If you live in Shanghai or any particularly humid areas, leave some windows open when you leave for traveling two months. The advice matters even more so if you live on the first floor.
Having come from a very dry area of the world, I am still getting use to humidity. Humidity not only cause excessive sweating (even while I remain motionless), it also makes my house very moldy. While I have a preference for being green, I have on occasion bring out the bleach to combat mold issues.
Having left Shanghai for 2 months, and making the mistake of closing all the windows, I came home to this:
Ok. Maybe that was a bit of an exaggaration. So here's an actual picture of some drawers showing white molds lining along the edges. Those things are EVERYWHERE and on all my furnitures.
The shape of the mod reminds me of a bloater. I.e., :
It looks me on and off a few days to wipe down everything. And even then, there are still molds in the hard to reach cracks. I also have to toss all my pillows, blankets, and sheets.