I have sinus issues as well, and actually Beijing in January is not a problem for that (actually, it's helpful--I never seem to have sinus flareups in dead of winter). It is very dry and a good facial moisturizer and body lotion (yes, even for a guy) is good to put on at least once a day or at night. My standard Beijing January outdoor weather gear:

1) Long underwear under pants. Pants should be fairly thick or wool blend, or heavy athletic sweatpants. No jeans!

2) Turtleneck or similar, usually not with thermal underwear. Heavy cotton blend or wool if you prefer.

3) Fleece over that (may not be needed if you instead use thermals under your shirt).

4) Heavy coat over that. If coat has a built-in hood, no need for additional hat or cap unless you are balding.

5) Reasonably thick wool-blend socks. Or use thin cotton pair then thin wool pair over that. Socks that come up at least calf-high. Then any sort of closed in-shoe or boot, in Beijing athletic shoes are OK for casual sightseeing even in winter. You don't need fur-lined boots or anything like that!

6) Long Scarf or muffler--wool or fluffy acylic. You can wrap lower part of your face in this if the wind is biting (not always necessary).

7) Gloves, lined. They don't need to be ski gloves, but something leather or closed-in, with thermal lining---no open-weave knitties.

8) No exposed metal, this includes ear and nose piercings. They will freeze to your skin, so take things like this off.

Old Norwegian proverb: There's no such thing as bad weather, just bad clothes. If you are properly geared up, even tropical-living people can get through a few days in a Beijing January. Heck, my Fiji friend and I (from Florida) survived Ice Festival in January in Harbin--which is a couple of magnitudes colder than Beijing and which needs even heavier/better winter gear. If it's anything like today, the sky will be blue, cloudless, and lovely.