How do i safely remove a black film from my white wall paper?

There is a dark smoke like film all over my apartment, the walls the cupboards, even the carpet is becoming discolored. No one in the house smokes though. Any suggestions on what it might be and/or how I can safely remove it without damaging the wallpaper or the carpet?|||Try making a bucket of mr clean. If you burn candles a black film will cover your walls. I've cleaned a lot of rental houses and it's a common problem.|||I would try windex... what ever film should come right off. And it shouldnt strip the walpaper off the wall....