The air is terrible in Seoul right now, I can't see the mountain 7km from my office today.
I just checked my app and Beijing, Shenzen and Shanghai look cleaner than normal, probably less than normal activity. Xian is really bad today (it has a lot of industrial facilities that cannot shut down due to massive costs and global demand), but Wuhan/Heibei area is really really clean which means they are still up to nothing much.
In anycase the amount of sulfur 1 medium coal plant produces is going to dwarf the amount of sulfur produced by burning thousands of bodies.
China is pretty good at covering stuff up, but I've got a lot of friends and coworkers who live in China and they would probably mention piles of bodies. Wuhan isn't some back water place. It has infrastructure that puts most of the west to shame.
Besides hundreds of people are still being evacuated and none of them are mentioning anything about a huge cover up when theybare safe and sound far away from there.