Comparison of residential power-frequency magnetic fields away from appliances in different countries

The purpose of this paper is to review measurements of residential power-fr equency magnetic fields made in different countries and to determine whethe r average magnetic fields away from appliances are higher in some countries than in others. The paper includes 27 studies reporting measurements of re sidential magnetic fields in samples of homes: 14 from North America, 5 fro m the United Kingdom, and 8 from other European countries. Various factors that might make the results from individual studies unrepresentative of ave rage fields in the relevant country are identified and discussed. Because d istributions of magnetic fields generally are approximately log-normal, the y are summarised by their geometric means. The best estimate of the geometr ic means of long-term average background fields in the United States is 60- 70 nT and in the United Kingdom approximately 36-39 nT. In other countries, there are insufficient studies to draw firm conclusions on average fields. Measurements of personal exposure are higher than measurements of backgrou nd fields, perhaps because they include exposures from appliances and other sources in the home. The ratio of personal exposure to background field se ems, on average, to be approximately 1.4. (C) 1999 Wiley-Liss, Inc.