Commuting by metro? What you need to know about air quality

Key factors influencing metro air pollution will include station depth, date of construction, type of ventilation, types of brakes and wheels used on metros

 

Four more major Indian cities will soon have their own metro lines, the country’s government has announced. On the other side of the Himalayas, Shanghai is building its 14th subway line, set to open in 2020, adding 38.5 km and 32 stations to the world’s largest subway network. And New Yorkers can finally enjoy their Second Avenue Subway line after waiting for almost 100 years for it to arrive.

In Europe alone, commuters in more than 60 cities use rail subways. Internationally, more than 120 million people commute by them every day. We