Expect more dire warnings in the months to come regarding air pollution, and expect to hear more exhortations not to drive. Unlike global warming, this is actually a man-made event in the offing in the Portland metropolitan area, as the next stages of the light rail construction that voters twice declined gets underway. The "planners" know better than the voters, and so they came up with some nifty work-arounds that allow them to build more stuff that we don't want.
Construction has begun along the I-205 freeway, which unfortunately means that traffic lanes are being reduced. Ditto for downtown Portland. The result, of course, will be increased traffic congestion along these routes, which means that more vehicles will be subjected to low speed or stop-and-go scenarios. Just what the "planners" want to see. After all, vehicles that travel at normal speeds emit far less pollutants into the air, and so by creating these bottlenecks, the "planners" can "encourage" you to drive less because driving is going to be causing increased pollution. They won't bother to mention that its not your fault - it's theirs.