Chris,
You are quite right about that. It is also proven that sunlight is a major cause of skin aging. She uses any possible methods/means that she could think of to avoid that. At Yunnam, it was OK, since we were at altitude of +1300m most of the time, temperature was around 26 degree C or something even under strong sun/clear sky. At the end of this trip when we returned to Shenzhen where the air is polluted/temperature is high and humid, after getting off the train, we had to ride a few km to a bus station where we could get transportation back to Hong Kong, she got sick/felt difficult to breath/vomit, shown signs of heat stroke. Luckily she got better after resting sometime in an air-conditioned koisk. That sure taught her and me a good lesson. She still does covering-up now but cautiously.
I see you are from Switzerland, I am planning a tandem trip to Germany. Can I ask questions about train ride with a tandem in Germany? Should I start a new post here?