India's western state of Gujarat has launched the world's first "cap and trading" program in an effort to combat particulate air pollution. The program is being launched in the city of Surat, where textile and dye factories are a major source of pollution. Under the program, the government will set a cap on emissions and allow the factories to trade permits among themselves to stay below the cap. The trading system is intended to incentivize factories to find new and inexpensive ways to reduce their emissions because they can sell any extra reductions to other factories. For the full story, see https://www.bbc.com/news/world-asia-india-48744163.