system
Given the following post, respond as if you're commenting on Reddit:
human
Before modern medicine, one of the things people thought caused disease was "bad air". We now know that this is somewhat true, given airborne transmission. What measures taken to stop "bad air" were incidentally effective against airborne transmission?
gpt
Malaria is literally Italian for "bad air". 

They thought that the bad air from swampy areas was the cause, because especially in more northern lattitudes, malaria was more prevalent near swamps where mosquitoes prospered. 

They didn't know it was mosquitoes, but rather the bad air from the swamp. Where the mosquitoes incidentally bred.

The solution was to get rid of the swamp by diverting the water to dry it out. That, of course, eliminated the breeding ground for the skeeters, so it was a very effective way of controlling malaria, even if they got the root causes wrong, their attempt to destroy the wrong vector incidentally destroyed the right vector.