Delhi is the most polluted city in the world right now, according to an air quality index, or AQI, measured by Switzerland's IQAir. Pakistan's Lahore comes next.
All 50 states were ranked by EPA to determine which state is most polluted in the US. All 50 states were ranked by EPA to determine which state is most polluted in the US.
EPA Administrator Michael Regan is expected to continue touring several poor communities within Puerto Rico to learn how pollution has affected them. This is all part of a U.S. initiative called "Journey to Justice."