Table 2. Prevalence ratios (PR, 95% confidence intervals) of weekly sick leaves among the personnel of schools and day care centres after the contamination of drinking water distribution system by contamination status of residence and workplace.

	Clean areaa (n = 174)			Contaminated areab (n = 187)
Week	PRc	95% CI		PRc	95% CI
−7 to −1 (ref)	1			1
0	0.90	0.56	1.42	1.21	0.80	1.85
+1	1.12	0.73	1.73	3.43	2.58	4.55
+2	1.10	0.71	1.73	2.89	2.14	3.89
+3	1.03	0.67	1.58	1.36	0.93	2.00
+4–12	1.16	0.88	1.55	1.23	0.96	1.61

^aResidence and workplace in the clean area;

^bResidence or workplace, or both, in the contaminated area;

^cModels adjusted for age and sex.