Highbeam is correct. Having been through hundreds of meetings with EPA and other regulators in the past 15 years, everything is data driven. However Highbeam, keep in mind that imposed standards must also be cost effective. An example might be, does a change in a standard from 4.5 gr/hr to 4.2 gr/hr have a health dollars benefit when compared to the increased cost for engineering and design and corresponding retail cost....not likely so there's little shot of getting it approved. But going from 4.5 to 2.0, now that opens a whole new list of possibilities.....and that much reduction in pm inventory can make a reduction of the standard of that magnitude much more likely.
It will always come done to money...
It will always come done to money...