The sampling protocol and analytical procedures for airborne viable microorganisms in office environments are presented. Sampling strategy is outlined. The primary objective of sampling is to identify the sources of microorganisms so that corrective action may be taken. Sampling times, culture media, sample selection, calibration, and disinfection are discussed. Steps in the handling and processing of collected samples are described. These should have the input of a microbiologist or consultant experienced in microbiological techniques. Data interpretation is considered. Recommended remedial actions in cases where the total microorganism count exceeds 10,000 per cubic meter are given. These include removing stagnant water and slime from mechanical systems in the building, eliminating water spray systems in air handling units, substituting steam for cold water in humidifiers, eliminating the use of cold mist evaporators, maintaining the relative humidity below 70 percent, replacing heating, ventilation, and air conditioning system filters at scheduled intervals, providing adequate amounts of suitable outdoor air to reduce concentrations of microorganisms that may be shed by occupants, and reassigning affected or sensitized personnel to other work environments if necessary.
Environmental Investigations Branch, NIOSH, U.S. Department of Health and Human Services, Cincinnati, Ohio, 15 pages, 23 references