Originally Posted by
TransitBiker
Raising engine efficiency and emissions standards for everything from that kerosene burner in the street vendor's food cart to mining trucks and locomotives and boilers/furnaces could make a drastic drop in noxious pollutants.
That's essentially what the WHO is saying. Reduce at the source, not at the end user.
Originally Posted by
noglider
[MENTION=324342]erig007[/MENTION], why do you suppose the air is so full of carbon inside the subway tunnels? Maybe it's brake dust? I do notice a sooty layer on everything. The train motors are electric, so they're not spewing soot. Other factors are that the tunnels are below the ground, so gravity brings dirt in. There are too few methods for the dirt to leave, and ventilation is insufficient to clear it.
I think [MENTION=112025]wolfchild[/MENTION] is right. Best not to worry about it unless you know it's a problem. And if it is a problem for you, I think the only solution is to move to a much cleaner place.
35 years ago I read that the benefit of exercising outside outweighs the detriments of air pollution. Of course, this can't be true in all places, but I suspect I'm healthier than lots of other New Yorkers.
The carbon could be coming from a number of different sources. Carbon black at the surface is oxidized quickly to carbon dioxide...you don't see large drifts of tire dust along the roadways...but that is largely due to sunlight and oxygen. But without sunlight, the reaction could be much slower.
And the tunnels in the subway are basically air pumps. The trains are the plunger. They could easily draw air from the surface that is ladened with tire dust, brake dust, dirt and other dark materials. Once out of the sun, the oxidation reactions slow down. The trains themselves have brakes, as you've pointed out, which could contribute. But the rails and the wheels also wear and that dust is going to appear black as well. Just because it is black doesn't mean it is carbon.