Effective Assessment and Diagnosis of Indoor Environment Quality Problems

Background: Indoor Environment Quality (IEQ) problems are typically characterized by non-specific symptoms complicated by a variety of extenuating circumstances. The assessment and diagnoses of IEQ problems fits poorly into the traditional occupational hygiene problem solving techniques. The objective of this presentation is to define the underlying complexity of IEQ problems with a theoretical model, describe the implications of this model on investigation activities and provide rationale for occupant based investigation techniques. Methods: Traditional methods for IEQ investigations include standard air quality measurements of temperature, relative humidity and carbon dioxide along with a review of the HVAC unit to assess whether the ventilation system in the building complies with ASHRAE standards. If unsuccessful at this screening stage, a more elaborate set of measurements may try to identify sources of volatile organic compounds, particulate and/or mould within the building. Based on the model provided, systematic surveys of occupant perceptions and symptoms have been used including hourly logs completed alongside datalogging measurement equipment. Results: Using the model described and data collected from over 100 workplaces, the relationships between identified model parameters such as ventilation, contaminants, job stress, and defined symptom outcomes are presented. Conclusions: The analysis of the data confirms the multi-factorial model presented. Given the centrality of occupant experience, the argument is presented that survey/log techniques should be an essential part in any investigation beyond the preliminary screening stage. The implications of this occupant/worker centered methodology are explored for occupational hygiene methods in general.