Issue link: https://hi.iaq.net/i/630729
46 Section 6 OVERVIEW: CONDUCTING AN IAQ INVESTIGATION An IAQ investigation begins with one or more reasons for concern, such as occu- pant complaints. Some complaints can be resolved very simply (e.g., by asking a few common sense questions of occupants and facility staff during the walkthrough). At the other extreme, some problems could require detailed testing by an experienced IAQ professional. In this section "the investigator" refers to in-house staff responsible for conducting the IAQ investigation. The flowchart on page 45 shows that the IAQ investigation is a cycle of infor- mation-gathering, hypothesis formation, and hypothesis testing. The goal of the investigation is to understand the IAQ problem well enough so that you can solve it. Many IAQ problems have more than one cause and may respond to (or require) several corrective actions. Initial Walkthrough An initial walkthrough of the problem area provides information about all four of the basic factors influencing indoor air quality (occupants, HVAC system, pollutant pathways, and contaminant sources). The initial walkthrough may provide enough information to resolve the problem. At the least, it will direct further investigation. For example, if the complaint concerns an odor from an easily-identified source (e.g., cooking odors from a kitchen), you may want to study pollutant pathways as a next step, rather than interviewing occupants about their patterns of discomfort. Developing and Testing Hypotheses As you develop an understanding of how the building functions, where pollutant sources are located, and how pollutants move within the building, you may think of many "hypotheses," potential explana- tions of the IAQ complaint. Building occupants and operating staff are often a good source of ideas about the causes of the problem. For example, they can describe changes in the building that may have occurred shortly before the IAQ problem was noticed (e.g., relocated partitions, new furniture or equipment). Hypothesis development is a process of identifying and narrowing down possibilities by comparing them with your observations. Whenever a hypothesis suggests itself, it is reasonable to pause and consider it. Is the hypothesis consistent with the facts collected so far? You may be able to test your hypothesis by modifying the HVAC system or attempting to control the potential source or pollutant pathway to see whether you can relieve the symptoms or other condi- tions in the building. If your hypothesis successfully predicts the results of your manipulations, then you may be ready to take corrective action. Sometimes it is difficult or impossible to manipulate the factors you think are causing the IAQ problem; in that case, you may be able to test the hypothesis by trying to predict how building conditions will change over time (e.g., in response to extreme outdoor temperatures). Collecting Additional Information If your hypothesis does not seem to be a good predictor of what is happening in the building, you probably need to collect more information about the occupants, HVAC system, pollutant pathways, or contaminant sources. Under some circumstances, detailed or sophisticated measurements of pollutant concentrations or ventilation quantities may be required. Outside assistance may be needed if repeated efforts fail to produce a successful hypothesis or if the information required calls for instruments and procedures that are not available in-house. The IAQ investigation is often a repetitive cycle of information- gathering, hypothesis formation, and hypothesis testing.