ABSTRACT
II. Exposure System Requirements 72 A. Environmental Factors 72 B. Ion Generation Techniques 73 C. Housing System Design 76
III. Recently Designed Small Animal Exposure Systems 79 A. The Rockefeller Exposure System 79 B. The Battelle Small Animal Exposure System 81
IV. Monitoring Exposure System Conditions 83
V. Interaction of Air Ions with Animals 84
References 88
72 Air Ions: Physical and Biological Aspects
I. INTRODUCTION
Carefully controlled experimentation on the effects of air ions on animal physiology began in the Air Ion Research Laboratory, University of California at Berkeley, in the late 1950s. Since then, dozens of other laboratories have continued experimentation in which animals are exposed to concentrations of air ions above normal ambient levels. In each case, the researcher had to develop an exposure chamber which was suitable for the purposes of his experiment. As we shall see in this chapter, the design of an exposure system is a complex subject and its successful performance may be affected by many design and environmental factors. Many of the systems described in the literature have not demonstrated the ability to generate ions in the quantities claimed. In some cases, no evaluation of the exposure conditions or system is possible, as the system is not described in detail or even at all. This failing in many of the early experiments has led to criticism of the accuracy of some reported results.'-'
Part of the problem of poor exposure system documentation was a result of the lack of sophisticated instrumentation for the measurement of static electric fields and extremely low levels of air ions. With more sophisticated instrumentation, which only recently has become available, and with the realization that careful measurement and documentation of the exposure conditions are vital, current research is providing valuable data on the biological effects of air ions. This chapter will not be a comprehensive review of exposure systems used in the literature nor should it be considered as a manual for the construction of an air ion exposure system. Instead, I will discuss what I believe are some important considerations to observe as one designs and builds an exposure system. When developing new exposure systems, the points brought up in this chapter should be addressed in some manner.
