Fig. 2. Probable locations of patients when exposed. The part of the city shown in the graph is enclosed by a rectangle in the inset.  Cases numbers, in red, correspond to those in Table 1 and indicate probable daytime locations of patients during the period 2 to 6 April 1979. Of the 66 patients mapped as explained in the text, 62 mapped in the area shown. This distribution may be somewhat biased against residence locations because daytime workers not on vacation who both resided and worked in the high-risk zone are mapped at their workplaces. Proceeding from north to south, Compound 19, Compound 32 and the ceramics factory are outlined in yellow, The five patients residing in Compound 32 are mapped at their apartments. Within the compound, the placement of an additional, part-time resident and of the five reservists is arbitrary, as is that of the five residents and a nonresident employee in Compound 19. Patients known to have worked in the ceramics pipe shop are mapped in the eastern part of the factory area, where the pipe shop is located. Calculated contours of constant dosage are shown in black. Approximately 7000 people lived in the area bounded by the outermost contour of constant dosage, Compound 32, and the ceramics factory. The terrain slopes gently downward by about 40 m from Compound 19 to the ceramics factory.