In Mercer's 2015 annual quality-of-living survey, New Delhi ranks at number 154 out of 230 cities due to bad air quality and pollution.[45][46] The World Health Organization ranked New Delhi as the world's worst polluted city in 2014 among about 1,600 cities the organisation tracked around the world.[47][48][49][6] In 2016, United States Environmental Protection Agency listed New Delhi as the most polluted city on Earth[51][52] and IQAir listed New Delhi as the world's most polluted capital city for the second straight year in year 2019.[53]