There is one thing worse than the frequencies of the Metro at rush hour, the very polluted air we breathe when we travel inside
It is highly likely that the 4.8 million passengers use the London Underground on a daily basis do not know where they are going. The Financial Times has just published an investigation into the air quality in the London Underground cars and the conclusions are quite alarming: in some areas of the network the pollution levels were up to 10 times higher than the levels recommended by the WHO .
This is in addition to a recent scientific study that has concluded that the air in the London Underground cars is up to 18 times worse than the air on the surface. One would think that, after all, London is the oldest underground in the world and it is logical that it has more problems than the others.
But, far from that, the British capital is not alone. Air quality is a problem in every major city on the planet. Also underground.
The metro in Spain
A few months ago, chemists Carlos Pérez Olozaga and Jose Antonio Meoqui analyzed the air quality indices of the Madrid Metro. According to the researchers, the preliminary data showed increases of up to five times in the air pollution of lines 1 and 10 of the capital (with respect to the exterior).
Another IDAEA team from the Higher Council for Scientific Research coordinated by Teresa Moreno analyzed the air quality of Barcelona's urban transport and found that pollution on the metro is greater than on buses, the street or the tram. However, the same authors insisted that, in general, "the air in the metro has higher levels of air pollution than trams or walking on the street, but it is slightly lower than on buses." This is something that is repeated in many cities around the world such as Hong Kong, Mexico City, Istanbul or Santiago de Chile.
If you look, they are macrocities and that already gives us some clues. Olozaga and Meoqui had previously studied the Bilbao and San Sebastián subways without finding divergences between the exterior and interior of the network. Age, depth, and size seem to be key features in understanding why undergrounds are so polluted.
A long list of things to do
It cannot be said to be a surprise. In 2012, and while studying the Barcelona Metro, the CSIC already warned that "the air in the metro network contains polluting elements from the outside environment, in addition to others resulting from the abrasion of the train wheels in contact with the rails, cleaning or maintenance work. "
This required careful study of the problem and action. Measures that, in general, have not been taken because the financial crisis slowed down large investments (+). However, now that mobility is a key issue again, it seems a good time to bring this issue to the center of the debate.
Image | Karol Kaczorek