The city of London, which now imposes a xACxA35 fee on cars entering the center city, has enjoyed an unexpectedly rapid fall in air pollution. Particulates (the ultra-fine soot that issues from car and truck tailpipes), carbon monoxide, and nitrous oxide are all down by 12 to 20 percent since the congestion fee was imposed. The fee, originally intended to reduce the crippling traffic congestion in downtown London, may be lightening the burden on Londoners’ lungs as well as their streets.