three aircraft, and some as many as 12 to 16; these differences in effective spray area are not reflected by the maps. A detailed study of the frequency of sprays in the Rung Sat Special Zone conducted by the NAS (1974) is shown in Figure 3-3.

For each herbicide mission, the date, number of gallons sprayed, and type of herbicide are indicated. These maps show how many times any

FIGURE 3-3 Herbicide spray missions (1966-1967) in the Rung Sat Special Zone. Data from HERBS tape include date of mission, number of gallons, and type of herbicide agent. SOURCE: NAS, 1974.