Results Figure 2 shows the comparison of gamma exposure rates at 1 meter in air measured with LiF TLD dosimeters and a pressurized ion chamber. The TLD dosimeters were shielded against betas, and their responses reduced for background (mostly cosmic) as measured by controls. The ion chamber readings were reduced by 3.3 wR/hr, the cosmic contribution at that latitude (GU75). The dashed line represents a 1:1 relation between the two measurement techniques. The solid line is a linear regression of the data corrected for background, and yields agreement between the two methods within 4%. There is an offset of about 3 uR/hr between the data regression and a 1:1 relation, which probably indicates a difference of background subtraction methods between the two measurement techniques. Similar measurements made with a GM pancake probe shielded against beta contribution and compared with ion chamber readings resulted in a much wider data spread than for the TLD, due to poor statistics in the pancake probe readings (approximately 200 cpm/25 uR/hr). The linear relationship in the data does, however, indicate that the hand carry pancake GM probe could be used with some loss of precision in areas inaccessible to the ion chamber. The beta attenuation measurements made at seven locations are shown in Figure 3. Two experimental stands were placed in very thickly vegetated areas, such as closely packed clumps of grass 15 cm or more in height or thick patches of large-leaf vines. The top curve in Figure 3 represents these two stands; extrapolation of the data shows that only about 20% of the dose rate in air at a height of one meter is due to beta contribution. Two stands were placed in areas ef medium vegetation (15 cm or less in height, but mostly covered). IO0uZS