Underground train riders are exposed to far more cancer-causing air pollution than is safe, recent research reveals.
In Los Angeles, levels of toxins on one of the city’s most heavily-trafficked lines are 10 times greater than what is deemed acceptable by the US government and international health organizations, a University of Southern California study found.
But even the busiest Los Angeles train lines see far fewer trains and commuters than other metropolitan areas like New York and London, where billions are in danger.
The study’s findings suggest that subway systems – and particularly subway cars – need to be better ventilated to prevent the accumulation of dangerous toxins.
The grind of train cars against tracks produces a fine, carcinogenic dust that that settles into the cars, elevating commuters’ lifetime risk of cancer 10 fold
Public transit is thought to reduce the green house gas emissions released into the environment by limiting the number of cars on the road.
The US Environmental Protection Agency (EPA) estimates that about 27 percent of total green house gas emissions come from the transportation industry and that the majority of that is created by cars and trucks on the road.
In addition to the USC study, Canadian research published last month concluded ‘expanding the current configuration of public transit in North American cities is unlikely to yield improvements in local air quality.’
Meanwhile, evidence suggests that continued use of current underground systems without improvements poses a serious risk to public health.
The grind of train cars against steel tracks creates a fine dust that is harmful to humans. The dust collects in underground tunnels and train cars, where there is insufficient ventilation to whisk it away.
Los Angeles ridership has been on the decline, falling 20 percent in the last year, according to statistics from this past summer.
Health risks of air pollution in underground trains
PAHs, or polycyclic aromatic hydrocarbons, are very fine air pollutants.
They are released by many industrial processes, including coal, oil trash and gasoline burning and steel-making.
The fine particles get into humans’ lungs and other internal organs.
There are more than 100 kinds of PAHs.
They are known to cause gastrointestinal, skin lung and bladder cancers in workers who are exposed to dangerous levels of the toxins.
But in cities like New York and London, underground trains are essential to the daily lives of millions of commuters, in addition to visitors.
Each year, 1.65 billion people ride New York City trains. In London, about 2.18 billion people use trains annually.
Steel train rails contains an element called chromium. When the metal is heated or subjected to friction – as it is as train cars run on the rails – a compound called hexavalent chromium is created.
Exposure to the compound is known to cause cancer.
Extremely fine air pollutants – called polycyclic aromatic hydrocarbons (PAHs) like hexavalent chromium – are particularly worrisome, as little can be done to protect us from coming into contact with them.
They can infiltrate and become imbedded in the lungs and other internal organs, where they wreak havoc on our health.
Hexavalent chromium is linked to nasal and sinus cancers, damage to the kidneys and liver, and irritation to the skin and eyes.
The more train cars grind against the steel tracks, the more toxic dust is produced, and the greater the risk of health conditions becomes for commuters.
In New York City, for example, there are more than 6,000 train cars in service.
The Los Angeles subway system requires that train car windows be kept closed at all times, but the new University of Southern California research found that that measure did not keep commuters safe.