New Delhi, Jan. 8 -- Anyone who has lived through a North Indian winter knows the routine. The heater comes on, the room warms up beautifully. and within an hour your skin feels like it's been quietly sandblasted. Hands dry out first, then your face, and by day three, even your lips stage a protest. Most people blame the cold air outside, but in reality, it's the heater doing exactly what it's designed to do, which is pulling moisture out of the room faster than you can replace it.

The trick isn't buying a new heater or slathering on heavier creams. The real fix is correcting the micro-climate inside the room. And the simplest, most effective hack, the one technicians mention casually and grandparents somehow knew without manuals, is pla...