Pollution and emissions are two parts of a worldwide problem, but some cities have to contend with worse conditions than others.
Beijing, China, is well known for its smog situation, but it's one thing to hear about it and another thing entirely to see it. China has made progress toward clearing its air, but current levels of a particle called PM 2.5 are still at twice the limit recommended by the World Health Organization. Twitter user Chas Pope recently filmed a time-lapse video showing how smog fills the city over the course of 20 minutes each morning.
It starts out fairly clear, but soon the smog is so thick that visibility is lowered. Can you imagine breathing all that in?
(via Popular Mechanics)