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EPA Building Air Quality Guide-1991

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Page 121 of 227

Common IAQ Measurements — A General Guide 109 Appendix A: Common IAQ Measurements - A General Guide The following is a brief introduction to making measurements that might be needed in the course of developing an IAQ profile or investigating an IAQ complaint. Emphasis has been placed on the param- eters most commonly of interest in non- research studies, highlighting the more practical methods and noting some inappropriate tests to avoid. Most of the instruments discussed in this section are relatively inexpensive and readily available from many local safety supply companies. Consult the guidance in Section 6 on pages 72-73 before determining whether to proceed with air sampling. OVERVIEW OF SAMPLING DEVICES Air contaminants of concern in IAQ can be measured by one or more of the following methods: Vacuum Pump: A vacuum pump with a known airflow rate draws air through collection devices, such as a filter (catches airborne particles), a sorbent tube (which attracts certain chemical vapors to a powder such as carbon), or an impinger (bubbles the contaminants through solution in a test tube). Tests originated for industrial environments typically need to be adjusted to a lower detection limit for IAQ work. Labs can be asked to report when trace levels of an identifiable contaminant are present below the limit of quantification and detection. In adapting an industrial hygiene sorbent tube sampling method for IAQ, the investigator must consider at least two important questions. First: are the emissions to be measured from a product's end use the same as those of concern SELECTING MEASUREMENT DEVICES The growing interest in indoor air quality is stimulating the development of instruments for IAQ research and building investigations. As you evaluate the available measurement devices, it may be helpful to consider the following criteria: Ease of use ■ portability ■ direct-reading vs. analysis required ■ ruggedness ■ time required for each measurement Quality assurance ■ availability of service and customer support ■ maintenance and calibration requirements Output ■ time-averaged vs. instantaneous readings ■ sensitivity ■ compatibility with computer or data logging accessories Cost ■ single use only vs. reusable ■ purchase vs. rental during manufacturing? Second: is it necessary to increase the air volume sampled? Such an increase may be needed to detect the presence of contaminants at the low concentrations usually found in non-industrial settings. For example, an investigator might have to increase sampling time from 30 minutes to 5 hours in order to detect a substance at the low concentrations found during IAQ investi- gations. In cases where standard sampling methods are changed, qualified industrial hygienists and chemists should be con- sulted to ensure that accuracy and preci- sion remain acceptable. Direct-reading Meter: Direct-reading meters estimate air concen- trations through one of several detection principles. These may report specific

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