Modified Perfluorocarbon Tracer Method for Measuring Effective Multizone Air Exchange Rates

Naohide Shinohara,Masashi Gamo,Koichi Takamine,Hirokazu Nishijima,Toshiyuki Kataoka,Michio Butsugan

doi:10.3390/ijerph7093348

Abstract

A modified procedure was developed for the measurement of the effective air exchange rate, which represents the relationship between the pollutants emitted from indoor sources and the residents’ level of exposure, by placing the dosers of tracer gas at locations that resemble indoor emission sources. To measure the 24-h-average effective air exchange rates in future surveys based on this procedure, a low-cost, easy-to-use perfluorocarbon tracer (PFT) doser with a stable dosing rate was developed by using double glass vials, a needle, a polyethylene-sintered filter, and a diffusion tube. Carbon molecular sieve cartridges and carbon disulfide (CS2) were used for passive sampling and extraction of the tracer gas, respectively. Recovery efficiencies, sampling rates, and lower detection limits for 24-h sampling of hexafluorobenzene, octafluorotoluene, and perfluoroallylbenzene were 40% ± 3%, 72% ± 5%, and 84% ± 6%; 10.5 ± 1.1, 14.4 ± 1.4, and 12.2 ± 0.49 mL min−1; and 0.20, 0.17, and 0.26 μg m−3, respectively.

Highlights

Since the 1990s, Japanese buildings have been designed to be more tightly sealed off from the external atmosphere
We developed a low-cost and easy-to-use doser with stable dosing rates because a large number of dosers of tracer gas are required in a large-scale survey of air exchange rates
CS2 was selected as the extraction liquid and HxFBz, OFT, and PFABz were selected as the tracer gases for three-zone air exchange measurement

Summary

Introduction

Since the 1990s, Japanese buildings have been designed to be more tightly sealed off from the external atmosphere. This has exacerbated indoor air pollution, leading to problems such as sick building syndrome and multiple chemical sensitivities in some houses in Japan [1]. To study the degree of the problem, researchers must conduct surveys of the air exchange rates in many houses. For such studies, it would be quite desirable to have a low-cost measurement device that can be operated by nonexperts such as the residents themselves. Useful data would be obtained if the device could separately measure the rates of exfiltration and infiltration between the indoor and outdoor environments (i.e., the indoor-outdoor air exchange rates) and those between the individual rooms (inter-room air exchange rates) over a period of time while the occupants continue with their usual life

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Conclusion