Use of guideline and guidance values in the evaluation of indoor air problems

Introduction
The guideline and guidance values for contaminants in the indoor air of office environments are valuable tools for assessing occupants exposure to these compounds.

Methods
Reference values for fungi and bacteria, volatile organic compounds, formaldehyde, and man-made vitreous fibres were presented on the basis of a wide study conducted in office buildings. These values, guideline (P50) and guidance (P90, P100) values, can be used to assess the quality of indoor air in office environments with suspected indoor air problems. The procedure follows the basic assessment criteria proposed by ACGIH.

Results
The first step in the assessment is to collect and summarize the information gathered by previous surveys and from the environment. If an indoor air problem seems to be complicated and challenging, a multiprofessional approach is useful at the very beginning. Otherwise, the need for additional expertise is assessed during the evaluation. The first part of the evaluation ends with a preliminary hypothesis. In order to test the hypothesis, environmental samples are collected to determine suspected sources of agents, the quality and quantity of agents, and to demonstrate the release of contaminants from sources. The quality and function of building maintenance technology is studied simultaneously.

Discussion
Guideline and guidance values can be used simultaneously with other indoor environment factors for testing the hypothesis. The guideline (P50) and guidance (P90, P100) values help investigators to draw conclusions about the quality of indoor air and the exposure of occupants in office environments. However, conclusions usually have to be drawn multiprofessionally. Finally, it is important to note that the comprehensive procedure for solving indoor environment problems should always include the following three parts: (1) an evaluation of the perceived indoor environment and the health state of occupants; (2) indoor factors, measurement and analysis of indoor air quality; and (3) good practice in solving indoor air problems.