With recent worries about global warming, holes in the ozone layer, and skin cancer, many people are slathering up on sun block when they go outside for any length of time.

• 近来，由于对全球变暖、臭氧层空洞以及皮肤癌的担心，许多人外出之时无论外出时间长短都要涂抹防晒霜。