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Three fundamental components determine the quality of air in any given location:
One indicator of adequate fresh air introduction (as well as contaminant removal) is the concentration of carbon dioxide in an area. There is a natural background concentration of carbon dioxide in the atmosphere which is rarely above 400 parts per million (ppm) by volume. As people breathe, carbon dioxide is produced which enters the indoor air environment. If there is insufficient air exchange (fresh air in - "stale" air out), the carbon dioxide levels rise. The legally permissible carbon dioxide concentration to which workers may be exposed for eight hours per day has been established by OSHA at 5000 ppm. IAQ guidance documents have established a recommended limit of 1000 ppm in indoor environments. The lower level has been recommended primarily because carbon dioxide buildup parallels that of other contaminants of greater concern (e.g., carbon monoxide, tobacco smoke, microorganisms, organic vapors).
Temperature and humidity are two factors that immediately affect people's perceptions of their environment, as well as their performance. Recommendations concerning these matters establish a work - rest regimen based upon the temperature and work load. For example, an office worker performing light duty (filing, typing, etc.) is generally allowed to work continuously in temperatures up to 86 degrees F. If the temperature rises to 87 degrees F, a 75% work - 25% rest regimen is suggested for each hour. Higher temperatures generally require additional recovery (rest) time. For purposes of IAQ, for workers typically clothed, it is recommended that summer temperatures be maintained between 73 degrees F - 79 degrees F, and 68 degrees F - 75 degrees F during the winter months. Relative humidity should be maintained below 70%.
There are many potential contaminants which could affect IAQ. Worker exposure to most hazardous materials is regulated by OSHA. Permissible Exposure Limits (PELs) have been established for hundreds of substances ranging from carbon monoxide to turpentine to common nuisance dust. Often, contaminants are generated from sources external to a particular indoor environment (e.g., paint fumes, truck exhaust, asphalt fumes). It is the position of the IAQ Committee that occupant's exposure to concentrations of airborne contaminants should be as low as reasonably achievable.
Other common contaminants of indoor air are bacteria and fungi (molds, mildew and yeasts). These microorganisms are always present in the air, but excessive concentrations may cause health problems. There are no enforceable standards establishing "safe" limits, but many IAQ professionals have recommended that levels exceeding 1000 colony forming units per cubic meter of air (CFU/m^3) suggest needed improvement or investigation of the indoor air conditions. High humidity, recent flooding, or free standing water are conditions which readily promote high concentrations of microorganisms in the air. These conditions often produce characteristic odors.
Exposure to significant concentrations of the bacterium Legionella pneumophila may cause an illness commonly known as Legionnaire's Disease. No confirmed cases of this disease have been diagnosed at University of Maryland to date. Past widely publicized incidents served to enlighten the campus community of the necessity for preventive action. Preventive measures have been implemented, and will remain in place, to prevent Legionella development in building air handling systems on campus.
The term "Sick Building Syndrome" has been used to describe a class of complaints characterized by nonspecific discomfort, headache, upper respiratory irritation, cough, dry or irritated skin, and sensitivity to odors. Sick Building Syndrome incidents have occurred more frequently in buildings that are exclusively mechanically ventilated. There are many suspected causes for this type of problem, but remedial ventilation alterations usually provide relief by supplying increased amounts of fresh air, or by removing more "used" indoor air.
Acceptable indoor air quality for University of Maryland buildings has been defined as air in which there are no known contaminants at harmful levels, and with which 80% or more of the occupants do not suffer systematic discomfort. The IAQ committee is committed to provide acceptable indoor air for all campus occupants. Successful investigation and remediation of IAQ problems sometimes involve sophisticated and complex techniques that require a great deal of time and expense. All reasonable effort will be made to correct problems in an expeditious manner. If problems cannot be corrected in a reasonable amount of time, the IAQ Committee will respond to the complainant and complainant's department head with an explanation for the delay.
Air testing is performed by Department of Environmental Safety Industrial Hygienists when evidence is suggested of contaminant presence. If air in your workplace is tested by Environmental Safety representatives, a report will be forwarded to you indicating the parameters or contaminants tested, results of sampling and the PELs (or recommended limits). Any recommended corrective actions will be forwarded to the Chair, IAQ Committee and your department head for action.
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