I was in a taxi in the west end a few days back when we came upon a water-cannon truck at a red light. Nice of the driver not to turn off the cannon at the red light and soak all the cars within range.
It just seems like such a ridiculous idea. Hard to imagine there is any hard science to back it up on a scale that would make any significant difference. I wonder how harmful the atomized dust retardants are to one`s lungs.
Why not put up some giant fans and see if we can just blow the pollution away.
Actually water cannons for dust supression at construction sites are normal in civilized countries where they are not actively attempting to kill off the elderly population via cancer, heart disease and emphyzema to circumvent a population time bomb that is coming down the pipeline as a consequence of the one-child policy.
However I believe this only has an effect on relatively coarse dust rather than car emissions