There are two things that you need buying if you are moving to Korea.
1). If the studio that you are renting doesn’t have central air conditioning then a dehumidifier is necessary. If you don’t buying it, then the humidity level in the flat will go up to very high levels. Your clothes will not be drying and there is a risk of mold in your flat. I usually running the dehumidifier 3 hours after taking a shower. Then the flat is dry an there is no molding problem.
2). Because of the bad air quality, I bought it air cleaner, it should have a Hepa-filter. I have it on continuously, from October until April. When I’m at home, then I knows that the air quality is good. The important thing, for the lungs is that the average time of pollution is low. So even you are exposed at high levels for short time outside, then it’s okay because it’s good quality at yours home.