Weather
Average temperatures in (C) and rainfall.
Q: How are the winters in Hanoi? Are the houses/apartments generally well-insulated and heated during winter time?
A: Winters don't get too cold usually, though with global climate change, you never know. You should bring some warm clothes with you, especially if you plan to vacation in colder regions of the world. As for insulation of houses/apartments, it depends on the place. But most places have air conditioners that you can change to heat mode, which are really effective in each room.
Q: I've been reading that the humidity ruins quite a number of paper prints and photographs, so I'm thinking of not bringing my framed photos along. What would you recommend?
A: Yes, the humidity can affect some paintings, but this is very much on an individual basis. Some have no problems with prints, but others have issues. Be prepared for serious heat and humidity in July/August when you arrive, and know that July/August is probably as humid and hot as it gets. There is also something that is called Moldy March, when is starts to heat up, but is still cold at night. Things can go moldy quite quickly. Most teachers use dehumidifiers throughout their homes (for a two bedroom apartment, three dehumidifiers are recommended).
Q: How do down comforters and wool clothing fare in the humidity during summer time? Should I not bring these at all?
A: They'll come in handy, as it usually gets cold for a little time, but mold does exist in a lot of houses. Dehumidifiers help. Also, you can purchase little moisture trappers to put in closets that will work in addition to dehumidifiers.
Q: How bad can the air quality get?
A: As mentioned in the "Lifestyle" section, air quality can get quite bad and has been getting worse in recent years. It is usually worst during fall and winter, though not as bad as some Chinese or Indian cities. You might want to bring an air purifier if you have one, though they can also be easily purchased here. If you want to check the air quality index (AQI), you can download the IQAir AirVisual app or go to aqicn.org/city/vietnam/hanoi.