I've seen independent research on inside air quality, and it agrees with the claims made in the article. Similarly, I've seen research that shows that different brands of air filters are able to provide different levels of clean air. The better (and more expensive) filters (like BlueAir) are able to filter down to, I believe, 0.1 microns, while cheaper models (like Honeywell) can do .3 microns; the US Embassy readings that are the object of so much debate measure particles 2.5 microns and smaller, which are those linked to cancer, heart disease, etc.
Similarly, different brands of purifiers are able to cleanse the air at different rates; the faster an air filter can clean the air, the cleaner the air in the room will be. For foreign brands of air purifiers, you can check look up the CADR (clean air distribution rate) online.
The question that no one seems able to answer is what is the "optimal" amount of scrubbing that air needs to keep us all from getting lung cancer and dying young. Given how disgusting Beijing's air has been, I'm like to believe that the more scrubbing the air can get, the better.
A month after arriving in Beijing we bought a 1,000RMB Midea HEPA filter, which immediately stopped me from waking up with a runny nose and a cough each morning. We've also bought a number of plants. owever, we've also ordered a BlueAir and will probably pick up a Honeywell, too, since they're only around 800RMB on taobao.
My wife has just gotten a very good job here in Beijing, but I very much want us to get out of the city. The air makes it unlivable. I don't think either of us needs to be here so badly that we'd be willing to give up five or six years of life, which is a legitimate worst-case scenario.