SUMMARY GENERAL Results of routine monitoring of fallout in air, rain and milk samples during the gecond quarter 1969 are tabulated in this Report, Thene results are summarized on 4 quarterly basis and are preseated graphically in Fig, 2, together with resulta from previous Quarterly Reports during 1968 and 1969, Additional information on sample collection and evaluation, comparison of levels of environmental radioactivity and health hazard assessment is given in the Annual Summary Report ror 1968 "ENVIRONMENTAL RADIGACTIVITY IN NEW ZEALAND, Report No. NRL-F33"" which also includes the results of extended monitoring of fallout from the French nuclear tests in the Paoific, TOTAL BETA ACTIVITY ~ INDIVIDUAL STATIONS During the first quarter 1969, and also during the two previous quarters, levels of fiesion products in air and rainwater increased, These higher levels resulted (rom the 1968 series of nuclear tests conducted by France in the Pacific area between 8 July and 9 September, This series included for the first time the detonation of two liydrogen bombs, ~f# #o= The expected decrease in levels, which had been evident during the months following the previous test series of 1966 and 1967 occurred more slowly following the 1968 nuclear tests. ‘The total beta activity of air samples during the first quarter 1969 had not decreased siymificantly from the levels of the previous two quarterly perinds, There has been, however, a significant decrease during the second quarter 1969, The tatal beta activity of rain samples has steadily decreased since the third quarter 1968, The vreater delay in the reduction of fission product levels following the 1968 nuclear tests undoubtedly results from the injection of fission debris into higher altitudes when hydrogen bombs are detonated. debris is thus extended over u longer period, . The subsequent deposition of the The average levels_in air during the second quarter 1969 were 0.09 pci/m at Auckland and 0,06 pci/m at Wellington and Christchurch, periods in 1967 and 1968 the highest levels were 0.03 pci/n Christchurch) and 0,01 pCi/m (at Auckland) respectively, During the corresponding (at Auckland and The total deposition,in rain during the second quarter 1969 was 12.3 mCi/em* at Greymouth, and 5,4 mCi/km” the third quarter 1968, at Christchurch, The levels have steadily decreased since During the second quarters deposition was also at Greymouth: 4,7 and 2.3 mCi/km” gf 1967 and 1968 the highest respectively, SPECIFIC RADIONUCLIDES - COUNTRY-WIDE AVERAGES 1, SPRONTIUM-90 IN RAIN, The average deposition in rain decreased slightly from 0.34 mCi/km* during the first quarter 1969 to 0.27 mci/m* during the second quarter 1969, | This level is about one fifth of the highest lével previously recorded ie e. during the first quarter 1965, 2. STRONTIUM.89 IN RAIN, The average deposition reached a maximum of 5.1 mCi/kn” during October 1968, about one month after the conclusion of the 1968 nuclear tests. During,the second. quarter 1969 levels have been steadily falling: 0.5, 0.4 and 0.2 mCi/km during April, May and June respectively, The previous highest level was 305 mcd/km® during November 1966, 3e #STRONTIUM-90 IN MILK, The average level has increased slightly from 6.3 ‘otrontium Unite during the first quarter 1969 to 6,8 Strontium Units during the second quarter 1969, The highest level previously recorded was 15.9 Strontium Units during July-August 1964, The average level for the twelve months ending June 1969 (649 Strontium Units) is about 2% of the "permissible level" for the whole population ) 4e CAESIUM-137 IN MILK, The average level has decreased slightly from 33 pci/g K during the first quarter 1969 to 27 pci/g K during the second quarter 1969, The highest level previously recorded was 81 pCi/g K during March-April 1965. (The average level for the twelve months ending June 1969 (25 pCi/g K) is less than 0. wl of the "permissible level" for the whole population , | ; ( ope POTENTIAL HEALTH HAZARD = PAGE 3, IIIf - 8