if anything it increased humidity man, it rained for like four months straight
higher heat = more water transpiration.
temps stay the same though, ambient temps, and ambient humidity, the grow area isn't sealed at all.
think of like a barn or shed outside in the redwood rainforest..
also under that logic dual HPS would be pm free as well, and for yrs I ran those and always had pm.
the addition of the 600 Mh was the only difference.