Appendix 18. Calculated values for sunlight exposure time (min) at specified solar UV-A intensities as a function of the remaining chlorine residual.

Appendix 18. Calculated values for sunlight exposure time (min) at specified solar UV-A intensities as a function of the remaining chlorine residual.
Remaining chlorine residual^a (%)	Solar UV-A intensity (W/m²)

	2.0	4.0	6.0	8.0	10.0	12.0	14.0	16.0	18.0	20.0	22.0	24.0

95	6.0	3.0	2.0	1.5	1.2	1.0	0.9	0.8	0.7	0.6	0.5	0.5
90	13	6.4	4.3	3.2	2.6	2.2	1.8	1.6	1.4	1.3	1.2	1.1
85	20	10	6.7	5.0	4.0	3.4	2.9	2.5	2.2	2.0	1.8	1.7
80	28	14	9.2	6.9	5.5	4.6	3.9	3.4	3.1	2.8	2.5	2.3
75	36	18	12	8.9	7.1	6.0	5.1	4.5	4.0	3.6	3.2	3.0
70	44	22	15	11	8.9	7.4	6.3	5.6	4.9	4.4	4.0	3.7
65	54	27	18	13	11	9.0	7.7	6.7	6.0	5.4	4.9	4.5
60	64	32	21	16	13	11	9.0	8.0	7.1	6.4	5.8	5.3
55	75	37	25	19	15	12	11	9.3	8.3	7.5	6.8	6.2
50	87	43	29	22	17	14	12	11	9.6	8.7	7.9	7.2
45	100	50	33	25	20	17	14	12	11	10	9.1	8.4
40	115	57	38	29	23	19	16	14	13	12	10	9.6
35	132	66	44	33	26	22	19	16	15	13	12	11
30	151	76	50	38	30	25	22	19	17	15	14	13
25	174	87	58	44	35	29	25	22	19	17	16	14
20	202	100	67	50	40	34	29	25	22	20	18	17
15	238	119	80	60	48	40	34	30	26	24	22	20
10	290	145	97	72	58	48	40	36	32	29	26	24
9	303	150	100	76	60	50	43	38	34	30	28	25
8	317	159	106	79	63	53	45	40	35	32	29	26
7	334	167	110	84	67	56	48	42	37	33	30	28
6	354	177	118	88	70	59	50	44	39	35	32	29
5	377	188	126	94	75	63	54	47	42	38	34	30
4	405	202	135	100	80	67	58	50	45	40	37	34
3	440	220	147	110	88	74	63	55	49	44	40	37
2	492	246	164	123	98	82	70	62	55	49	45	40
1	579	290	193	145	116	97	83	72	64	58	53	48
0.5	667	333	222	167	133	110	95	83	74	67	60	56
0.1	869	436	290	217	174	145	124	109	97	87	79	72
0.01	1 160	580	385	290	232	193	166	145	129	116	105	97
Note: Data were obtained using equation 10 and mean experimental values. ^aInitial chlorine residuals concentration was 1.5-7.5 mg/L.