Resistance to sunlight at 37°C based on F 99 values was in the following order: Salmonella Typhimurium > Escherichia coli > Shigella flexneri > Vibrio cholerae . The applicability of the reciprocity law indicates that fluence rate plays a secondary role in SODIS efficacy. Stating inactivation efficacy with T 90 or F 90 values without showing original data is inadequate for SODIS studies. Journal of Applied Microbiology 2006, 101 828-836.