Table 1. Ct values (mg-min/L) for inactivation of HPAI (H5N1) virus by free chlorine at 5ºC*.

Strain	pH	Log10 inactivation
		1.0	2.0	3.0
Hong Kong†	7	0.14	0.27	0.41
	8	0.26	0.53	0.79
Mongolia‡	7	0.13	0.26	0.39
	8	0.23	0.46	0.68

*Ct, 0.5(C₀ + C_0.5)/2 + C_0.5 [1–exp (–k (t–0.5) ]/k, where C₀ = chlorine concentration at time zero (mg/L); C_0.5, chlorine concentration at 0.5 min (mg/L); k, exponential chlorine decay rate; t = time (min). HPAI, highly pathogenic avian influenza.
†A/chicken/Hong Kong/D-0947/2006.
‡A/WhooperSwan/Mongolia/244/2005.