from the environmental law handbook:
The centerpiece of the clean air act has been the national ambient air quality standard (NAAQS) program. The NAAQS addresses pervasive pollution that endangers public health and welfare, and standards have been established for six pollutants: sulfur dioxide (SO2), nitrogen dioxide (NO2), particulate matter (PM), carbon monoxide (CO), ozone (O3), and lead (Pb). For each of these pollutants, NAAQS are set at levels designed to protect public health with an adequate margin of safety...and to promote public welfare..."
Chapter 2.1 then tells how EPA monitors air levels. If, in your county (or otherwise denoted EPA region) your air quality is not suffering, you will have different levels of allowable emissions. (hence Cali being all strict). This is not just for motor vehicles, but for industry, and VOCs (volatile organic compound) from gas stations you may notice have bellows or not (the rubber things on the gas pump), depending on the region where you are. In my state, near UConn (w00+) in Mansfield there are gas stations with bellows, but right down the road, there aren't any. In between is an EPA boundary line, and one area has more VOCs and other air pollutants than the other.
I just didn't think that any emissions levels would be allowed to backslide, or what? I mean, that if CT attains its allowable levels and has enough room to get rid of emmission stations, why would the state not simply reduce the allowable levels to maintain air quality? I've not read anything that the air quality is improving, anyway. Maybe the emissions stations arent closed and this entire post is moot. heh.