But some lines are better than others and while the more modern lines have lovely cooled air circulating, some of the older lines feel like the second circle of hell. READ ALSO The strange rules of the Metro you should know aboutThe are three types of ventilation on the lines - natural ventilation via grates at street level, mechanical ventilation with what are essentially fans and ventilation with chilled air. The coveted chilled air is circulated on just four lines 1,2,5 and 9, which generally cross the city going east to west. This is generally bad news for people who live in the southern part of the city, which is only served by fan cooled or not cooled lines. The modern tram system is entirely air conditioned apart from the T1, which will be cooled from 2022.

Source: The Local July 22, 2019 06:56 UTC