1. Absence of evidence is not evidence of absence.

2. Risk is convex, so every risk increase by measures not taken is multiplicative, not additive.

The real question must be: does the disinfection do more harm than it provides reduction of risk.

> 2. Risk is convex, so every risk increase by measures not taken is multiplicative, not additive.

Wait. Is this true? f(x) = x^2 is convex but f(x+d) = f(x) + O(x). Are you saying that human risk assessment is estimated to be exponential?