And yet, their air pollution level during winter months is so bad that local government issues public alerts to encourage people to stay indoors. Every winter there are days when air is in top 10 most polluted areas around the globe.

My Polish coworkers say that's due to the senior citizens stuck in a Soviet occupation mindset, and they're doing things like burning plastic trash to heat their homes.

I really enjoyed Warsaw in December, the air seemed fine to me.

True. But this problem is fixable individually with a smog mask outdoors and air purifier indooes. Systemic issues in other countries are rarely so easy to work around.