From:	David Chock <dchock@ford.com>

To:	'blais.gary@epamail.epa.gov' <blais.gary@epamail.e...

Date:	10/14/96 11:18am

Subject:	Options for Designating PM-fine Areas

Comments on Options for Designating PM-fine Areas (October 14, 1996) -- =

David Chock

When the CAAA was consummated, there was no anticipation of a NAAQS that = had no federal reference method of measurement at the time of its = introduction. The present situation is, in a sense, self-inflicted. We = may be getting ahead of ourselves. Let me comment on the options.

The Ratio Method should not be employed for the 24-h standard because = the precision of the ratio deteriorates as we move toward the extreme = values. For the annual means, it may be OK, but then the ratios must be = locally based. But then we have no data to establish the local ratios. =

In conclusion, we cannot even use this method in a sensible manner. We = should avoid inventing data at all cost.

The Unclassifiable Method is the most logical and sensible from the = scientific and legal perspective. If we have no data, then we cannot = designate. In the Pros description, the first reason is not valid = because it implies some kind of a delay tactic on the part of EPA. But = how can it be if there are no data. A delay tactic may be suspect only = if EPA procrastinate in the introduction of the federal reference = method, etc. It is incumbent upon the EPA to introduce a scientifically = valid reference method and to install monitors expeditiously so that = meaningful designations are possible. In the Cons description, it is = not valid to say that somehow this approach ignores public health = problems. How can it be if we don't even know what the levels are? The = second statement is not valid either if EPA is to introduce the = reference method and to install monitors expeditiously. The =

"inconsistency" implied in the third statement is temporary and must be = anticipated and accepted.

The One-year Method is also inconsistent with the current three-year = practice and risk the lack of stability in the data. Why can't we just = do it right from the very beginning. =20

The AOI Method is not well defined here. There have been many = discussions on how to handle the AOV and AOI designations. But again, = if there are no data, how can we even start to talk about them. In the = last statement in the Cons description, the word "extending" implies = that AOIs must include AOVs. That is not how we interpret them anymore.

The Modeling and Monitoring Method is even more risky than some of the = methods described earlier. There is no PM2.5 model that has been tested = or evaluated. This fact is sufficient to kill this method.

Integration in designation has never been contemplated to date. That = may require the introduction of a new NAAQS and is probably impractical.

The bottom line is that we should do the designation responsibly and = credibly. This need automatically precludes designation without actual = data. Accordingly, the only sensible approach is to use the =

"Unclassifiable" designation until three years of PM2.5 data become = available.

CC:	'sanders.dave@epamail.epa.gov' <sanders.dave@epama...