Indoor air quality investigations: A practitioner's approach

Abstract

A practical strategy is outlined for investigating office environments in which the occupants are complaining about the indoor air quality and where traditional industrial hygiene TLVs cannot cope. In such situations, the available budget, time for conducting an investigation, and the monitoring resources are often quite limited. Attention focuses on ventilation, microorganisms, and volatile organic compounds (VOC). Ensuring proper functioning of the air handling unit is essential. Simple procedures are given for determining ventilation needs by measuring CO 2 concentrations. Complaints should be minimal if the fresh air supply is at least 10 L/S per occupant and the CO 2 concentration remains below 1000 μL/L. Coarse screening measurements are advocated for microorganisms and total VOC. Their purpose is to help define the general environmental conditions. If levels of nonspecific microorganisms exceed 500 colony forming units per m 3, then improvements in general housekeeping and sanitary conditions are advised. If the levels of total nonspecific VOC exceed 1 μL/L, then the VOC could be implicated in occupant dissatisfaction with air quality. Further action might include more definitive organic measurements, trying to locate and perhaps remove the strongest VOC sources, or increasing ventilation to dilute the VOC. If the screening measurements yield less than 500 CFU per m 3 and 1 μL/L for microorganisms and VOC, respectively, then further, more definitive, measurements will probably not be particularly useful.