TEHRAN -- Up to 15% of sufferers find their acne flares up when they sweat a lot. This is probably due to water swelling the partial hair duct obstruction causing a complete blockage and therefore inflammation. The other question is if humid atmospheres make acne worse.

Yes. Going to a very humid climate on holidays, or working in an environment, such as a kitchen or steam room, can cause acne to flare up in the same way as it does in sweating. This is due to hydration and swelling of the ductile blockages, which precipitate the inflammatory phase of acne.