What are the most polluted cities on Earth?
Air pollution is a global problem. The United Nations has deemed air pollution as "the world's single greatest environmental health risk." Every month there is a story from a new country and a new city dealing with haze, smog and dangerous air. With the historic Paris Climate change agreement ratified, O2 Canada examines the most polluted cities on earth. Here's the list: Travellers beware and be sure to take an O2 Mask with you on your journey!