I spent a couple summers working at a printer in Massachusetts around 2005-2006 and the first year the shop did not have air conditioning. The paper came off a large roll at the back of the press which was pulled through from the front. Part of the process involved sending it through an oven presumably to set the ink, then it would go over a chilled roller to cool it off again. On particularly hot and humid days it would be difficult to restart the press after stopping it as the condensation on the chilled rollers would saturate the paper and it would immediately rip (referred to as a "tear out") and would then have to be manually spliced back together with tape. One night we spent something like 10 hours trying to get the press started up again after stopping it to change the plates.

Anyway, that's just my story about humidity and printing. The second summer I worked there they had installed air conditioning and those problems went away. I'm sure they did it for business reasons and not because they thought it was cruel to force people to regularly work in 100+ fahrenheit temperatures.