The Indian Express: "Public transport and parking in residential areas were made free to encourage people to use public transport. According to the government, the steps were successful and helped cut pollution significantly.
2015 was only the third time since 1997 that the city had to implement emergency measures.
Mexico City too made public transport free when air quality dipped last year.
When it declares an air emergency, Mexico City bans a fifth of private cars from roads on every day of the week. It also offers free rides on buses and trains."