Assessment of Public Exposure to Electromagnetic Fields by Overhead Power Transmission Lines: A Case Study

Data collection of the electromagnetic field s (emf) produced by 33kv and 132kv power transmission lines were carried out in august 2003 at 3 different locations in kuching division , sarawak, malaysia. all read ings were take n at a slope distance of 3.5m, 7m, 10m, i5m , 20m, 30m, and 40m, respectively from the power lines . the emf values measured from the three locations of 33kv and 132kv line s were averaged to obtain the mean values of each distance from th e power lin es. for the 33kv power lin es, it was found that the mean emf valu es were 8,608 milligauss (mg ) at 3.5m away, 4,972mg (7m) , 785.5mg (10m) , 114.3mg (15m) , 41.6mg (20m), 6.1mg (30m) and 0.2mg (40m). for the 132kv power lines, the mean emf value s were gre ater than 20,000 miiligau ss (mg ) at 3.5m, 10,1612mg (7m), 4,164mg (10m) , 1.720mg (1sm), 802mg (20m) , 139mg(25m), 9mg (30m) , and 0.9mg (40m). the normal standard height of both 33kv and 132 kv power lines are 12 m above ground level and an casement width of 20 m on both sides of the power lines, and human activities generally occur at a distance greater than 50m (slope distance) from the power lines. it was found that the emf produced by both 33kv and 132kv power transmission lines do not pose adverse health effects on th e public who are generally exposed to emf levels below 4.0 mg.