Pollution Masks

Not exactly useful, I got more pollution in the Victoria Line than riding 11 miles to Clerkenwell.

If you want to find out how, pinch your nose when you finished your journey in the Victoria Line and you´ll notice you have black mucus from the dust.

+1 Ed - spot on.

Riding to work - clean snot.
Northern line to work - black snot.

There's my research. Imperial college can kiss my arse.