According to the World Health Organization, approximately 80 percent of people living in cities breath unclean air. Cities in developing nations are particularly vulnerable because of things like inefficient fuel sources used for cooking and automobile pollution due to overcrowding.
In Africa, air pollution is more deadly than malnutrition, unclean water or unsafe sanitation, killing 700,000 people every year. Cities across China and India have been facing pollution epidemics for the past two decades.
Today's Seeker Daily video explores which cities around the world are the most polluted and what's being done to combat this deadly problem.
Daily Mail: Nearly HALF of Delhi's children suffer 'severe' lung problems due to air pollution
CNN: Nearly HALF of Delhi's children suffer 'severe' lung problems due to air pollution
The Guardian: Beijing raises 'red alert' threshold for air pollution warning