1. It warned people against being exposed to the sun for extended periods as hot weather increased the risk of heat strokes.
2. When Europe was primarily an agricultural society, most of the population was constantly exposed to the sun while working in the fields.
3. Skin produces vitamin D when directly exposed to the sun, but this is usually not enough.
4. When the weather is fine and the sun shines brightly, the seeds are scattered on bamboo mats and exposed to the sun for a week.