LOS ANGELES (CBS) — When it comes to air quality, not all mass transit systems in Los Angeles are created equal.

A new study released by USC on Thursday shows commuters on the Red Line subway may be exposed to up to twice as many hazardous air pollutants as commuters on the Gold Line light rail system.

Professor Constantinos Sioutas told KNX 1070 the study sought to duplicate a typical passenger experience on both transit systems.

“We actually have devices that classify particles into different size ranges,” Sioutas said. “We put the samplers into a small carry-on, we ride the trains of the Red and the Gold lines and we collect sufficient samples for analysis.”

But despite both rails utilizing electric delivery systems, researchers found a higher concentration of particulate matter along the Red Line — a finding Sioutas attributed to the amount of dust produced when a train brakes as it pulls into the enclosed subway environment.

“If you think about it, most of the rail is actually iron and metal alloy, maybe a little chromium in it,” said Sioutas. “With braking and all of these high-temperature processes, it’s conceivable that some of this material is released into the air.”

While the findings may have been unexpected, they still pale in comparison to the levels of particulate matter found on our city’s freeways.

“The air inside the trains is actually cleaner than almost any other urban site that we have in Los Angeles,” said Sioutas.

The level of pollution along either rail system is at levels that are comparable or even lower than what one would find in the city’s urban environments, Sioutas added.

owever, the Metro system’s levels of these air pollutants, some of which are known carcinogens, pale in comparison to the levels of particulate matter that bombard commuters stuck in traffic on the freeways.


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