When going thru baggage claim there are signs for the Air China premium lounge. In the far right corner of baggage claim, there’s a lounge that is basically only private showers/toilets, and very nice ones at that. See pictures. The shot in the shower room is a panorama btw. They also have basic beverages and a small sitting area. Very pleasant surprise. No waiting at 630am, there was only one other person, I saw exiting as I arrived.