NEW DELHI, October 26 (Reuters): New Delhi's appalling air quality turned a lot worse over the weekend as Hindus in India's capital burned effigies of the mythological demon king Ravana and lit firecrackers to celebrate the triumph of good over evil during the Dussehra festival. As pollution spiked on Monday morning, India Gate - a monument near the Prime Minister Narendra Modi's office - was blanketed in smog, and the mega-city's 20 million people breathed in &