, respirable particles. Electronic air cleaners and ion generators use an electronic charge to remove airborne particles. These devices may also produce ozone, a lung irritant. All air cleaners require periodic cleaning and filter replacement to function properly. In addition to removing particles, some air cleaners may remove gaseous pollutants. This is possible only if the air cleaner contains special material, such as activated charcoal, to facilitate removal of harmful gases. Although some of the devices which are designed to remove gaseous pollutants may be effective in removing specific pollutants from indoor air, none are expected to adequately remove all of the gaseous pollutants typically present in indoor air. Information is limited on the useful lifetime of these systems. They can be expensive and require frequent replacement of the filter media. Education and communication: These are important elements in both remedial and preventive indoor air quality management programs. When building occupants, management, and maintenance personnel fully communicate and understand the causes and consequences of IAQ problems, they can work more effectively together to prevent problems from occurring, or to solve them if they do. HVAC system operation and maintenance: Operate the ventilation system in a manner consistent with its design. Perform maintenance and inspections on a regular basis, as prescribed by the manufacturer. Record keeping: Maintain records of all HVAC system problems, as well as routine maintenance and inspection activities. Document the nature of complaints concerning the indoor air environment, as well as steps taken to remedy each complaint. These records may be useful in solving future problems. Occupant activities: Eliminate practices which may restrict air movement (e.g., furniture placement relative to air vents). Building maintenance activities: Increase ventilation rates during periods of increased pollution, e.g., during painting, renovation, and pesticides use;schedule use of pollutant sources to minimize the impact on indoor air quality. Ventilation standards and codes: Keep abreast of revisions to ventilation standards and building codes affected by those standards. Energy conservation: Re-examine energy conservation practices with regard to indoor air quality considerations, employee health, and productivity costs. Back to top Home
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