Paris and much of northern France have seen dangerously high pollution levels this week, forcing authorities to offer free public transportation to Parisians for the next few days. Smog levels are similarly elevated in London, where air quality index readings on Friday were higher than the smog-plagued Chinese cities of Shanghai and Beijing, according to the nonprofit group Clean Air in London. On Friday, Paris Air Quality Index (AQI) readings hovered around 185, putting it on par with Beijing, one of the worlds most polluted cities.