“ ” by as u-*~ cloud or when changes occur. be determined by trial. should be collected with the Cascade As 4 \ Frequency of readings will etor for one altitude. ight within the c the duration If it appears that several can be made, the impactor showtc be reo first operdted. only the altitude at which it was The 1,000 c.f.m. samplers will be operated simultaneously for periods of 30 minutes. Filters will be changed on alternate 15 minute periods. As each filter is removed from the sampler, it will be rolled into a cylinder and inserted in the survey meter probe. One reading should be recorded immediately and a second after a five minute wait. After this check, the filter will be placed in an envelope and identified. Be Ground Team When a firm estimate of the cloud's path is available, the ground team will be dispatched to three airports across the path. Ground team unit #1 will be deployed so that two men with equipment are at each airport. One of the three stations will be designated field HQ and in this station, the NYO member will establish himself with the reserve and special apparatus. As soon as the three stations have been established, HQ should be informed of the fact. Unit #2 will stand by at this field until instructed by HQ to man a second set of sampling stations. 1. Sampling Procedure - General: Each of the ground sampling stations will be equipped with two Hi Volume samplers, a fall out tray and gummed paper frame. The HQ station will have, in addition, a Cascade Impactor which can be used on the ground and in the C-l7. ny ‘ “~ , Background sampling should be started immediately after the stations are established. A continuous sample with each piece of equipment should be run unti 7o/nours before the predicted arrival of the cloud. For the duration of the cloud's passage, Hi Volume samples should be collected in pairs every_two hours simultaneously at all stations, and the tray and gummed paper samples collected every 2h hours.~2 These sampling periods may be modified by HQ. Each sample should be stapled to a separate data sheet. Samples should be air mailed to NYO twice each day from each . station in the envelopes provided. DORARCHIVES4