From:	<Poirot_Richard/vt_state_dec_airpoll@qtm.anr.state.vt.us>

To:	RTP3.RTMU540(SANDERS-DAVE)

Date:	12/2/96 1:23pm

Subject:	feasibility of attainment issue paper -Forwarded

Comments on 'feasibility of ozone attainment' issue paper

from Rich Poirot, VT DEC

This potential 'non-feasibility' seems a very important issue. Surely

the motivation will not be great to implement costly strategies which

are doomed to failure. A related issue, pending possible retention of

both 1-hr. and 8-hr. standards, is that in some areas, strategies to

attain A may conflict with strategies to attain B (this issue needs

further clarification).

Some thoughts:

1. The assumption of feasibility is logical and has historical

precedent, but does it have a legal basis? (someone must know this?).

2. Concerns about 'non-feasibility' may be partially offset by the

apparent 'lack-of-threshold' for ozone health effects. A standard at any

level (above 'natural background') will be set 'as if' a threshold

exists (ie based on a faulty assumption). In this case, any progress

toward reducing the magnitude and/or spatial extent of 8 hour exposures

has implied health benefits - regardless of an area's current

concentration and its relation to the standard.

3. The feasibility of, and associated control requirements for,

attaining (or making progress toward) the standard need to be

co-evaluated. A 'low standard' may place much of the East in NA status

(and may result in non-feasibility in some areas). Depending on what's

required, where and when (AOV, AOI, SIPs, etc.), this might tend to

inefficiently allocate control resources. On the other hand, if we cop

out on AOI, then a low standard might have the beneficial effect of

transforming a transport problem into a local problem. A 'high' standard

might tend to more efficiently allocate control resources, particularly

in the East, where high chronic 8-hr. levels (without associated high

peaks) tend to occur in the (largely uncontrolled NOx and PM-relevant)

Ohio River Valley. (See

http://capita.wustl.edu/OTAG/Reports/areaov/OTAGAOV.HTM for some

informative graphic images depicting areas with high 1-hr. and high

8-hr. concentrations). If the standard is too high, and if we also choke

on the AOI concept, some of the most important emissions areas and

source categories contributing to the most pollution problems over the

largest range of downwind areas, may remain uncontrolled (ie. the status

quo).

4. What is (are) the 'natural background' ozone concentration(s) in the

US? The figure of '> 60 ppb' is cited for 'clean areas' in the US. To

what extent, if any, are these 'clean, > 60 ppb levels' influenced by

anthropogenic emissions? How frequently do they occur (what's the 3rd

high 3-year average)? How does the timing of these clean peaks coincide

with the anthropogenic peaks? Perhaps clean-site peaks tend to occur in

Spring under conditions of max stratospheric intrusion? If they occur in

mid-Summer, then an anthropogenic influence (presumably reducible

through emission controls) would seem likely. What is the spatial

distribution of 'natural background'?

5. The modeled demonstration of non-feasibility demonstrates that a

VOC-only strategy is prohibitively expensive in 2 VOC-limited areas.

This (VOC-limited assumption) is not necessarily representative of all

8-hr (or 1-hr.) non-attainment areas, and a VOC-only control approach is

likely to be especially inefficient at reducing background transport

contributions to any areas in the East (California may be different).

The OTAG UAM-V model results (for what they're worth), and several OTAG

Air Quality Analysis results clearly suggest the advisability of NOx

controls for reducing ozone levels throughout the East. Relative to a

1-hr. peak, an 8-hr. peak is necessarily more heavily influenced by

transport in most cases, and as distance increases, NOx-sensitivity

increases. Therefore, I suggest that the modeled demonstration of

non-feasibility is primarily a demonstration of non-feasibility of

attainment through local VOC controls. What if NOx emissions were

reduced nationally up to the (cited VOC control) cost of $30,000/ ton?

6. Above comments notwithstanding, I agree with the "Recommendations" in

this issue paper. An additional useful exercise, based on historical

monitoring data, would be to compare the temporal (and spatial)

relationships between 1-hr. and 8-hr. max values. I suspect that in some

areas the dates of peak 1 and 8-hr. concentrations may not coincide well

- ie. different kinds of episodes will affect attainment status (and

will be selected for modeling or weight-of-evidence attainment

demonstrations).

Rich

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