The pollution (and weather) has been worse in winter for as long as I’ve been here. This year it has reached unprecedented levels, but the general trend has remained, so I expect it to improve as we exit the winter. There are some precautions you can take which will make a big difference on how much the pollution impacts you. It’s definitely a concern, but if you have air filters at home I think you’ll be fine. If you read the post that I linked to a few sentences ago you’ll see a link in that post to a doctor in Beijing who compared the pollution there being not nearly as harmful as most people believe it to be.