U.S. President Donald Trump’s description of India as a filthy place with polluted air has unleashed calls on social media for urgent clean-up action, particularly over New Delhi, the world’s most polluted capital. Defending the clean air in the United States, Trump made the comment during his final debate on Thursday with Democratic rival Joe Biden ahead of the Nov. 3 presidential election, saying “Look at India. It’s filthy. The air is filthy.”