el - s ee ae FIGURE 13.—Monitoring we Se Mea U.S. PUBLIC HEALTH SERVICE, DIVISION OF RADIOLOGICAL HEALTH PHOTO for external gamma radiation near the Test Site by U.S. Public Health Service personnel. Nevada instruments (fig. 13), chamber survey instruments, fallout trays and additional air samplers and recorders. Each vehicle was equipped with two-way voice radio communication. The number of teams used for each event was determined in advance by the predicted radiological situation, however five to ten teams was the usual number deployed. Up to 20 teams eould be organized within a short time, but were not normally maintained on a standby basis. Mobile ground monitoring teams are still maintained on a standby basis and used when needed. Air Sampling There were and are 30 permanent air sampling stations in operation 24 hours per day in the area surrounding the NTS at distances up to 180 miles. The air samplers used are high volume units, drawing air through an 8” x 10" glass fiber filter (fig. 14). When deemed desirable, a secondary activated charcoal cartridge is added for the collection of gaseous fission products. Flow rates are ap- proximately 50 cubic feet per minute (c.f.m.) for the glass fiber filter alone and 25 ¢c.f.m. with the charcoal cartridge added. 40