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Preface

reverses, the geomagnetic feld is estimated to weaken, and the changes in the last 200 years have been

potentially diminishing declines. Te magnetic poles are also moving, and it is estimated that the

north pole has moved 1,100 km over 170 years. Te simulation predicted that geomagnetic reversals

could enhance the oxygen escape rate by 3–4 orders only if the magnetic feld was extremely weak.

Consequently, it is estimated that global hypoxia might gradually kill numerous species. Te existence

of the geomagnetic feld is indispensible for the origin and evolution of life. Tis chapter presents fasci­

nating topics cocnerning the relationship between the geomagnetic feld declination and explosion and

extinction of life, and the impact of geomagnetic feld disturbance on human health.

Chapter 7 Safety Guidelines on Human Exposure to Electromagnetic

Fields (Kenichi Yamazaki and Tsukasa Shigemitsu)

In order for people to live and work safely and securely in today’s electromagnetic environment, it is

necessary that electromagnetic feld exposure have no efect. Tis chapter introduces a rationale of exist­

ing safety guidelines developed by international bodies such as ICNIRP (International Commission

on Non-Ionizing Radiation Protection) and IEEE (Institute of Electrical and Electronics Engineers). In

these safety guidelines, limit values are stipulated in terms of internal (in situ) electric feld for frequen­

cies lower than 10 MHz (ICNIRP) or 5 MHz (IEEE), and SAR (specifc absorption rate) for frequencies

higher than 100 kHz, based on biological efects of electric and magnetic felds, i.e., stimulation of nerves

for low frequencies and temperature increase for high frequencies. Issues of computational dosimetry

used to derive reference levels of electric and magnetic felds in these guidelines are also discussed.