I've been a PVC collector for many years, and all my figurines were kept at pristine condition. As I was away for 2 weeks, I then noticed dust along the borders of the cabinet. It also forms clusters in sporadic locations. When I wiped it away, I saw the cloth was stained green. I was like, OMG, this is not good. I immediately took out every of my figurines, and indeed, some cheaper PVC alas had succumbed to colour erosion.
Please advise what should I do next.

1. Should I put lightings?
2. Change cabinet?
3. Frequent cleaning?
4. Any prevention?

Btw I'm staying in Taiping for a year now, and yes it is raining almost EVERYDAY. Is it because of moistures?