lexels and current ground level deposition in ground level air concentration in Canada ard the U. S. In response to the second question, a Health and Satety Laboratory Report (HASL-207 App) of gross gamma concentrations in surface air during 1968, ‘. observed_at 21 stations in both the Northern and Southern Hemispheres, indicated that the gamma radioactivity at Moosonee, Ontario, was only slightly lower (approximately 25%) than three stations in the U. S., namely, New York City, New York, Sterling, Virginia, and Miami, Florida. The analysis on all of these air samples was done in the Health and Safety Laboratory; thus, the results were comparable. As previously stated, gross beta air concentrations presently reported from Canada and U. S. Air Surveillance networks are not comparable due to difference in equipment used for analysis. Further, it would not be expected that there would be any correlation between past levels . a : . of deposited radioactivity and current levels of radioactivity in ground level air. Question 4D According to the Radiation Alert Network, gross beta radioanalysis of the | air is "insufficient to assess total human radiation exposure from fallout." Apparently, gross beta analysis fails to detéct tritium, carbon-14, iron-55, veryllium-7, manganese-5i, chromium-51, argon-57, and krypton-85, as well as all the alphaemitting nuclides like uranium, thorium, plutonium, radium, radon, and polonium-210. In your opinion, do the present systems of environmental monitoring provide sufficient data for anyone to comprehend the extent to which we are contaminating our environment? Answer 4D Information obtained from the U. S. Public Health Service Radiation