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In the sense that they don't emit plastic particles, sure. But trains absolutely do create metal particle air pollution.

I think it would be an interesting comparison, given how often our local light rail trains operate nearly empty. If it has less than about 20 people per train car it is toting around more weight per passenger than a private vehicle with just the driver.

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adrianN 13 hours ago | parent | next [-]

Steel dust has the nice property of turning into mostly harmless metal oxides rather quickly.

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rootusrootus 12 hours ago | parent [-]

Iron isn’t the only metal in those wheels, some are more poisonous.

	▲	adrianN 10 hours ago \| parent [-]
		Stainless is mostly iron and chromium, sometimes nickel. Some oxidation states of chromium are indeed toxic, but the most stable form is chromium(III), which is harmless enough that you can buy it as a supplement. Nickel also occurs naturally in soil and many foods and is not accumulating in the body. The kidneys can remove it. Only large doses are problematic.

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rootusrootus 4 hours ago | parent | prev [-]

Huh. Downvoted for mentioning a fact that has been studied in depth and is uncontroversial. You guys crack me up.