The worst air pollution in the world
-- Ecuador was the most improved country when it came to air quality; Russia and Iraq had the biggest drops in the effects of their air on human health.
-- The worst countries for air pollution are clustered in South Asia and Central Africa.
You can delve deeper into the study and explore an interactive map of the findings using the Yale University Environmental Performance Index.
-- Emily Alpert in Los Angeles
Photo: India Gate war memorial is seen through haze in New Delhi. Credit: Saurabh Das / Associated Press