A study on Langat virus supports our hypothesis. Benbough [30] reported similar V-shaped curves of viability versus RH for Langat virus in aerosols composed of salt solutions. Of four RHs tested (i.e., ∼25%, 50%, 70%, and 95%), the minimum viabilities were ∼1% in NaCl and ∼10% in KCl, both at ∼50% RH, and zero in LiCl at RH<50%. Thus, the minimum viability of Langat virus in aerosols composed of an NaCl solution occurred at an RH close to the ERH of NaCl (i.e., 43±3%) [27]. KCl has an ERH of 59% [27], and this RH was not tested, so it is unknown whether the virus’ viability would have been lower at this RH. The ERH of LiCl, if it exists, is outside the range of RHs tested; its deliquescence RH is ∼11% [24].