"The World Health Organization says air pollution in many of the world's cities is breaching its guidelines. Its survey of 1,600 cities in 91 countries revealed that nearly 90% of people in urban centres breathe air that fails to meet levels deemed safe.

The WHO says that about half of the world's urban population is exposed to pollution at least 2.5 times higher than it recommends.

Air quality was poorest in Asia, followed by South America and Africa."

Rebecca Morelle reports for BBC News May 7, 2014. [2]

SEE ALSO:

"Delhi Most Polluted City in the World: WHO" (Press Trust of India) [3]