Generally medical professionals do not vouch for using milk for tear gas despite it often being touted. The research seems to suggest they are largely the same in providing relief
Sources to back this up
That means bacteria can contaminate the milk and potentially cause infection if applied to eyes or skin wounds. Jordt says it’s better to use water or saline solutions to wash out eyes after a tear-gas attack
Another source of medical professionals recommending against it
And a study looking at pepper spray as well
In this study, there was no significant difference in pain relief provided by five different treatment regimens. [Water vs milk vs 3 other solutions] Time after exposure appeared to be the best predictor for decrease in pain.
There are perceptional reasons why it may feel like milk worked better such as it being cooled vs using room temperature water. Or from being the second thing used. Or from various different factors
But the research above suggests it doesn’t do as much as people think it does
The infection risks are not the same. Milk has stuff in it that microbes like for growing where water doesn’t have nearly all that. Other stuff can enter inside. The eye infection pathway is concerning especially right now when bird flu seems to enter that way and is in large quatities of dairy milk. Not all pasturization methods are certain to actually remove it (i.e flash pasturization might not)
Edit: A minor point to clarify, capsaicin is in pepper spray but not tear gas. They often do get conflated but they are different
For all the effort you’ve put into trying to convince people that water is the answer, it’s reasonable at this point to ask you to try it yourself. Get yourself some pepper spray from the store, and then spray your skin. Try to wash it off with water. Wait until you’re in sufficient pain and the water clearly didn’t do anything, then try milk, and feel your pain evaporate. You can do this experiment in less than an hour. Report back when you’re finished, or you can delete all this misinformation. Whichever.