Heath Promotion Directorate, Health Canada, 1995. Wilson, J.B., et al. Verocytotoxigenic Escherichia Coli Infection on Dairy Farms in Southern Ontario. In Recent Advances in Verocytotoxin-producing Escherichia Coli Infections , M.A. Karmali and A.G. Goglio, editors. Elsevier Science B.V., 1994.
Wind affects the freeze factor.