Traffic jam air cleaners

I just came up with an idea to decrease the problem of traffic air pollution. Much of the pollution comes from cars, moving slowly in traffic jams. So why not place some pipes with holes in (or maybe even above) heavily congested streets by intersections so they could suck up the polluted air to a cleaning station and spew it out cleaned? This could avoid the yellow cloud, that is often following the parts of streets with heavy traffic and pollution. On the other way, we already have catalytic converters so pollution is a lot smaller than a decade ago. Despite that, such invention should be very useful in developing countries e.g. China, where air pollution is still a problem.