UNITED ST ATES E N VI RON M E N T A L PR OTE C TION AGE NCY WASHING T O N D. C. 20460

OFFI CE OF THE A D M I N ISTR A T OR SCI E NCE A D VI SORY BO A RD Nove m b er 29, 2007

EPA-CASAC-08-003

Honorable S t ephen L. Johnson Adm i nistra tor U.S. Environm ental Protection Agency 1200 Pennsylvania Avenue, NW Washington, DC 20460

Subject: Clean Air S c ientif ic Advisory Comm ittee’s (CASAC) NO X & SO X Secondary NAAQS Re view Panel’s Consultation on EPA’s Draft Plan for Review of the Secondary NAAQ S for Nitrog en Di oxide and Sulfur Dioxide (Septem b er 2007 Draft)

Dear Adm i nistrator Johnson:

The Clean Air Scientific Advisory Co mm ittee (CASAC) NO X & SO X Se condary NAAQS Review Panel m e t on October 30, 2007 and has co m p leted its consultative review of EPA’s Draft Plan for Review of the Secondary N AAQS for Nitrogen Dioxide and Sulfur Dioxide (Septem b er 2007 Draft). A consultation is c onducted under the norm a l requirem e nts of the Federal Adv i sory Committee Act, w h ich inc l ude advance notice of the public m eeting in the Federal Register. The CASAC uses a consulta tion as a m echanism for individual technical experts to provide comments on the Agency’s dr aft plan for developing technical assessm ents as the basis of the review of the secondary NAAQS review for NO X and SO X . W r itten comments provided by the individual Panelists are attached to th is letter. As this is a consultation, we do not expect a form al response from the Agency.

We thank the Agency for the opportunity to provide advice early in the NAAQS review process, and look forward to the review of th e draft Integrated Science A ssessm ent in March 2008.

Sincerely,

/Signed/

Ar m i stead (Ted) Russell, Ph.D. Chair, CASAC NO X & SO X Secondary Review Panel

Attachments

Attach ment A: Roster of CASAC NO x & SO x Secondary NAAQS Review Panel Attach ment B: Com p ilatio n of In divid u a l Panel Member Comments on EPA’s D r aft Plan for Review of the Second ary NAAQS for Nitrogen Dioxide and Sulfur Dioxid e (Septem b er 2007 Draft)Attachment A: Roster of CASAC NO x & SO x Secondary NAAQS Review Panel



### U.S. Environmental Protection Agency Clean Air Scientific Advisory Committee NO x 

### & SO x 

### Secondary NAAQS Review Panel

CASAC MEMBERS

Dr. Armistead (Ted) Russell (Chair) , Professor, Department of Civil and Environmental Engineering, Georgia In stitute of Technology, Atlanta, GA Dr. Ellis B. Cowling , Emeritus Professor, Colleges of Natural Resources and Agriculture and Life Sciences, North Carolin a State University, Raleigh, NC Dr. Douglas Crawford-Brown , Professor and Director, De partment of Environmental Sciences and Engineering, Carolina Envir onmental Program, University of North Carolina at Chapel H ill, Chapel Hill, NC Dr. Donna Kenski, Director, Lake Michigan Air Dire ctors Consortium, Rosemont, IL

PANEL MEMBERS

Dr. Praveen Amar , Director, Science and Policy, NESCAUM, Boston, MA Dr. Andrzej Bytnerowicz , Senior Scientist, Pacific S outhwest Research Station, USDA Forest Service, Riverside, CA Ms. Lauraine Chestnut , Managing Economist, Stratus Consulting Inc., Boulder, CO Dr. Charles T. Driscoll, Jr. , Professor, Environmental Systems Engineering, College of Engineering and Computer Science, Syracuse University, Syracuse, NY Dr. Paul J. Hanson , Distinguished R&D Staff Memb er, Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN Dr. Rudolf Husar , Professor and Director, Mechanic al Engineering, Engineering and Applied Science, Center for Air Pollu tion Impact & Trend Analysis (CAPITA), Washington University, St. Louis, MO Dr. Dale Johnson , Professor, Department of Envi ronmental and Resource Sciences, College of Agriculture, Un iversity of Nevada, Reno, NV Dr. Naresh Kumar , Senior Program Manager, Envi ronment Division, Electric Power Research Institute, Palo Alto, CA Dr. Myron Mitchell , Distinguished Professor and Dir ector, College of Environmental and Forestry, Council on Hydr ologic Systems Science, Stat e University of New York, Syracuse, NY Mr. Richard L. Poirot , Environmental Analyst, Ai r Pollution Control Division, Department of Environmental Conservati on, Vermont Agency of Natural Resources, Waterbury, VT Mr. David J. Shaw , Director, Division of Air Resources , New York State Department of Environmental Conservation, Albany, NY Dr. Kathleen Weathers , Senior Scientist, Institute of Ecosystem Studies, Millbrook, NY

SCIENCE ADVISORY BOARD STAFF Ms. Kyndall Barry , Designated Federal Officer, 1200 Pennsylvania Avenue, NW 1400F, Washington, DC, Phone : 202-343-9868, Fax: 202-233-0643, (barry.kyndall@epa.gov)Attachm e nt B: Comp ilation of Indi vidual Panel Mem b er Comments on EPA’s Draft Plan for Review of the Secondary NAAQS for Nitrogen Dioxide and Sulfur Dioxide (Septem b er 2007 Draft)

Co mm ents from CAS A C NO X & SO X Secondary NAAQS Review Panel on EPA’s Draft Plan for Review of the Secondary N AAQS for Nitrogen Dioxide and Sulfur Dioxide (Septem b er 2007 Draft)

Comm ents from Dr. Praveen Am ar

.................................................................................... 4 Comm ents from Dr. Andrzej Bytnerowicz

......................................................................... 6 Comm ents from Ms. La uraine Chestnut

............................................................................. 9 Comm ents from Dr. Ellis Cowling

................................................................................... 11 Comm ents from Dr. Dougl as Crawford Brown

................................................................ 21 Comm ents from Dr. Charles Dr iscoll

............................................................................... 23 Comm ents from Dr. Paul Hanson

..................................................................................... 25 Comm ents from Dr. Rudolf Husar

.................................................................................... 27 Comm ents from Dr. Dale Johnson

.................................................................................... 28 Comm ents from Dr. Donna Kenski

.................................................................................. 32 Comm ents from Dr. Myron Mitchell

................................................................................ 36 Comm ents from Mr. Richard Poiro t

................................................................................. 36 Comm ents from Mr. Da vid Shaw

..................................................................................... 43 Comm ents from Dr. Kathleen W eathers

........................................................................... 44

3Comm ents from Dr. Praveen Am ar

EPA’s Draft plan is a commendable effort on th e part of EPA staff to present in a short docum ent the key policy -relevant iss u es, and the n describ e h o w it will as sess is sues related to (1) scien ce, (2) risk-exposure, and (3) policy, as they inform the com p lex process of establishing secondary standards for both NO 2 and SO 2

.
The draft plan, to its credit, recognizes that we have arrived at the cu rrent state of affairs in establishing separate NAAQS for SO 2 and NO 2 in an ad hoc m a nner by historically considering “one pollutant” or “one atm o sphe ric or ecolog i cal issu e” at a tim e. The goal of considering the two pollutant s in a joint “integrated” m a nner under the current review process, because of the “science-entanglem ent” of both the atmospheric processes and ecological effects of the two pollutants, is worthwhile, but not without its own set of policy-related problem s. For exam ple, such a “m ulti-pollutan t /one atm o sphere/d iver se and variable ecosystem s” approach can easil y lead to a policy-situation where one can

not m a ke “som e” necess a ry policy d ecis i ons unl ess one is re ady to m a ke “all” decisions. For example, we should be careful that such an “integrated” appro ach does not lead to not setting a nitrogen-based standard in the c ontext of eutrophication of water bodies in certain regio n s of the US in the ab sen ce of comp lete inf o rm ation re lating to sulf ur-bas ed im pacts.

The Draf t Plan (page 1

- 1 3 ) notes that the ro le of ammonia “will be con s ide r ed,” while it is “not the focus of this review .” It goes on to state that “a detailed discuss (sic) of these processes is included in the PM review.” I thi nk it is important that amm o nia also be th e focus of this review in the cont ext of “total nitrogen and to tal sulfur”, and not just the oxidized f o r m s of nitrogen and sulf ur. This m eans that its em issions a t abo u t f i ve m illion tons per year in the US (there is high level of unc erta inty a sso ciated with this estim a te)

, location of its m a jor sources in the US, its role in long-range atm o spheric transport and then deposition as amm o nium sulfate and ammonium nitrate, its ch em istry in the

atm o sphere and in soils, and its ecolo gical impacts, all of these factors need to be the focus of this effort. For example, questions like “Is NO 2 a good indicator of oxidized nitrog en in the atm o sphere? Are there others ?” may not even be the ri ght questions to ask if the focus is on total nitrogen and its de position to the ecosystem s (oxidized and reduced). Sam e reasoning m a y also be applicable to SO 2 /total sulf ur.

The Draf t Plan in all of its m a jor Sections (key po licy -re levant issues, s c ie nce

assessm ent, risk/exposure assessm ent, and pol icy assessm ent) does not discuss the issue of how the review process would evaluate the critical load-b ased appro a ch as an alternative to prom ulgating am bient concentratio n-based standards. It appears to m e that this is a m a jor oversight of the Draft Plan. For example, Chapter 8 (the science annex on critical loads, July 2007 dr aft version) quotes the 2004 Na tional Research Council (N RC) report, “ ... However, concentration-based stan dards are inappropriate for som e resources at risk from air po llutants, includ ing so ils, g r oun dwater, surf ace waters, and coastal ecosystem s. For such res ources, a d e position

- bas e d standa rd would be more approp riate. One approach for establishing such a depositi on-based standard is through the use of so4called “critical loads.” At a m i ni m u m, the Dr aft Plan should be revised to describe how it would address critical lo ad-based ap proach.

Finally, I will like th e Dr af t Plan to b e m o re explicit in how th e pr ocess of establishing secondary standards will address uncertainti es in inputs and outputs (em i ssions, CMAQ models, rate constants in atm o spheric chem is try processes, deposition maps, ecosystem s modeling, etc.) and how these uncertainties w ould affect the judgm e nts that m u st be

m a de in recomm ending standards or range of standards. Each of the m a ny m odels that would be used in this process would generate outputs with associat ed uncertainties th at then will be used as inputs for subseq uent m odels across a set of linked m o dules (Appendix B of the Draft Plan describes this pr ocess but at a very cu rsory level). There

are num erical and analytical m e thods av ailable for propagating uncertainty across modules for quantifiable sources of uncertainti es. For uncertainties that are difficult to quantify, there are “scenario-b ased” m e thods that can be used to bound the results. However, propagating uncertainty across m odels and m odul es represents only one part of the puzzle: the results of these an alys es require communication to policy-m a kers and other inte res t ed stakeholders. Uncer tain ty analy s es, particu l a r ly m u lti-dim e nsional ones necessary for establishing secondary standards for SO 2 and NO 2 , can be difficult to communicate and to understand, hindering their use in policy-m a king. To address this, I suggest that the Draft Plan a ddress the issue of qu antifying uncertainty in several m o dels used in the review process and develop an integrated uncertainty analyses and also develop communication tools to ex plain the implica tions of uncertainty in decision

m a king.

5Comm ents from Dr. Andrzej Bytnerowicz

General Co mments

Generally, the docum ent is well written, logically structur ed, and can serve as a good start of discussions on possibl e revision of the NO2 and SO2 NAAQS. The first phase of the process (integrated review plan), as well as th ree oth e r ph ases (Integ rated Scien ce Assessm ent, risk exposure assessm e n t a nd policy assessm ent and rulem a king) are logically and clearly presented.

It would be helpful to clarify what N pollu tants should be discussed as those which may have secondary (welfare) effects. In my opi nion, in regard to th e oxidized N com pounds, we should not discuss only NOx (which is just a sum of NO2 and NO), but rather NO y , which includes NOx and also other gases of a potential ecological importance such as nitric acid vapor (HNO3) or peroxyacetyl nitrate (PAN) (Seinfel d and Pandis, 1998, p. 71). It would be even better if we could use a term “N gaseous com pounds”, since reduced species such as NH3 also ha ve pronounced ecological effects.

I would be even m o re comfortable with a term “welfare effects resu lting from deposition of criteria pollutants (NO2 and SO2) and th eir transform a tion produc ts” (p. 1-7, lines 22- 23).

Changing clim ate should be considered in developm ent of the secondary NO2 & SO2 NAAQS as a m odifier of the ecological eff ects of N and S de position. For exam ple, in

western eco s ystem s the effects of elevated levels of N deposition or am bient ozone (increased above-ground biom ass production, re duced water availability, prem ature foliar

senescen ce) can be enhanced by elev ated temp eratures, drought or winds of higher speed and frequency. All these factors m a y lead to catastrophic fires as those from 2003 and these recen tly observed in southern C a lifornia.

Specific Comments

1. Introduction

Generally Introduction is well written and offers a good basis for the rest of the docum ent.

However, in reference to m y above statem en t, I suggest that on page 1-10, line 5, a change is m a de: “In addition to acidification, NOx and HNO3 act with ...”. Alternatively, it could be changed to: “In addition to acidification, NOy acts with...”

Page 1-12, line 12 –instead of considering NO2 and its transf orm a tion products, it could be better to stress that NOy contributes to N loading of ecosystem s. If suc h a change is

m a de, than HNO3, which provides large pr oportion of oxidized N to ecosystem s, especially in dry clim ate, w ould be autom a tically included.

6Page 1-13. It is a very important secti on emphasizing a need for including reduced N

compounds if deposition and ecolo gical effects are concerned.

Page 1-13, line 14 – recent evidence suggests th at fine particulate m a tter can also reduce precipitation in m ountainous areas of Californi a and elsewhere (Rosenfeld et al., 2007).

3. Key Policy-Relevant Issues

Page 3-1, line 21 – it is not scientifically co rrect to say “particul ate NOx and SOx”. The authors probably had in m i nd N and S aerosol s, including fine particulate nitrate and sulfate.

4. Science A ssessm ent

Page 4-1, line 5, and the following text. Again, more precision is using various chem ical

term s is needed. Criteria pollutants are SO2 and NO2, not NOx and SOx. Maybe a term “SO2 & NO2 and their transform a tion products ” would be more appropriate.

Page 4-2 lines 4 and 5. I would like to suggest that also “gray” li terature, specifically reports, such as those from the UN ECE ICP For e st and ICP Mapping and Modelling dealing with issues of Critical Loads for S, N and acidity c ould also be considered. These reports have been internally reviewed and m a y have an im portant practical value for developing sim ilar approaches in the US.

Page 4-1, lin e s 9 and 10. I would also cons ider recent information from CASTNET and various passive samp ler networks in US a nd Europe, on HNO3 concentrations. In som e areas, inform ation of a m bient NH3 is also b eco m i ng available (m ostly from large-scale passive sampler networks). Inform ation on these two gases, which due to their high deposition velocity provide significant am ounts of N to ecosystem s, could be quite valuable.

Page 4-2, line 25 and 26. Ammonia (NH3) should also be added to the proposed literature search.

Page 4-3, lines 8-21, again, I would like to emphasize again a potenti al value of the ICP Mapping and Modelling and IC P Forests annual reports.

Page 4-3, lines 18 and 19. Modifying effect s of the changing clim atic conditions (in

western con d itions, increasing tem p eratu r e, reduced precipitation and long – term drought) or increasing background concentr ations of a m bient ozone should be considered.

Page 4-5, lines 1 – 16. Passive samp ler ne tworks (for HNO3, NH3, NO, NO2 or SO2) can provid e the recepto r-level d a ta th at can be used for validation of the deposition models. Use of geostatistics (such as ArcGIS Geostatistical Analyst) m a y greatly help in

trans l ating p o int data in to landscap e-level concen tration su rfaces.

75. Risk /Exposure Assessm e nt

Page 5-1, line 8 – the recomm e nded by NRC (2004) cr itical loads approach for N, S ands acidity (already widely used in Europe) c ould be considered. The US FS i s already developing a strategy for m easuring param e ters needed for calculation of CL for N & S on a network of experimental forest and FS-m a n a ged LTER sites (21 sites altogether nationwide).

Page 5-2, lines 5-10. Air polluti on gradient studies or larg e-scale m onitoring/research networks linking information on air chem istr y, deposition and ecologi cal responses could be considered.

Page 5-2, lines 11-15. Responses of ecosystem s to N and S deposition in m e sic (East) and arid (West) clim ates ar e quite dif f

erent and should be better studied. Due to high diversity of the US ecosystem s, an unde rstanding of the o ccurring changes on a continental scale m a y be more difficult than in Europe. In ternational cooperation with partners in E u rope and Asia m a y greatly help in understanding of N deposition responses in two types of clim ate. In addition, res ponses of mountain ecosystem s (forests, subalpine and alpine) should be taken into serious considerati on. Since ecologica l effects of clim ate change in high elevation forests ha ve been very strong in recent years, interactions with elevated N & S deposition and increasing background ozone concentrations shoul d be investigated.

Liter a tur e :

Rosenfeld, D., J. Dai, X. Yu, Z. Yao, X. Xu, X Yang, C. Du. 2007. Inverse relationship between amounts of air polluti on and orographi c precipitation. Science , 315, 9 March 2007, 1396-1398.

Seinfeld, J., & S. N. Pandis. 1998. Atmospheric Chemistry and Physics - from Air pollution to Climate Change . John Wiley and Sons, Inc., New York, 1326 pp.

8Comm ents from Ms. La uraine Chestnut

The draft plan gives a comp rehensive overvie w of the am bitious scientific review and policy assessm e nt process planned by EPA for determ ining what secondary standard

m i ght be appropriate, if any, for the deposit ion related effects of NOx and SOx. I have just a few questions and comments on the policy aspects of this plan.

How much needs to be know n to provide a defensible basis for setting a secondary standard fo r the deposition-re l ated effects of N O x and SOx?

If all the questions articulate d here could be answ ered then the decisions about standards would be fairly straightforward. Difficulties wi ll arise, of course, because current science and analysis tools will not be able to answer m a ny of these important questions. Judgm ents will be necessary abou t whether th ere is sufficien t inform ation to provid e a defensible basis for selecting a secondary standard. Does the secondary standard language provide guidance on this issue? W ith the prim ary standards, the presumption is to be protective of hum a n health, but with public welfare is the presumption the sam e ? Public welf a r e is def i n ite ly impacted by sta ndards that impose costs; so ho w fir m m u st the evid ence be that the s t anda rds p r event an adverse im pact?

The plan m e ntions the need to assess the progress exp ected in reducing deposition precursors as a result of the prim ary NAAQS (e.g., for PM and ozone) and current regulations (e.g., CAIR), but this is an im portant issue that pe rhaps deserves m o re attention. This review of a pot ential secondary standard n eeds to acknowledge that other standard s an d regulatory efforts are alr eady underway that hav e reduced d e position

precurso r s and will redu ce them further in the future. Theo retically, a secondary stan dard could be based on a sim p le determ ination of what level of exp o sure is suf f icien t to prevent adv e rse env i ron m ental effects, indep e ndent of expected future em ission levels. However, it is a relevant policy question whet her such standards are needed to prevent expected future adverse effects or whether current stand a rds and regulato r y efforts are sufficiently protective.

Defining what makes an effect “adverse.”

Obviously, a key step in the standard setting process is determ ining what effects are adverse. The draft m e ntions valuation studies as one way to assess how adverse an effect

m a y be. Although valuation (either monetary or non-m onetary) studies provide som e

m e trics to measure s t ren g th of preferen ce, they do not alone provide sufficient inform ation about what effect m a y be adverse. Ju st because an effect has som e m onetary value (either use or nonuse value), it is not necessarily adverse.

The draft says little about what other m e thods may be useful in assessing whether an effect is adv e rse. It seems like there m a y be m a ny ways to assess this from a biological perspective that would n o t necessitate valua tion. For exam ple, acidificatio n of lakes an d

stream s to the point that som e aquatic speci es cannot survive in those waters could be established to be an adverse effect without necessarily having estim ates of society’s

9monetary valuation for preventing such effects. I think the assessm ent will have to m a ke the cas e reg a rding what constitutes an adverse effect on the biological lev e l reg a rdless of what valuation inform ation m a y or may not be available.

Related to th is is, I think, the issu e of varia tions in sensitivity to pollutants in different locations. Providing all locations the sam e level of protection m a y well necessitate different standards in different locations. Setti ng a uniform na tional stan d a rd at a leve l to protect the most sensitive loca tions would likely be unnecess a ri ly costly. I’m glad to s ee language in the draft that seem s to allow fo r the possibility of st andards that vary by location. However, the assessm ent process will have to take into consideration the practical policy implications of the long-range transport of the pollutants in this case. Meeting a deposition-related standard in one location would necessitate em ission controls in m a ny distant loc a tion s and this m a y lim it the practicality of having very fine tuned location specific standards.

Repairing current inju ry versus maintaining current quality.

The draft mentions the need to assess how be neficial a standard m i ght be in term s of preventing or reducing ecological effects. Th is raises som e questions about how the standard setting process should tak e into accoun t ecological injury th at has already occurred. With pollutants that bioaccum ulate or persist in th e system for long periods of tim e, it seem s that a different standard m i ght be needed in location s where in jury is already sign ificant because lowe r exposures m i ght be needed to allow recovery to occur.

Critica l loa d /carrying capacity ve rsus full do se-response
.

The draf t plan descr i bes all the inf o r m ation th at would be needed for a full assessm ent of the ecological benefits of changes in em issions of NOx and SOx. Although a full quantitative benefits assessm ent woul d be nice, it is going to be ve ry difficult to do and

m a y not be necessary. Perhaps standards c ould be reasonably established based on less than a full benefits assessm e nt. This m i ght be the case, for example, if thresholds or lim its could be determ ined based on the am ount of exposure a system could tolerate without suffering adverse effects. This would ne ed to be assessed in term s of ecosystem services and at what levels of exposure th es e serv ices cou l d still b e m a intained by the system . This would not necessarily require, however, the full quan tif ica tio n ofthe doseresponse relationsh i p between levels of depos itio n and levels of environmental respon se. The linkages between em issions and environm en tal effects would have to be sufficient, however, to establish that there is a caus al link between anthropogenic em issions and adverse environm ental effects of deposition.

10Comm ents from Dr. Ellis Cowling

Very General Comments on these NAAQS Re view Processes

Before dealing with the details of my specific assignm ent during the October 30, 2007 CASAC Co nsultation on the Secondary ( public-welfare based) NAAQS for NOx an d SOx, I would like to offer a few general comm e n ts about these peri odic NAQQS Re view

processes an d the changes that are being m a de in both the or ganization and focus of these reviews.

As described on pages 1-2 of the “Draft Plan ” for the NOx and SOx Secondary standards, the Clean Air Act of 1970 established two genera l goals for m a nage m e nt of air quality in the United S t ates -- protection of human health and protection of public welfare. Section 108 of the CAA directs the Adm i nistrator of EP A to identify and list “air pollutants” that “in his judgm e nt m a y re asonably be anticipat ed to endanger public health and welfare” and to issu e air qua lity cr ite ria f o r tho s e th at are listed – hence the term “Criteria Pollutan t s.”

Section 109 of the CAA further directs th e Adm i nistrator of EPA to propose and

prom ulgate “Prim a ry” National Am bient Air Qu ality S t andards to protect public health and “Secondary” National Am bient Air Qualit y Standards to protec t public welfare.

A secondary standard, as defined in S ection 109, must “specif y a leve l of air quality the attainm e nt and m a intenance of which, in th e judgm e nt of the Ad m i nistrator, based on such criteria, is required to protect the public welfare from any known or anticipated adverse effects asso ciated with the p r esence of [the] pollutant in the am bient air ...” T h e welfare effects of concern include, b u t are no t lim ited to “ef fects on so ils , water, c r op s, vegetation, m a n- m a de m a terials, anim als, w ildlife, weather, visi bility and clim ate, dam a ge to and deterioration of property, and hazards to transportati on, as well as effects

on econom i c values and on personal comfort and well-being.”

So far, the several Adm i nistrators of EPA since 1970 have: 1) Identified six specific “Criteria Pollu tants” – carbon m onoxide, ozone and other photochem i cal oxidants, sulfur dioxide, oxi des of nitrogen, particulate m a tter, and lead – which have thus been designated officially as requiring developm ent and imple m entation of National Am bi ent Air Quality Standards; 2) Emphasized protection of public health as the principal (and overwhelm ingly important) de f a c t o focus of concern within the Ag ency, and public welfare as a (rarely openly acknowledged) but distinctly less important de facto focus of

concern ; 3) Established Secondary (public-welfare -based) N AAQS standards for all six criteria pollutants that almo st always were identical in form (including level, indicator, statistical form , and averaging tim e ) to the Prim ary (public- health based) NAAQS standards for each of these six criteria pollutants; 4) Developed a long-standing trad ition of dealing with th ese s i x specific air pollutants m a inly on a “one-at-a-tim e” basis rather than collectiv ely – i.e., without strong attention to the freque nt interactions and sim u lta neous occurrence of som e of these pollutants as m i xtures within the air in various parts of our country;

115) Maintained a relu ctan t a ttitude abou t the concepts of ecologically based “Critical Loads and Critical Levels” developed in Europe as possible alternative or additional approaches to air-qual ity m a nage m e nt in the US; and 6) Maintained a long-standing general focus on the related concepts of: a) “attainm e nt counties a nd non-attainm e nt counties,” b) “attainm e nt dem onstrations” based on m a them atical m o deling of a lim ited

num b er of exceedance events under extrem e weather cond itio ns, and c) “local anthropogenic sources” as opposed to “both local a nd regional biogenic and anthropogenic sources of e m issions.”

In recent years, in contrast to several of the six ideas listed above, EPA has shown incre a sed willingn ess to think m o re holistica lly – and in m o re fully integrated ways – about both the policy-relevant science and the practical arts of air quality m a nage m e nt aim e d at protection of both public welfare a nd public health. These shifts in both

em phasis and approach have included: 1) Participa tion with othe r f e dera l agenc i es and international bod ies in discussions about the “One Atm o sphere,” “Critical Loads–Critical Levels,” and “MultiplePollutan t –M ultip le Ef f

ects” conc epts ; 2) Adoption of the “NOx SIP Call” in 1999 and both the “Clean Air Interstate Rule” (CAIR) and the “Clean Air Mercu r y Ru le” (CAMR) in 2005 with their more balanced perspectives about both regiona l (interstate) and local sources of

em issions and interactions am ong NOx, SO x, VOCs, “air toxics,” and m e rcury in the form ation, accum u lation, and bio l ogical effects of “ozone and other photochem i cal oxidants,” and fine, coar se, thoracic, and secondary aerosol particle s; 3) Recognition of both f i ne and coars e PM as com p lex and geog raphic a lly v a riab le

m i xtures of sulfate-, nitrate-, and ammonium -dom inated aerosols; natural biogenic and anthropogenic organic substa nces; heavy m e tals including cadm ium

, copper, zinc, lead, and m e rcury; and som e other m i scellaneous substances; 4) More frequent discussion about of th e occurrence and both ecologically-important and public-h ealth im pacts of m i xtures of air pollu tants; and, most recen tly 5) The unprecedented decisions to: A) Prepare and publish in Septem ber 2007 a “ Draft Plan for [si m ultaneous] Review of th e Secondary National A m bient Air Quality S t an dards for Nitrogen Dioxide and Sulfur Dioxide; ” B) Include on page 2-1 of this “ Draft Plan ” a “ Proposed Schedule for Joint NOx and SOx Secondary Standard Review ” with a “Final Integrated NO 2 /SO 2 NAAQS Wor k

Plan ” in D ecem ber 2007 to be followed by preparation and CASAC review of sim ilarly integrat ed NOx/SOx docum ents including: i) an Integrated Science Assessm ent (IS A) to be issued in Decem b er 2008, ii) a Risk/Exposure A ssessm ent (R/EA) to be completed by July 2009, iii) a Policy Assessm ent/Rulem aking docum ent prepared in th e for m of an Advanced Notice of Proposed Ru le Making (A NPR) in August 2009 and Final R u le Making to be com p leted by October 19, 2010; and C) Separate the preparation and revi ew of documentation, the required CASAC and public reviews, and ( possibly also) the final decision-m a king processes

12for a Secondary (public-welfare-based ) NAAQS from the (previously always do m i nating) Prim ary (public-health -based) NAAQS review processes.

Need for Policy Relevancy as the Domina nt Concern in NAAQS Re view Processes

In a May 12 2006 summary letter to Adm i nist rator Johnson, CASAC Ch air, Dr. Rogene Henderson, provided the following statem ent of purpose for these periodic NAAQS review processes.

“CASAC understands the goal of the NAA QS review proces s is to an swer a critica l sc ien tif ic ques tio n: “What evidence has been developed since the last review to indicate if th e current primary and/or s econdary NAAQS need to be revised or if an alternative level or form of these standards is needed to protect public health and/or public welfare?”

During the past 18 m onths, CASAC has particip ated in reviews of three of the existing six cr ite ria p o llutants – p a rticula t e m a tte r, oz one, and lead. C A SAC has a l so joined with senior EPA adm i nistrators in a “top-to- bottomreview” and the resulting recentlycom p leted revision of the NAAQS review proce sses. These two experiences have led to

a seem ingly slight but important need fo r rephrasing and refocusing of this very important “critical scientific question:”

“What scien tif ic ev idenc e and/or scientif ic ins i g h ts have bee n developed since the last review to indicate if the current public-health based and/or the current public-welfare based NAAQS need to be revised or if alternati ve levels, indicators, statistical forms, or averaging times of these standards are needed to protect public health with an adequate margin of safety and to protect public welfare?”

W ith regard to the important d i stinction in purpose of the prim ary (public health) and secondary (public welfare) NAAQS standards, it is noteworthy that in all five cases in which a secondary NAAQS standard has been established, the secondary standard has been set “Sam e as Pri m ary.”

Thus, a second very critical sc ientif ic question tha t needs to be answered -- especially with regard to the present Joint Review of the Secondary Standards for NOx and SOx, as well as the o t her f our c r iteria air po llu tants is:

“What scien tif ic ev idenc e and/or scientif ic ins i g h ts have bee n developed since the last review to indicate whether, and if so, what particular ecosystem components or other air

- quality -re l ated public we lfare va lues, are more or less sens itiv e than the populations of humans for which prima ry standards are established and for this reason may requir e a different level, indicator, statistica l form, o r averaging time of a secondary standard in order to protect public welfare.”

I hope these two “critical scientific questions” will be bo rne in m i nd carefully as CASAC joins with th e various re le vant parts of the Environm ental Protection Agency in

com p leting the upcom ing reviews of both th e prim ary and secondary National Am bient Air Quality Standards for NOx and SOx.

1314 We now have the considerable advantage that a much more complete focus can be achieved in the Integrated Science Assessment th an has historically been achieved in the encyclopedic Criteria Documents that have be en prepared during th e years since 1970.

Thus, I recommend that every chapter of the soon to be completed NOx/SOx Integrated Science Assessment, the Ri sk/Exposure Assessment, and the Policy Assessment/Rule Making documents contain a summary section composed almost entirely of a series of very carefully craft ed statements of Conclusions and Scientific Findings that: 1) Contain the distilled essence of the mo st important topics covered in each chapter, and 2) Are as directly relevant as possible to the two Critically Important Scientific Questions written in bo ld italic type above

. In this connection, I call attention once again to the attached “ Guideline for Formulation of Statements of Scientific Fi ndings to be Used for Policy Purposes. ” These guidelines were developed and publis hed in 1991 by the Oversight Review Board for the National Acid Precipitation Assessment Program. They are th e best guides that I know of for formulation of scientific fi ndings to be used for policy purposes.GUIDELINES FOR F O RMULATION OF SCIENTIFI C FINDI NGS

TO BE US E D FOR P O L I CY PU RPOSES The following gui delines in the form of checklist questions were developed b y t h e NAPAP Oversight Review Board to assist scientists i n form ulating presentations of r esearch r esults to be used in polic y decision processe s. 1) IS THE S T ATEM ENT SOUND? Have the cent r al issues bee n clearly identified? Does each stat e m e n t contain the distilled essence of present scientific and technical understanding of the phenomenon or pr ocess to which it applies ? Is th e statement consistent w ith all relevant evidence – eviden ce developed either thr ough NAPAP research or through anal y s i s of resear ch conducted outsid e of NAPAP? Is the statement contradicted by any i m portant evidence developed through r esear ch inside or out side of NAPAP? Have apparent contradictions or interpretations of available evidence bee n considered in form ulating the statem ent of pri n cipal findin g s? 2) IS THE S T ATEM ENT DIRECT IONAL AND, WHERE APPROPRIATE, QUANT ITAT IVE? Does the

state m ent correctly quantify both the di r ection and magnitude of tr ends and relationships in th e phenom eno n or process to which the state m ent is relevant? When pos sible, is a range of uncertainty given for each quantitative result ? Have various sources of uncertainty been identified and qua ntified, for exa m ple, does the state m ent include or acknowledge errors in actual m e asur ements, standard errors of estimate, possible biases in the availability of data, extrapolation of result s bey o nd t h e mathematical , geographica l, or tem poral relevancy of available inform ation, etc. In short, are there nu mbers in the state m ent? Are th e num bers correct? Are the num bers relevant to the general meaning of the state m ent ? 3) IS THE D E GR EE OF CERT AIN T Y OR U NCE RTAI NTY OF THE ST ATEME N T INDI CA TE D CLEA RLY? Have appropriate statistic al tests been a pplie d to the data used in drawing the conclusion set f o rth in the statement? If the statement is b ased on a m a thematical or novel conceptual m odel, has th e m odel or concept been validated? Does the state m ent des c ribe the m odel or concept on which it is based a nd the degree of validity of that m odel or concept? 4) IS THE S T ATEM ENT CORRE C T WIT H OUT QUALIFICATION? Are there li mitations of time, spac e, or other special circu m st ance s in which the state m ent is true ? If the state m ent is true only in some circu m stanc es, are these li m itati ons described adequately a nd briefly? 5) IS THE S T ATEM ENT C LEA R A ND UN AMB I GU OUS? Are the words and phrases used in the state m ent understandab l e b y the deci sion m a kers of our societ y ? Is the statement free of specialized jargon? Will too many people m i sun d erstand its meaning? 6) IS THE S T ATEM ENT AS CONCISE AS IT C AN BE MA DE WIT HOUT RIS K OF MISUNDERSTANDING? Are there a n y excess wo rds, phrases, or id eas in the state m ent w h ich are not neces sary to comm unic a te the m e aning of the state m ent? Are t h ere so m a ny caveats in the state m ent that the state m en t itself is trivial, conf using, or am b i guous ? 7) IS THE S T ATEM ENT FREE OF SCIENTIFIC OR OT HER BI ASES OR IMPL IC ATI O NS OF SOCIE T AL VALU E JU DGME NTS? Is the statement free of influence by specific schools of scientific thoug ht? Is th e statement also free of words, phrases, or concepts that have politic al, econom i c , ideological, r e ligious, m o ral, or other personal-, agency -, o r organization

- sp ecific valu es, overtones, or im plicatio ns? Does the choice of how the statement is expressed rather than its specific words suggest underly i ng biases or value judgm ents ? Is the t one i m partial and free of special pleading? If societal valu e judgm ents have been discussed, have these judgm en ts been identified as such and described both clearly and obje c tively? 8) HAVE S O CIET AL IM PLICATIONS BEEN DESCRIBED OBJECT IVELY? Consideration of al ternative courses of act ion and their consequences inherently invol ves judgments of their feasibility and the im portan ce of effects. For this reason, it is i m portant to ask if a reas onable range of alternative polic ies or courses of action have been evaluate d? Have societal i m plicati ons of altern ative courses of action been stated in the following general form ?: " If this [ p articular option] were adopted then that [ p articular outco me] would be expected." 9) HAVE T H E PR OFE SSION AL B I ASES OF A U THORS A ND RE VIE W ERS BE E N DESC RIB E D OPE N L Y ? Acknowledgment of potential sources of bias is i m portant so that r eaders can judge for them selves the cred ibilit y of reports and assess ments.

15My Assignment in this CAS AC Consul tation on the Draft Plan for Review of the Secondary Standards fo r Nitrogen Dioxide and Sulfur Dioxide

My specific assignm ent in preparatio n for the October 30 , 2007 CA SAC Consultation on the Draft Plan as outlined in Chairm an Ted Russell’s m e m o of 11 October 2007 is -- K ey Policy Relevant Issues . These topics are covered prim arily in Chapter 3 o f the Draf t Plan and are sum m a rized in the five Overarching Po licy-Relevan t Questi ons on pages 3-1 and 3-2 and the additional policy relevant scientif ic questions presented in Chapters 4-6.

Chairm an Russell also g a ve this same assi gnm ent to two other CASAC pa nel colleagues -- Lauraine Chestnut and Rich Poirot. Thus, I am very m u c h looking forward to

comp aring notes with both Lauraine and Rich during our Consultation on October 30.

There are many parts of Chapter 3 and other pa rts of this Draft Plan showing that both gaseous and particulate form s of the various oxides of nitrogen and sulfur should be included among the “Pollutants of Concern” in this review of the NOx a nd SOx Secondary standards. T h at is good.

As an ecologist, who is aware of the m a ny di fferent and important adverse public-welfare effects of both oxidized and reduced for m s of reactive nitrogen, I was pleased to find that section 1.4.3 of Chapter 1 is ti tled “Ammonia” At first, I thought this might m ean that EPA would be willing to broaden its perspe ctives about the m a ny, diverse, and very significan t adverse welfare effects of reac tive nitrogen pollution by adding ammonia, ammonium i on, and other reduced form s of reactive nitrogen to the “Ind icators of Concern” in this nitrogen and sulfur NOx and SOx joint NAAQS review. But m y hopes were quickly dashed by EPA’s apparent c ontinuing preference (see page 1-13) to consider reduced form s of nitrogen alm o st ex clus ively in the contex t of the PM review

.
Many of us in the ecological community are well aware that atm o spheric deposition of nitrogen and sulfur oxides – but also atm o s pheric deposition of che m ically reduced form s of these same elem ents (especially ammonia and ammonium ion) -- are causing a wide variety of som e ti m e s beneficial and som e tim es adverse effects on terrestrial and aquatic ecosystem s in m a ny parts of our country. These effects include: 1) acidification of lakes, stream s, so ils, and both surface and gro und waters; 2) eutrophication of lakes, stream s, and estuaries, 3) hypoxia in som e coastal and m a rine ecosystem s, 4) changes in biodiversity within som e aquatic and terrestrial ecosystem s , 5) changes in reproduction and age-class distributions of fish populations, 6) changes in the nutrient status of forest tr ees and natural grasslands that som e ti m e s lead to increased growth and productivity but sometim es also cause increased susceptibility to pest and pathogens, 7) decreases in frost hardin ess in som e fo rest tree sp ecies su ch as red spru ce, 8) nitrogen saturation of som e forest soils, as well as 9) decreases in visibility an d increases in regional haze in urban and rural locations as well as in scenic v i sta s in wilderness areas and airports, and

1610) increased deleterious effects on som e building materials and historical

monum e nts of various types.

These m a ny and varied ecological and other pub lic-welfare co nsequen ces of nitrogen and sulfur pollution provide str ong justification for reexam ination of the secondary NAAQS standards for both nitrogen and sulfur. To be sure, inclusion of reduced as well as oxidized form s of nitrogen and sulfur would require a very significant change in the “Indicators of Concern” for either or both of the NOx and/or SOx NAAQS standards.

But it is very clear that the wide range of adverse effects listed a bove fit very well with the definition of “welfare eff ects” specified in section 109 of the Clean Air Act -- “effects on soils, water, crops, vegetation, m a n-m a de m a t e rials, anim a l s, wildlife, weather, visibility and clim ate, dam a ge to and deterioration of property, and hazards to transportation, as well as effects on econom ic values and on personal comfort and wellbeing.”

Also, there is a very larg e body of accum u late d scientific ev idence about m a ny of the 10 different welfare effects listed a bove that have been shown to be attributable to exposures to reduced as well as oxidized form s of both n itrogen and sulfur. In fact, essentially all 10 of the important “Effects of Concern” listed above have been attributed to- or at least are significantly influenced by- both reduced and oxidized form s of nitrogen. Som e of these sam e “Effects of Concern” also are influenced by both reduced and oxidized form s of sulfur. This is true for the 1 st , 5 th , 6 th , 7 th , 9 th , and 10 th effects listed abo v e. Thus, it

m a kes m u ch logical sense – a nd well-justified scientific sense as well -- for EPA to carefully co nsider the p o ssibi lity of broadening the defini tion of the “Indicators of Concern” for the NAAQS for NOx a nd SOx to include both reduced and oxidized form s of nitrogen -- and perhaps also both reduced a nd oxidized form s of sulfur -- as a part of the presently proposed joint science assessm ent for the secondary NAAQS for NOx a nd SOx.

Section 4.1 of this Draft Plan m a kes an im portant and well-reasoned distinction between how the Agency plans to include welfare effects caused by NOx and SOx “and their transform a tion products while st ill residing in the am bient air” in the secondary PM NAAQS review, and thus to include in the present “NOx and SOx secondary NAAQS joint s c ien c e assessm ent” the “welf a re ef f

ects dr iven by the[ se] pollutan t s or the i r transform a tion products once deposited into the environm ent.”

For all of th e reasons ou tlin ed above, m a ny of us in the ecolo g ical community con tin ue to believe that the US and other developed count ries of the world need to consider the estab lishm ent of an integr ated total reactive nitro g en approach in air-quality

m a nage m e nt

. Such an integrated total react ive nitro g en idea was considered in a 1997 E P A report titled “Nitrogen O x ides: Im pa cts on Public Health and the Environm ent.” This docum ent was prepared by a team of scien tists and engineers led by Doug Grano in EPA’s Office of Air and Radiation. Such an integrated appro ach was also recomm ended in a 1998 review paper titled “Optim izing air quality m a na ge m e nt in Europe and North Am erica: Justification for integrated m a nage ment of both oxidized and reduced form s of nitrogen” by Cowling et al (Environm ental Pollution 102 S1 (1998) 599-608).

17During the intervening years, a solid foundation of experi m e ntal work and periodic

reasse ssm ents of integ r ated tota l re ac tive n itr ogen approaches have been presented in a series of peer reviewed journal articl es and focused workshop and international conference reports developed under the auspices of:

 the 1 st , 2 nd , 3 rd , and 4th International Nitrogen Co nferences held in the US and abroad,
 the International Fertilizer Industry Association,
 the UN ECE Convention on Long Range Transboundary Air Pollution (L RTAP),
 the European Comm ission’s Clean Ai r for Europe program (CAFE),
 the Nordic Council of Ministers, and
 the International Nitrogen Initiative (INI).

The Inte rnational Nitrog en Initia tive ( www.initrogen.org ) was started in 2002 as an outgrowth of the 2 nd International Nitrogen Conference. An integrated nitrogen approach and m a nage m e nt of nitrogen was proposed in the Nanjing Declaration, which was an outgrowth of the 3rd International N itr ogen Conference held in Nanjing in 2004.

The following peer reviewed articles and both workshop and conference reports provide important parts of the scientif ic background for consideration of integrated total reactive nitrog en stra tegie s :

Erism a n, J. W., W. de Vries, H. Kros, Oene Oenem a , L. van der Eerden, H

. van Zeijts, and S. Sm eulders. 2001. An outlook for an integrated nitrogen policy. Environm ental Pollut ion and Policy 4:87-95.

Galloway, J.N., J. D. Aber, J.W

. Erism a n, S.P. Se itzinger, R.W. Howarth, and E.B. Cowling. 2003. The Nitrogen Cascade. Bioscience 53:341-356.

Erism a n, J. W., P. Grennfelt, and M. Su tton. 2003. The European perspective on nitrogen em ission and deposition. En vironm ent International 29:311-325.

Erism a n J W . 2004. The Nanjing Declarati on on m a nage m e nt of reactiv e nitrog en. BioScience 54, 286-287.

Erism a n, J.W., N. Domburg, W

. de Vries, B. deHaan, B., and K. Sanders. 2005. The Dutch N-Cascade in the European Perspectiv e. S c ience in China Series C. Life Sciences, 48(1): 1-10.

Erism a n, J.W. 2007. Nitrogen and the C onvention on Long-Range Transport of Air Pollution. http://asta.ivl.se/W orkshops/Saltsjoba den3/Background%20m a terial/JW E _nitrogen% 20and%20clrtap.doc

Erism a n, J.W., T. Spanger, M.A. Sutton, C. Askelssson, S. Am in-Hansjani, H.V. Anderson, H. Apsim on, S. Belyazid, H. Fager li, H. Har m ens, M. Havlikova, J.P. Hettelingh, K. Hicks, L. Horvath, N. Hutchi ngs, M. Maasikm e ts, M. Maione, S. Reis, and C. Stenby. 2007. Nitrogen – integrated environm ental policies. Working Group 5 Report, http://asta.ivl.se/W o rkshops/Sa ltsjobaden3/Conclusions/W G5.pdf

18Grennfelt, P., L. Lindau,. and J. Arnell. 2007. Air pollution and its relationship to clim ate change and sustainable developm ent: Linking imm e di ate needs with long
term challenges. Main C onclusions f r om "Saltsjöbaden 3" Workshop, Göteborg, Sweden, 12-14 March 2007. http://asta.ivl.se/W orkshops /Saltjoboden3/Conclusions/Sa lt3_Final_conclusions_rev8 juni.pdf

Sutton, M.A., J. W

. Erism a n, and O. Oene m a

. 2007. Strateg i es for controlling n i trog en

em issions from agriculture: Regulator y, voluntary and econom ic approaches. International Fertilizer In dustry Association Internati onal W o rkshop on Fertilization Best Managem e nt Practices, Br ussels, Belgium

. March 2007. http://www.fertilizer.org/ifa/publ icat/bap/2007_brussels_fbmp

. asp

Only one of these peer reviewed publicat ions and detailed workshop and conference reports are included am ong the References lis ted in Chapter 7 of the Draft Plan for Review of the Secondary NAAQS for NOx and SOx.

It is im portant to note that these em erging id eas about the need for an “integrated total reactive n itrogen” appro ach al so led to a recent decision by the Science A dvisory Board (SAB) of the USEPA to estab lish a s p ecia l comm ittee of the Board to make a thorough study of reactive n i trogen and its effects on pub li c health and welfare. This comm ittee is titled th e Integrated Nitr ogen Committee ( I NC). It has been at work for most of the past year and is led by Dr. Jam e s Galloway of th e University of Virginia. The 18 current

m e mbers of the INC include a carefully selected group of sc ientists and engineers with broad experience in both air qua lity and water quality aspect s of nitrogen pollution and its

m a nage m e nt

. It is also noteworthy that during the 2007 “Solsjöbaden 3 W o rkshop” cited above, the USEPA joined with other LRTAP signatory or ganizations in proposing that a “Taskforce on Integrated Nitrogen” should be establishe d within the LRTAP Conve ntion to explore integrated reactive nitrogen strategies under the auspices of the LRTAP Working Group on Strategies. In April 2007 the Executive Body of LRTAP decided to implem ent this proposal in 2008 with leaders from the UK and th e Netherlands as co-chairs. This is the first tim e that an integrated nitrogen appro ach has been approved for consideration on a politica l lev e l.

Other Suggestions for Improveme nt of the Secondary NAAQS NOx and SOx Docume nts Yet to C o me
Finally, perm it m e to offer the following addi tional suggestions for impr ovem e nt of t h e Integrated S c ience Assessm ent, Risk/Exposure A ssessm ent, and Policy Assessm ent/Rulem aking docum ents to be com p le ted with the present Draft Plan as an initial gu ide :

1) The term “acidic d e position” used frequently in Chapter 1 sh ould be rep l aced by the m o re accurate term “acidifying d e positi on” o rat leas t the less m i slead ing term “acid depo sition.” Gaseous ammonia, ammonium ion, and both amm oni um sulfate and ammonium nitrat e are all acidifying substa nces even though som e are not acidic w h en they are being deposited from the atm o sphere into ecosystem s

.

192) The answers that will be given to th e well-form ulated and well-focused “overarching policy-relevant questions” listed on pages 3-1 and 3-2 in Chapter 3 and the m o re detailed “po licy-relevant quest ions” listed on pages 4-4 and 4-5, pages 5-5 and 5-6, and page 6-3 will inev itably be incomp lete and or m i sleading with regard to quantitative inte rpre tation of the ca usal “Pollutants of Concern” and the principal “Effects of Concern” if gaseous ammonia, ammonium i on, and other reduced for m s of r eactive nitro g en in both wet and dry deposition are not included in the scien ce assessm ent, risk assessm ent, and proposed rulem a king docum ents.

------------- -------------

Resolution from the Integrated Nitrogen Co mmittee o f th e Science A d visory Board for Consideration by the CASAC S econdary NAAQS NOx and SOx Review Panel

During the ongoing m eeting of the EPA Scien ce Advisory Board’s Integrated Nitrogen Comm ittee (INC) -- m eeting at SAB Headqua rters in W a shington DC on October 29-31, 2007 -- the several m e mbers and Ch air of the INC, Dr. Ja m e s Galloway of the University of Virginia, asked m e (as the CASAC-designa ted liaison person to the S c ience Advisory Board’s In tegrated Nitro g en Comm ittee) to present the follow i ng Resolution (which was developed and approved by the INC) for cons ideration during the CA SAC review of the NAAQS for NOx and SOx during our CASAC Conference Call Consultation on October 30, 2007.



### Resolution

The current air poll u tion i ndi cator for oxides of nitrogen, NOx, is an inadequate measure of reactive ni trogen in the atmospheric environment. The SAB’s Integrated Nitrogen Committee recommends that i norganic reduc ed nitrogen (ammonia plus ammonium) and total oxi d ized ni trogen, NOy, be monitored as indicators of total chemicall y reactive nitrogen.

20Comm ents from Dr. Dougl as Crawford Brown

I am generally supportive of the plan laid out here. This is in part because it is only a sketch of what will be done, and so there is little with which I m i ght disag r ee with res p ect to details, but also because I think the choice s m a de are wise ones. I ag ree with the plan to focus on gaseous phase contam inants since the particulate ones are include in the P M

assessm ent, although I believe it will be VERY difficult to separate out the effects of the gaseous and particulate phase NOx and SOx. I agree with the effects bein g considered

, including the decision to refl ect both direct effects and ef f

ects on natura l s e rvic es (although the latter is by far the m o re conten tious of these tw o classes of effects). The stages of the assessm ent are a l so pro p erly ou tlin e d.

I have som e specific com m e nts to offer at this point:

1. I agree with the decis i on, outlin ed on pages 1-7 and 1-8, to bring NOx and SOx into a linked a sses s m e nt, as it will not b e p o ssible (I be lieve ) to s e p a rate the i r ef f

ects in any studies. Bu t I also m e ntioned above that it will p r ove equally difficult to s e parate the gaseous and particulate phase effects.

2. I was not com p letely clear, even afte r reading the docum ent several tim e s, how

atm o spheric and non-atmospheric loadings will be assessed and incorporated into the analys is. This includ es th e diffi culty of separatin g their attrib utable risk s in the eco log i cal studies that have been conducted. B u t I agree with the need to focus on the atm o spheric loading, so long as this also includes loadings on to a surface that are then washed to an ecosystem through run-off.

3. On page 1-12, it seem s to m e that there is an assump tion (lines 12-18) that all ecosystem changes that cause a shift in spec ies are adverse. I don’t agree with this, and this will be a central question when the assessm ent is perform e d.

4. I liked the fact that the re view is to be focused around a series of “policy relevant questions” (as stated on page 3-1 at the top). This is a wise ch oice because it will result in a docum ent that can serve as the basis for subsequent parts of the NAAQS process. The particular issues described later in th at paragraph are also the appropriate ones.

5. Later on page 3-1, shouldn’t the questions all make referen c e to “gas eou s phase

am bient...” rather than the larg er “ambient”?

6. In the questions at the top of page 3-2, the au th ors m e ntion “effects we are trying to protect...” I assum e they m ean “effect s we are trying to protect against”.

7. On page 4-1, it is claim e d that thousands of papers will be ev aluated. I rather doubt this. On page 4-2, som e of the search te rm s are “terres t rial ecosystem s ”, aquatic ecosystem s”, etc. These will return v e ry larg e po ols of studies, and so I w onder wheth e r they shouldn’t always be paired by NOx and SOx in the search.

218. The criteria on page 4-3 ar e good, although I note that crit erion 6 is both the m o st important and by the far the m o st diffi cult to specify procedurally.

9. On page 4-4, there is m e ntion (and on other pages later) of clim ate change. It was not clea r whethe r this was b e ing inc l uded to try to ass e ss impacts in the f u ture. If so, it m u st also be noted that clim ate change will change transport patterns for pollutants.

10. There are very strong reasons econom i st s give for not believing procedures that estim ate the econom ic values of natural services (as they have discussed w ith respect to the kind of assessm ents perform e d by Bob Costanza). The A g ency should be prepared to offer som e counter argum e nts to these critique s. Most of the criti ques center on the fact that ex isting natura l se rv ices va luatio ns ar e not actually rooted in m a rket phenom ena.

11. On page 5-1, lines 19 and 20, the claim is m a de that the A d m i nistrator m u st m a ke the final decisio n as to whether a giv e n effect is sign ificantly adv e rse to warrant chang i n g the standard. W h ile I m i ght agree with this to so m e degree, I question whether the policy side will understand the science well eno ugh to know HOW adverse a given ecological effect is. The scien ce papers must pres ent this cas e as well, f r om a scien tif ic pe rspective.

12. On page 5-2, the authors ask “To what degree can assum p tions be m a de...” I don’t know what this m eans. Assum p tions can always be m a de. I presum e they m e an “To what degree are assump tions supported by the available science”?

13. On page 5-3 (line 22), the authors m e nti on norm a lizing all ecosystem s. I have no idea what this m eans. It is not the proper phrase.

14. On page 5-4 (lines 25 -30), the d i s c ussi on of overlay ing deposition and im pacts in GIS

seem s to m e m u ch too simplistic. At the le ast, so m e sort of spatia l cor r elationa l

m e thodology will be needed.

15. On page 6-1, lines 21-31, the issues being raised appear to m e all scie nce questions, not policy questions. But the bulleted questions presented on the next pages of this chapter are the appropriate ones for the po licy m a ker to ask of the science..

22Comm ents from Dr. Charles Dr iscoll

I appreciate the opportunity to comments on the EPA Draft Plan for Review of the Secondary National A m bient Air Quality St an dards for Nitrogen Dioxide and Sulfur Dioxide. I received this docum ent late (on l y ye sterday). The advantage is that I have had the opportunity to read everyone else’s co mm ents. Many of the comm ents and thoughts that I have a r e sim ilar to t hose of others on the panel.

In general I am supportive of the docum ent and approach. S o m e of these comments

am plify some of the comm ents of others on the panel.

Reduced nitrogen . I ag ree with the comments of m a ny of the comm ittee m e m b ers that reduced nitrogen should be incl uded in the assessm e nt. Reduced nitrogen species (NH 4 +

, NH 3 , organic N) m a ke s ubstantia l contributions to particulat e m a tter in th e atm o sphere and to the to tal n itrog en loading to e c o system s. Given the magnitude of these contributions it seem s that we should consider these em issions and deposition as part of this as sessm ent.

Linked assessment of nitrogen and sulfur emissions . I also agree with the comm ent s of m a ny of the panel m e mbers that I very m u ch s upport the linked assessm e nt of sulfur and nitrogen deposition, as there are sim ilar pathways for these m a terials and acidification effects are related to th e com b in ed impacts of sulfur and nitrogen. That said in addition to acidification effects, there are fe rtilization effects asso ciated with nitro g en that need to be assessed separately. Another issue that m a y challenge the linked

assessm ent of sulfur and nitrog en m a y be how well th e science is develop e d for each of these elem ents. I m a y be off base here but m y sense is th at th e science m a y be m o re definitiv e for sulfur effects th an nitrogen effect s. This m a y be due to th e longer resid e nce tim e of nitrogen in ecosystem s and the m o re complex ecosystem cycling of nitrogen.

National vs regional control strategies. I ag ree with som e of the panel m e mbers that there m a y be som e advantages as sociated with a regional approach to air quality

m a nage m e nt in the U.S. concerning ecosystem effects. This approach was suggested by the NRC (2004). However, there also appear to be disadvantages to this approach. I am specifically thinking abo u t the recen t NO x Budge t Trading P r ogram (NBP) to control NOx e m issions in the eastern U.S. I believe th a t this ru le was dire cted to control ozone in the East. However, there is a fair am ount of s c ientific literature suggesting nitrogen deposition effects on the W e st. W h ile there are s o m e advantages associated with thes e regional rules they rule the ri sk of ignoring environm ental i ssues in areas of the country where em issions are not controlled.

Positive vs negative effects . I endo rse Dale Joh n son’s comm ents about positiv e and negativ e effects. It is difficult to pas s judgem e nt on what are positiv e and negativ e effects. I think we should simp ly docum ent change and let others decide what are the positiv e and negativ e ef f

ects.

23Extent and rate of reco very. One issue tha t I c a n im agine that will be d i f f i cult to address is th e exten t and rate of “eco s y stem recovery” following reduction s in em issio n s. There is a wide range of sensitivity of eco systems to inputs of atm o spheric sulfur and nitrogen deposition. W i th respect to acidifi cation m a ny ecosystem s are naturally acidic due to inputs of organic acids. In ad dition, the long-term m o nitoring studies and modeling studies suggest that the recovery of ecosystem s following reductions will occur over extend ed tim e scales (e.g., m a ny decades). These two interrelated consideration s will challen g e our ability to establis h secondary standard s for sulfur and nitrog en. Som e ecosystem s are so sen s itive that it is unlikely that they will ever “recover” from e m ission reductions. Likewise, th e recove ry p e riod f o r so m e ecosystem s will lik ely be so exte nded that this will crea te a dif f i cult situatio n.

Methylatio n of mercury . There is a bit of text on th e linkage between m e thylation of

m e rcury and sulfur deposition, but this effect and relative pH effect on fish should be addressed in the assessment.

Specific co mments

1-9, line 28 I don’t like the term occult deposition. Can this be changed to cloud and fog deposition?

1-9, line 31 Should this be bio geo ch em istry?

1-9, line 32 and below. Font change?

1-11 Figure title. Should the figure tit le be in caps or lower case?

1-11, line 12 Change levels to concentrations.

1-12, line 5 Decreases in available base cations...

1-12, line 11 and elsewhere Should section titles be in caps or lower case.

1-12, line 21 On an annual basis, atm o spheric nitrogen deposition may contribute up to 40%....

1-12, line 22-24. I do not unde rstand these sentences.

1-12, line 29. ...addition, increased phytoplankton growth in the water column and on surfaces can attenuate li ght causing declines in subm erged...

24Comm ents from Dr. Paul Hanson

I found the draft plan to be a concise yet fully developed plan for the review of the policy-issues, science, and ri sk/expo sure/po licy assessm ent of the welfare effects of NOx and SOx. The following comments provide editori al comm ents and address som e specific issues that should be considered in the imple m e n tation of the final plan.

Specific co mments:

Pages iv and v: In the lis ting of term s the EPA m i ght denote whic h term s repr esent legal d e f i nition s within th e c ontext of the Clean Air Act or ot her regulatory statutes versus those that are scientific consensus definitions. The definition of biologically relevant indicator should be expanded and clarified. As I read it I wondered if it might alternativ ely be a m easure of organism response to a stressor (essentially the opposite of what is presented)? On the other hand, if it is intended to denote an indicator of pollutant occurrence or exposure to which biological system are known to respond this should be clar ified. Is a biologically relevant indicator the generic version of the chosen st atutory ‘form ’ of NAAQS standards?

Page 1-1 lines 16 and 17 (als o relevant to 1-8 line 20): To avoid m i ssing key science products th at m i ght be relevant to the current evaluation of NOx science, the current scie nce reviews should go back prior to 1995 to around 1991. Much of the resear ch summarized in the previous NOx Ai r Quality Criteria Docum e nt was written and summ ari zed sev e ra l years pr ior to the f i nal p ublica tion d a ta of 1995.

Section 1.4 Som e where in this sec tio n the f e rtiliz a tion po tential of f

o rm s of N deposition f o r terrestrial ecosystem s should be acknowle dged. An evaluation of the impacts of N deposition o n organism s and ecosyste m s will need to recogn iz e that N-d e p o sition responses th rough tim e can proceed along a continuum of response from growth enhancing f e rtilization to grow th depressing conditions associ ate with ad vanced lev e l of N inputs. Excess N-dep o sition resu lts when available N can ’t be ass i m ilated by existing vegetation or imm obilized via soil buffering capacities.

Figure 1-1 should include plant fe rtilization as an end point.

Section 1.4.2 The concept of ‘excess N’ dem a nds a comp rehensive understanding of the biogeochem i cal cycle of N that will be location s p ecific a nd able to capture comp lex interplay between biological productivity a nd N uptake potential and the biogeophysical processes th at sto r e and releas e forms of N and acidity in so ils. A key question for the scienc e asse ssm ents will be -- Do curr ent m odels have the c a p acity to han d le th is

comp lexity?

25Section 4.1 Sim ilar to th e m a nner in which this s ec tion deals with NOx and SOx contributions to particulate m a tter issues (it is sum m a rized elsewhere), Section 4.2 should also describe the issue of NOx as a tropospheric ozone pr ecu rs or. I assum e that su ch a summary

statem ent would conclude that NOx as an oz one precursor is/ handl ed and discussed in the context of the recen t review and AQCD for photochem i cal oxidan t s. The dom inant role of NOx as an ozone precursor may, how ever , still be rele vant in the c ontext a standard setting process for NOx and perhap s shouldn’t be completely excluded during this review.

Page 4-4 lines 25 and 26: This statem ent seem ed vague. I wasn’t sure of the intent.

Page 4-5 lines 1 to 16: A separate bullet on the nature and imp acts of wet and dry deposition m i ght be highlighted. Som e for m s of wet and dry (g aseous) deposition have direct access to biologically activ e plan t inte riors through surface or stom atal uptake. Th is pathway should be contrasted with the soil-m ed iated pathway for biological response.

Section 5.3 Section 5.3 and the questions it raises are very important and should be fully evaluated by EPA and vetted in th e review processes. As with other criteria pollutants, it is an unfortunate fact that funding for the continued developm ent of mec h anistic understanding of welfare effects is lim ited. A comprehensive descrip tion of critical data gaps and research needs is essential to jus tify and prioritize future research needs for NO x and SO x welfare effects.

26Comm ents from Dr. Rudolf Husar

Overall, the draft review plan for the Secondary NAAQS for NOx and SOx is sound and executab l e. In particu l ar, the com b ination of NOx and SOx review process is comm e ndable. In

essence, suc h an integra t ed review plan is c ons isten t with the m u ltifacet ed natu re of welfare im pacts. Also, dividing the review into the f our activ itie s: integ r ate d review plan, science

assessm ent, risk assessm ent and po licy assessm e nt is approp riate. Below are sp ecific comm ents and suggestions regarding the draft plan:

Linking of Science, Ri sk and Policy Assessments : In the review process, addition a l co nsiderati on s hould be given to the interaction between the science, risk and policy as sessm ents. In past NAAQS a ssessm ents, these three assessm ents were condu cted som e what indep e ndently fo llo wing a linear causality chain : (1) Science

assessm ent determ ines the natu re of the po llu ta nt s and their effects; (2 ) Risk assessm e nt draws on the scien ce to quan tif y the risk: P o licy / Regula tion is then developed ba sed on the science and risk assessm e nts. However, policy m a king includes m a ny other considerations beyond the science and quantitative risk asse ssm ent. Therefo r e, in d e velo pi ng a policy-relevant science and risk assessments could benefit from a m o re iterative approach a m ong these assessm ents. For

example, the selection of appropr ia te ind i ca tors m i ght be in f l uenced by the po licy options tha t are being considered.

Comments on Science Assessment :

• In updating the observational evidence since the last NAAQS science review, special consideration should be given for the new sate llite-based observations of NO2 and t o a lesser degree SO2.

• Sim ilarly, the observational datab a ses fr om surface m o nitoring networks should incorporate new data from the aerosol Speciation, AIRNOW a nd NOy networks.

• The above new observations are of partic ular im portance for the validation and improve m e nt of the regional chem ical tran s port m odels used in the asse ssments (CMAQ).

Comments on Risk/Ex p osure Assessments :

• The heavy reliance on CMAQ model for asse ssm ent necessitates th e validation and improve m e nt of the CMAQ m odel perform a n ce. The m a rginal performance of CMAQ for non-sulfur species suggests considerable room for i m provem e nt.

• The statis tical an alys is to generate concen tration-deposition relationships is unclear. Providing further rationale for the approach would be beneficial.

Comments on Policy Assessment: As indicated earlier, the policy ass e s s m e nt could provide considerable guidance on both identifying policy relevant science, as well as policy-relevant risk a ssessm ent. Therefore,

m a king the policy assessm ent more transparen t and also m o re closely linked to other

assessm ents would be desirable.

27Comm ents from Dr. Dale Johnson

I have reviewed the Draft Plan for Revi ew of the Secondary National A m bient Air Quality Stan dards f o r Nitrogen Dioxide and Sulf ur Dioxide, a nd I have so m e substantial problem s with this do cu m e nt as written. Specif i c a lly, I f i nd that the tone is entire ly biased toward the negative im pacts of both SOx a nd NOx, whereas we have known for decades that there are positive ef fect s as well. I am m o re than a little am azed that these consider atio ns continu e to f a il to m a ke it in to review papers and docum ents lik e th is. I n particular, I find absolutely no reference to th e p o ssibility th at inc r eas ed deposition o f NOx, which delive r s th e one nutr i ent m o st commonly lim itin g to te rres t r i al vege tatio n, to increased growth and/or ecosystem “health ”. This possibility has been raised m a ny tim es in various reviews (including som e of m y own, which I am not pushing here, as they are now quite old). I can refer you to two publications that have appeared on the scene since the 1990’s that I think are par ticularly significant. Kauppi et al (1992) evaluated forest

m e nsurational data for Europe over the pe riod 1970 to 1990, and found, contrary to what we were being told in the 1980’s, that th e growth of European forests had been increasing, not decreasing, over this period. They speculated that this could be due to bette r silvic ultur e , increased nitrog en depositio n , and perhaps increasing levels of

atm o spheric carbon dioxide. More recently, Magnani et al (2 007) concluded that forest net carbon sequestration in the Northern Hem i sphere “ is fou nd to be overw helmingly driven by nitrogen dep o sition, largely the result of anthropgenic activities ”. Given the high visibility of increasing atm o spheric carbon dioxide levels and clim ate change, I

am am azed t h at th is kind of consideration is lacking in the do cum e nt. Yes, one could argue that the Magnani article is too new to have m a de it in yet, but there is the Kauppi article as well as s e veral other o l der o n es suggesting that N deposition enh a nces fores t C sequestratio n (see th e M a gnini article for thes e references). To be even handed, the report should also consider the Nadel hoffer et al (1999) ar ticle, which dism isses the possibility of nitrogen deposition increasing forest growth by contending that it is mostly tied up in the soil, given our experience in fertilizer st udies. (I personally dis pute that, as nitrogen deposition, unlike fertilizer ap plied nitrogen, can be directly taken up by foliage.)

I m a ke these statem ents with absolu tely no pol itical axe to grind at all – I am NOT ant i

environm entalist, and I am NOT in favor of allowing pollutants to run rampant. And I most certainly do not deny the existence of N- saturation and negative effects of too much N depositio n – I have se en such th in gs in m y own resea r ch. My only m o tiva tion is th at this docum ent give a balanced view of the e ffects of these po llutant s and consider both the pluses and m i nuses of them . I ha ve been m a king the sam e point in various m eetings and reviews for a couple of decades n o w. To not do so is to inv ite ev en m o r e scath i ng review com m e nts from i t s detractors at a later time.

Specific Comments:

p. 1-10, lines 5-8: Fertilizer is m e ntioned he re, but only in a negative context – why do you suppose that people bother to m a nufacture fe rtilizer then? To poison the environm ent or to prom ote positive growth responses?

28p. 4-2, lines 24-26: I believe that the key words should include “sulfur” and “nitrogen” as well. The ke y words lis te d here will a u tom a tically steer towar d negativ e p o llutant ef f

e cts and leave out basics.

p. 5-3, lines 21-32: This secti on comes the c l oses t to an ob jec tive ev alua tion in tha t it leas t consid ers the po ten tia l f o r nitro g en uptake.

p. B-9, lines 11-23: Should include potential increases in C s e questration here.

p. B-14, Diagram : Am az ing that the “Altering plant nutrients” box m e ntions Ca, but not N! “Altering of Production” “Food and Fiber” and “Carbon sequestration” are all shown here, but given that the only reference is to Ca (presum a bly in a negative context), I

presum e that only negative effects of N on all these results are being considered.

p. B-16, Diagram : This diagram m a kes the m o st sense of anything I have seen so far – crop (or forest) yield increases with N f e rtiliza tion

, but, inev ita bly, so does nitr ate pollution. T h is is the kind of balance that ough t to be present in th e entire docum ent.

References:

Kauppi, P.E., Mielikäinen, K. and Kuusel a, K., 1992. Biom as s and carbon budget of European Forests, 1971 to 1990. Science, 256: 70-74. Högberg, P. 2007. Nitrogen impacts on forest carbon. Nature 447: 781-782.

Magnini, F., Mencuccini, M., Borghetti, M., Berb igier, P, Beringer, P., Delzon, S., Grelle, A., Hari, P., Jarvis, P.G., Kolari, P ., Kowalski, A.S., Lankreijer, H. Law. B.E., Lindroth, A., Loustau, D., Giovanni, M., Moncre iff, J.B., Raym ent, M., Tedeschi, V., Valentin i, R. and Grace, J. 2007. The hu m a n footprint in the carbon cycle of

tem p erate and boreal fore sts. Nature 447: 848-850.

Nadelhoffer, K. J., B. A. Emm e tt, P. Gunde rsen, O. J. Kjønaas, C. J. Koopm a ns, P. Schleppi, A. Tietem a, and R. F. W r ight. 1999. Nitrogen depos ition m a kes a m i nor contribution to carbon sequestration in temp erate forests. Nature 398:145-148.

29Comm ents from Dr. Donna Kenski

Overall, this was an excellen t plan fo r m oving for w ard with a comp rehensive review of NOx and SOx effects on ecosystem s. It wa s we ll written an d logi cally presented. I thought the posing of policy releva nt issues in Sec. 3 was particularly well done. There were two significant shortcom ings that I hope ar e addressed in the ISA. First, this plan didn’t explic itly m e ntion any assessm ent of the sp atia l sca l es o f susceptib le ecosystem s. Som e ecosystem s and parts of the country are more vulnerable than others to the effects of acidification and deposition. These should be clearly id entified and their degree of susceptibility depicted, ideally with m a ps. Conceivably, a secondary standard for deposition m i ght be different for various pa rts of the country, to adequately protect sensitive e c o system s but allow f l exibility f o r regions with m o re ecological resilience. The whole process is crying out for a GIS analysis that could overlay and really integrate the deposition data with the ecosystem data, em issions data, valuation data, etc. – i.e., build an atlas of relevant inform ation. Once that inform ation is gathered together, GIS

based spatial analysis tools can be used to extract m a ny m o re insight s f r om the colle c tion of

data. Note that un cer tainty in this spatial inf o r m ation can be incorpo r a t ed in to this kind of analysis. Sectio n 5.3 does mention that a GIS approach will be u s ed, but alm o st as an aside. It should play a m u ch more centr al role in the presenta tion and integration of findings in the ISA.

Second, I’m confused about the ex tent to whic h NH3/NHx will be add r essed in the ISA. It rates a paragraph in section 1.4.3 that announc es it will be ‘considered’, but then it is barely m e ntioned again. It is unrealistic to cons ider ac idif ica tion effects of NOx and SOx without NHx, whic h also plays an impor tant role in acidification. Because the chem istry of NOx and SOx are inex tricab ly linked to NHx, it needs to be addressed explicitly. I do not believe that it can be dism issed by noting that its role in aeroso l f

o rm ation will b e addre s sed in th e PM ISA. It p l ays an importan t role in tota l nitroge n deposition that has to be discussed in detail here, in the context of all the important species. It m a y well be that a m o re suita ble secondary standard includes all nitrogen species, not just NOx; thus to leave it out of the ISA process would be a serious om ission.

Science Assessm ent, p. 4-1, 2 nd and 3 rd paragraphs: It’s not very clear how this organization of the annexes will b e d one, with respect to summ arizing the thousands o f studies. There is bound to be a good deal of overlap am ong studies (since som e studies will add r ess more than o n e effect be ing summarized—e.g., b o th acid i fication and nonacidification effects) so having a well-thought out plan for presenting these that

m i ni m i zes duplication among the various annexe s would be useful. Another suggestion is to be rigorous in separati ng the discussion of new data from the review of old studies – this was a m i nor shortco m ing CASAC identifie d in the recen t review of th e NOx primary ISA that could be avoided here.

Section 4.2.2: These criteria for evaluating th e studies are eminently reasonable. I w ould urge the authors to err on the side of being m o re selec tive, rather than m o re inclu s ive, to keep the ISA and annexes to a m a nageable size if there really are t housands of studies to review.

30p. 4-5: Is there a particular significance to the underscored text? Item 2.g needs to be reworded; in sert ‘and’ b e tween pollution and variations?

Sec. 5 and App. B: In several places this plan emphasizes that the Adm i nistrator will

m a ke the final decision on the standard a nd judge whether an effect is significantly adverse, factoring in the inhe rent uncertainty in the inform ation. Yet there doesn’t seem to be a clear plan for descri bing and quantifying uncertainty at the various stages of this process, inte grating tha t uncertainty across th e process, or for clea rly identifying what is and isn’t an adverse effect. Reasonable people m i ght disagr ee about wh at cons titu tes an adverse effect and how to value it – nitrogen deposition on a far m fi eld might be seen as favorable, w h ile the sam e nitrogen deposition on an adjacent forest m i ght be considered adverse. The inform ation in Appendix B on ecosystem services and valuation presented an interesting fra m ework for beginning to m a ke these as sess m e nts, but it wasn’t clear who gets to m a ke the valuation decisions. Is EPA planning to conduct a survey? Or is this data that’s already been collected ? If the valu ation part of the assessment is carried out correctly, it shouldn’t be up to the Adm i nist rator to judge whether an effect is adverse or not. The point of the exercise is to ta ke this judgm e nt out of the policy realm and apply a quantitative and nonsubjective m e thod to determ ining value.

Sec. 6: Does this first paragraph (p. 6-1) m ean that discussion of the possible form of the standard won’t be discussed in the IS A or REA? If so, that is a distinct shortcom ing. Analysis of the m a ny opt ions for regulating depos ition needs to be part of the ISA. There is no reason to put it off to the last part of the process. It is nice to se e tha t total nitrog en is consid ere d as a possib l e ind i cato r , and th at the seasonal v a r i ability of de position m i ght justif y a s e a s onal standa rd; tem poral variability was only briefl y m e ntioned in the rest of the plan and yet it m i ght be an important risk driver. Sim ilarly, as I noted above, it seem s reasonab l e to think th at a st andard might differ regionally due to broad differences in ecosystem susceptibility. This concept is touched on as well on p. 6-3, but the sooner these poss i b l e form s of the standard are discussed the better.

Appendix B: This was a helpful description of the various tools, but it’s not clear how they all fit together, since the m odels cover a broad range of spatial and temporal scales. Perhaps a schem a tic of the m odeling process would be useful.

p. B-5: Not clear why this section on AIRQ uest is here, whether AIRQuest exists, or whether it is being developed as part of this process. In any event, a database of national air quality monitoring data al ready ex ists (EPA’s AQS). However, it does not include much data on non-criteria species like NH 3, NO, NOx, etc. Those m i ght need to be gathered from other sources. In particular, data from Canada m i ght be useful, as well as satellite observations or speci al study data. The Midwest RPO has collected am bient NH3 data for several years.

p. B-14, line 18: what is W T P?

31Comm ents from Dr. Myron Mitchell

GENERAL COMMENTS

The docum e n t generally does a very good job of developing a protocol for developing secondary national am bient air quality standard s for nitrogen dioxide and sulfur dioxide. The rationale for evaluating concom itantly the in teractions of nitrogen dioxide and sulfur dioxide needs to be separated with respect to atmospheric versus other ecosystem processes. Exam ining together sulfur and ni tro g en chem ical species in the atm o sphere due to the important linkages of these chem ical species is a useful appro a ch.

Careful attention will be needed for quantif ying the differential eff ects of nitrogen and sulfur atm o spheric inputs on ecosystem response. The interactions of nitrogen and sulfur inputs in affecting soil, m i cr obial and plant processes differ between these elem ents. Their respective biogeochem i cal transfor m a tions and fluxes are relati vely distinct from each other. It will be ch alleng ing to devel op app r opriate m e trics that capture the essentia l ecosystem features that determ ine: 1) whet her nitrogen and sulfur inputs by atm o spheric deposition will be lost or retained ; and 2) th e in f l uence of these two ele m ents and their different chem ical species on other factors including recove ry from acidification and loss of nutrients. This will b e particularly im portant for evalu a ting long-term effects on the availability of base cation nutrien ts including calcium and magnesium

.

The current docum ent does not clearly a ddress which soil chem ical and physical characteristics need to receive pa rtic ular a tten tio n in the developm ent of standards and how spatia l varia tion in these cha r acteris tic s w ill be incorpo r a t ed in the de term inations

. For sulfur, attention will be needed on the adsorption/desorption responses in soils. In addition, the contribution of any internal S sources (both organic sulfur m i neralization and inorganic sulfur m i neral weathering) to su lf ate f l uxes in s o il and the r e sultant differences in responses to decreases in sulfur dep o sition in su rface and ground waters will need so m e consideration. In co ntras t fo r nitrogen, m o re atten tion will need to focus on what soil features including how organic m a tter quality af fects m i crobial p r ocess e s

. This asses s m ent will also need to b e linked to the role of ve getation both with respe c t to nitrogen cycling, but also in affecting organic m a tter quality via organic m a tter inputs to the soil.

It will be critical to look at other factors including c lim ate change, invasions of exotic species and the alterations of species com position (especially wood vegetation) that will be occurring concom itantly with changes in atm o spheric deposition of sulfur and nitrogen. Such considerations will be needed to help clarify othe r facto r s that will be separating how other long-term trends are influencing ecosystem response.

Inform ation is provided on the CMAQ (Co mmunity Multi-Sc ale Air Qua l ity) m odel especially in Appendix B. A clear delinea tion of how the CMAQ m odel c o m p ares and/or differ from other m odels including that being used by CASTNET for estim ating deposition at individual sites would help uni fy v a rious app r o aches th at are evaluating

atm o spheric deposition. It m a y also be usef ul to include some review of how these

32efforts comp lim ent or differ from efforts in o t her regions including those taking p l ace in Europe.

The consideration of ecosystem services as a factor to be evaluated in developing the standards could be helpf u l. However, it will likely be necessary to clearly identify early in the process of developing these new standa rds those services that are m o st relevant with respect to the effects of nitrogen and sulfur deposition.

DET A ILE D COMMENTS

Page 1-2, line 7: "whose" should generally be reserved for refe rence to individuals. Replace with "of which".

Page 1-3, line 9: subscript x

Page 1-5, line 6: insert “ic” (acidic v s . acid)

Page 1-6, line 6: where is the be ginning of the quoted statem ent?

Page1-8, line 1: subscripts here and throughout docum e nt.

Page 1-9, line 2: add an “s” to detail

Page 1-9, lin e 15: rep l ace “Once” with “After” and “com p lete” with “com p leted”

Page 1-9, line 28: re p l ace “or” with “and”

Page 1-9, line 30: consider “Depos ition of other chem ical species...”

Page 1-9, line 31: replace “biochem istry” with “biogeochem i stry”

Page 1-9, line 32: from t h is point on the font changes through line 8 of page 1-10.

Page 1-10, lines 1-3: consider sepa rating these statem ents to read as “Acidification results in a cascad e o f eff ects that alter biogeo c hem i cal cycles and harm terrestrial and aquatic ecosystem s. These effects includ e slower gro w th, the death of forest vegetation, and ...”

Page 1-10, line 5: replace “such as” w ith “including”

Page 1-10, line 8: disease is a very general term . Either be more specific or delete.

Page 1-11: in the figure also in clude the charge o n SO4 for soil pro cesses.

Page 1-11, line 9: should read “Acidic deposition”

33Page 1-11, line 12: consider “toxic to both terrestrial and aquatic biota”

Page 1-12, line 1: consider “organism s ” vs. “species”

Page 1-12, line 7: could read “i n the case of Ca, Mg and K, the role of these essential...”

Page 1-12, line 8: could read “... nutrien ts especially in comp a r ison with A l concentrations have...”

Page 1-12, line 15: change to “m ore nitrogen-lim ited”

Page 1-12, line 16: could read “... changes in the ability of invasive species to colonize...”

Page 1-12, line 20: “that is ultim a tely...”

Page 1-12, line 23: replace “places” with “locations”

Page 1-12, line 24-25: could read “... ecologica lly important, m a y play a more important role than indicated by the annual average concentrations.”

Page 1-12, line 28: could read “other popul ation changes which can cascade throughout the food web.”

Page 1-12, line 29: om it “off”

Page 1-12, line 30: “...which serves as an important...”

Page 1-13, line 7: replace “nitrogen” with “amm o nium ”

Page 1-13, line 10: replace “gives” with “increases”

Page 3-1, line 4: could read “In this review of the ecosystem -related effects on public welf are re lated to NO x and SO x ...”

Page 3-1, lin e 6: rep l ace “the” with “this”

Page 3-1, line 16: inse rt comma after “i.e.”

Page 4-3, 4.2.2 includes questi ons so should this paragra ph end with a question m a rk? Page 5-3, line 9: “correlation” would suggest a som e what weak statistical approach. Consider changing to “relationships”

Page 5-3, line 10: This w ould suggest a strong approach; see previous comment.

Page 5-3, line 12: inse rt comma after “i.e.”

34Page 5-3, line 28: W h at is implied by soil type and characteristics? W ouldn' t it be better to use the more general te rm of "soil properties"?

Page 5-3, lines 30-31: shoul d read “... characteristics, which m a y help as sess sensitivitie s, include... ”

Page 5-4, lin e 2: om it “a”

Page 5-4, line 26: replace “num erical” with “sim ulation”

Page 5-4, line 30: inse rt comma after “i.e.”

Page 5-5, line 12: should read “Can deposition models...”

Page 5-5, lin e 12: Should n ' t occult deposition b e included as well?

Page 5-5, line 26: should read “... into services being beneficial to ecosystem s.”

Page 5-5, line 30: should r ead “... results in specific benefit to ecosystem s?”

Page 6-1, line 23: Abundance is a weak te rm . Would nitrogen avai lability or another

term be better?

Page 6-1, line 25: Can this be m a de more explicit.

Page 6-1, line 26: replace “depth of soils” with “s oil cha r ac ter i stics”

Page 6-2, line 1: should read “... su lf ate and other acidifying components...”

Page 6-2, lin e 2: should read “s oil co nstitu ents in cluding su lfate...”

Page B-2: How does CMAQ comp ar e and/or differ from the model being used by CASTNET for estim a ting deposition at indi vidual sites? Shouldn' t the docum ent be consistent w ith respect to use of SI vers us English units? E l se where in the docum ent "m iles" are used.

Page B-9: p a ragraph B.1.3: Shouldn ' t those eco s y stem services that will be evaluated be clearly id entified early in the proce ss of developing the new standards?

35Comm ents from Mr. Richard Poiro t

Comments on Chapter 3. (Key Policy-Relevant Issues) 1. Alternative Indicato rs. There is very encou r aging discussion in Chapter 3 and elsewhere advocating broadened definitions of SOx and NOx, and of possible new (secondary NAAQS) indicators for these pollu tants – separately or com b ined - to specifically include not just gaseous NO2 and SO2, but also (som e of) their various transform a tion products. However, the disc ussion of alternative indicators seem s unnecessarily vague, and m i ght benefit from m o re specific examples. It’s not clear how far the Agen cy m i ght actually be able (or wil ling ) to depar t f r o m the trad itional pra c tic e s of considering only direct effects of and/or indicators based on gaseous NO2 and SO2. Could, for example, a new indicator be:

- Total atm o s pheric oxidized sulfur (sum of S from airborne SO2 and SO4)?

- Total atm o s pheric oxidized nitroge n (sum o f N from NOy & NH4NO3)?

- Total (wet, dry and occult) depositi on of oxidized atm o spheric sulfur?

- Total deposition of atm o spheric nitrog en (or at least oxid i zed nitrog en)?

- Exceedance (by X %) of critical lo ad for atm o spheric su lfur d e position ?

- Exceedance (by X %) of critical lo ad fo r total sulfur + nitrogen deposition ?

Has this current consideration of NAAQS indi cators based on transf orm a tion products of “criteria” pollutants has always been an option, or is it inspired by the clarifying definition of welfare effects added to S ection 302 (h) of the 19 90 CAAAA (“...whether caused by transform a tion, conversion, or com b ination with other air pollutants”)?

The question of whether “total nitrogen deposition” – includ ing both reduced and oxidized form s – is on (or off) the table as a po te ntia l indicator is of particular interest. Discussion under “Policy Assessm e n t” in Chapte r 6 (P. 6-1ines 21-31) suggest that yes, it’s on the ta ble ( i .e. the r e’s a potential to consider and possibly control ammonia

em issions here). If so, this should be identi fied up front as a key science/policy issue in the ISI and not withhe ld f r om public disc uss i on until the (po licy a ssessm ent) ANPR.

The possible use of critical load s (also explored in m o re deta il in the Chapter 6 discussion of the planned policy assessm ent) raises an im portant question of whether site -spec i fic conditions o f receptor lo cation s could be in corpo r ated as a co mponent of a secondary NAAQS indicator. Expressing a secondary NAAQS as a lim it (absolute or %) by which a critical load for S (or N or S+N) sh ould not be exceeded m i ght allow for a “uniform ”

num b er to be applied nationally which w ould have substantially different regional im plications. Is this option on the table?

A related question is whether se parate standards m i ght be a pplied to different areas (for

exam ple Class 1 W ilderness areas as suggested on p. 5-3, line 32). Conceivably, it m i ght be possible to specify, or propose a process fo r identifying, “sensitive areas” where m o re stringent standards m i ght apply. This rem i nds me to point to an inform ative new Forest Service-supported critical loads web resource at: http://nrs.fs.fed.us/tools/cl/hom e.htm and to suggest that EPA m i ght do we ll to seek collaborative assist ance from the FS and NPS in this secondary N AAQS review.

362. Sulfate & Nitrate Aerosols. There’s a clearly stated inte ntion to avoid consideration of public welfare (prim a rily visi bility ) ef f

ects of sulf ate and nitra t e aerosols in this rev i ew – but rather to address these only in the upcom ing PM review. The details of and reasons for this separation aren ’t clear, and I don’t see wh y a section focusing on “the vis i bility effects of sulfate and nitrat e aerosols” couldn’t be devel oped and copy/pasted into both the secondary SOx/NOx and the PM ISIs (and environm ental risk as sessm ents). Good

argum ents could be m a de on both sides of the is sue of whether vis i bility ef f

ects can b e st be addressed through secondary PM2.5 or secondary SOx & NOx standards (or especially th e com b ined sulfat e+n itrate standards that s eem to be on the table here for deposition- r e lated ef f

ects). But th is inte resting a nd potentially illum i nating science/policy discussion (and resulting policy options) would be precluded by an advance dec i sion th at on ly one appro ach will b e c onsidered.

The nature and logic of this division isn’t stated very clearly. Page 3-1, lines 19-21, indica te th at “this review will f o cus o n the ecosys t em -related welf are ef f

ects th at r e sult from the deposition of these pollutants and tr ansform a tion products in the gas-phase....” Does this mean tha t wet, occult and particle -phase deposition of these pollutants will not be considered here? Do visibility eff ects from light absorption by gaseous NO2 belong in the PM review? The first paragraph on pa ge 4-1 describes som e what more clearly the intended division of effects associated with pollutants suspended in the ambient air (only considered under PM) vs. pollutants which have been deposited to the environm ent (considered here). However, no justification is provided for this division. Babs by NO2 still falls through the cracks, particulate-ph ase N H 4NO3 is often partially lost by P M 2.5

m a ss m easurem ent m e thods and undergoes rapi d and frequent tran sform a tions to and from the gas phase. Sulfates + nitrates accoun t for a m a jority of visibility im pair m e nt nationally, are typically the m o st “anthropoge nic” (and controllable) of m a j o r PM and visibility-impairing species, are (nearly) uni que as water-absorbing PM species, greatly enhancing their scattering efficiencies comp ar ed to m o st other species (although water is inten tiona lly disrega r ded in PM m easurem ents). The aeroso l inform ation is also a critical

com ponent of the S & N transform a tion, tran sport, air quality characterization and deposition stories – all of which need to be includ ed here ev en if aerosol effects are disregarded. Conceivably a gas+aerosol, S+ N ind i cato rm i ght corre late well with bu t b e easier to implem ent than one based on deposition or critical loads.

At a m i ni m u m, there needs to be a m o re cl early-stated (and convincin g) rationale for the predeterm i ned avoidance of secondary aerosol ef fects. A section focused specifically on sulfate+n itrate vis i bility eff ects (& pro & con vs. an unspeciated PM2.5 in dicato r) sho u ld be included in the PM docum e nt (and given high tim e priority, since that review lags this one). This review should include a pointer to that section in the PM doc (or just include it as an appendix here). Bu t m o st importan tly, th ere need s to be a way to include consideration of aerosol e ffects in developing alternative environm ental exposure characterization and risk assessm ents, such that a policy decision can be based on understand ing aerosol and other ben e fits of alternative d e pos ition

- based s t andards (or deposition benefits of speciated ae ro sol + gaseou s standards, etc.)

373. Title IV and CAI R. The CAA Ti tle IV SO2 and NO2 e m i ssion cap and trade

program with its pending CAIR extension is the 800 lb. gorilla lurki ng in the corner of the room , while the plan avoids m a king eye c ontact. I think it would be important to include a discussion of these programs in the Chapter 1 revi ew of regulatory history, and to then address som e associated policy-relevant issues in Chapter 3. SO2 NAAQS we re last reviewed in 1988, following a decade of exte nsive, prioritized acid rain research and just as the 1990 CAA de tails were being deve loped. A (m uc h) tighter secondary (and/or prim ary) NAAQS (for SO2 and/or its tran sformation products) would have been an effective way to achieve the sam e emission re ductions that have been achieved by Title IV – perhaps in a shorter tim e fra m e or in a way where envir o nm ental be nef its ra ther than polluter’s profit m a rgins were m a xi mized. W e s eem however to now be stuck indefinitely with an allo wance-based cap and trade pr ogram as the only way that SO2 and NOx

em issions will b e controlled in the f u ture (and EP A’s f o rm er “Acid Rain” Division is now the “Clean Air Markets” Division).

Air quality-based, depos ition

- based or effect s-based standard s are at odds with an

em issions-based trading program , since the la tter approach as sum e s all em issions are equal in space and tim e , while the form er approaches assum e som e locations or tim es are more important than others. How revised NAAQS for SOx/ NOx and transfor m a tion products m i ght interact with, comp lem e nt or m o dify existing and future em issions trading

program s could be an interesting and in form ative area for futu re science/p o licy discussions, and should be emphasized in this NA AQS review cycle rather than avoided. Even if cap & trade rem a ins our p r eferred o r exclusive con t ro l approach in the future, the tim ing and m a gnitude of the cap(s) could a nd should be guided by health , welfare an d environm ental protection needs. Considerati on should also be given to extension of or alternatives to these program s for the W e stern half of the country, for which Title IV and CAIR have not reduced em issions.

In considering current and projected future environm ental and other welf are effects, and associated alternative secondary NAAQS, the Ag ency will want to consider historical deposition b u rdens (gen erally declin ing si nce the m i d 1970s, well before Title IV) an d projected future reductions from CAI R (or other on-the-way program s). The environm ental responses – first in concentr ation and deposition and later in biological indice s – to recen t (primarily) downward tr ends in em issions can provid e comp elling evidence of causal relationships. And evalua tion of the rates and extent of biological recovery will want to take into account bot h current and projected f u ture loading ra tes.

Specific Comments on Chapter 3 P. 3-1, lines 17-24: You could change “par ticu l ates” in line 1 8 to “transf o rm ation products” for a m o re inclusive term . Or if you intend “NOx and SOx” here to m ean all gaseous precursors and gaseous transfor m a tion products, then this is inconsistent with the

term “NOx and SOx particles” in line 22. It’s also unclear what “gas-phase” in line 20 applies to. I assum e you plan to consider effects contributed by deposition of gaseous, particulate and precipitation-bound pollutants.

38P. 3-1, lines 26&27: The term “a m b ient” on line 26 isn’t quite ri ght unless you add “and their transform a tion and deposition products” after “SOx” on line 27. I think you want to specifically include d e p o sition effects but avo i d considering effects fr om the pollutan t s in the “am bient” air (or at least that’s what you say on page 4-1).

P. 3-2, line 1: You could add “soil a nd bedrock geology,” af ter “conditions,”.

P. 3-2, line 6: You could add “or de position ” af ter “a ir qua lity”.

P. 3-2, line 22: You could add “effects from ” be fore “deposition” and change “sulfates” to “sulfur compounds” (presum a bly you intend to include effects from SO2 deposition).

P. 32, lines 30-31: The parenthetical expr ession relating to long- term impacts from current and cum u lative loadings is clearly relevant to a NAAQS review, but isn’t necessarily a subset of this bullet on e ffects of varying m e teorological & clim atic conditions. I suggest b r eaking it out as a separate bullet and p u tting it bef o re the on e that considers met & clim ate variab ility (or long-term change).

Comments on other sections

Chapter 1 P. 1-4, lines 25-27: This ‘logic’ – that th e r e were insuf f i cient data to estab lish a quantitative relationship between SO2 and vege tation effects – seem s to be necess arily based on an assump tion that it was necessary th at gaseous SO2 be the indicator. Has this

assum p tion changed and why?

P. 1-5, lines 25-26: I do n’t th ink “p rem a ture an d unwise” are accurate d e scrip t ors (unless m odif i ed by the term “politic ally” ) f o r EPA’s reluc t an ce to pr escr ibe any regulatory control program for sulfur oxides in 1988 - considering th at the Agency has estim ated (m idrange estim ate in 1999 repor t) econom i c benefits of the 1990 CAA Am endm ents (which inc l uded the 10 m illion ton cap and trad e SO2 reduction) of $11 0 Billion, and curren tly estim a tes that increm ental benefits fro m additional future SO 2 and NO x reductions in from the Clean Air Interstate Rule (CAIR) “will result in $85 to $100 billion in health benefits a nd nearly $2 billion in visibili ty benefits per year by 2015 and will subs tantially reduc e prem ature mort a lity in th e eastern Un ited States. ” ( http ://www.epa.gov/in terstateairquality / ).

I do think that at that point in tim e (1988) , the Agency was (unders tandably) politically reluctant to act because Congress was actively debating ‘acid rain control legislation’ (& had been for the preceding decade), and the Ag ency was working on an interna l plan that becam e the basis for the Title IV cap & tr ade pro v isions of th e 1990 CAA Am endm ents. Twenty years later, it appear s that the predeterm i ned polic y is that SO2 and NOx should be controlled prim arily through em issions-bas ed cap & trade and not by effects-based NAAQS.

39P.1-9, line 18: Generally, the clarity of this “science prim er” section would benefit from

som e editing, for example:

P.1-9, line 2 1 : Change “generally accepted s c ien ce” to som e thing lik e “th e m o re recent
peer- r eviewed scien tif ic litera t ure”...

P. 1-9, line 25: You could delete “m ost”, si nce air m a sses & m e t influences acting on the for m ation of ozone are lim ited prim a r ily to sunny summer days, while reactions of SOx and especially NOx are also im portant in clouds, at night, dur ing winter, etc.

P. 1-10, line 2: You need som e thing like “with” before “effects”.

P. 1-11, line 11: add “,” after “sediments”.

P. 1-12, line 3: Add som e thing like “Research on” before “E ffects”.

P. 1-12, line 7: Change “... and in the cas e of calcium , m a gnesium and potassium , are essential ... ” to som e thing like “... and b ecause calcium , m a gnesium and potassium are essential ... ”

P. 1-12, line 9: “correlated” is pretty wea k. Could m a ybe change it to “associated”.

P.1-12, lines 22 & 23: No idea what the poi nt is here, but I’m sure it’s not the “uncertain ties” that caus e gr eater relative contributions...

P. 1-12, line 24: I would change “... m a y be hi gher” to “can b e substan tially higher” (o f course episodic extrem es are higher than averages. Ain’t no “m ay” about it).

P. 1-12, line 25: You could delete “over-“ (or else delete “often”).

P. 1-13, lines 7-9: This obs ervation that form ation of a m m o niated nitrate & sulfate aerosols extends the atmospheric lifetim e (& tran sport) of NH3/4 from a day to m o re than a week (prior to deposition), helps illustrate the problem of avoidi ng discussion of sulfate & nitrate aerosols from t h is NAAQS Review process.

Chapter 4 P. 4-1, lines 3-4: As indicated elsew h ere, avoiding any “duplica ting” of topics intended to be addressed in the PM review doesn’t necessari ly save any staff res ources. A ‘portable’ section on the visibility eff ects of sulfate and n itrate aerosols could be cheaply “duplicated” and copy/pasted in both the SO2/ NOx ISA and the PM ISA. It would m a ke for som e interesting policy discussion (to incl ude either here or in PM IS A or both) to consider whether future visi bility m i ght be m o st efficiently improved by secondary PM2.5 standards or by alternative secondary in dicators for sulfur & nitrogen oxides and their transform a tion products. For exam ple, an indicator of total oxidized atm o spheric sulfur (S from SO2 + SO4) m i ght be wort h considering (and would likely correlate well with total S deposition), but m a y be precluded by this a priori decision to separate aerosol

40phase transform a tion products of S & N from their precursor gases and their deposition products.

P. 4-1 lines 9-12: This s e ntence n e eds work. If the subject is “cat egory”, the (line 9 ) verb (line 10) should be “is” not “are”, but how does this category get to be “these processes” (line 11), and what is it that “i nteracts” (line 12) w ith other PM components?

P. 4-3 line 8: W hy not include “and Ca nadian”, since their deposition is often predom inantly from US sources and we do have an AQ Agreem ent on acid deposition. Generally, I think th ere will be a v e ry usef ul body of historical and con t inuing recent literature relating to critical lo ads an d si m ilar approaches from both Canadian and European research groups – who are m o re gene r a lly m o re advanced in th is are a than we are. I t could be an espec i ally lim itin g approach to f o cus here prim arily o n US studies

.

P. 4-5, line 15: You could add “, transport” after “chem istry”

P. 4-5, line 48: Might add a bulle t o r two relatin g to the (tim e lags and ) p hysica l

, chem ical and ecological characteristics of “recovery” from acidification and how the end points m i ght dif f

e r f r om pre-a c idif ic a tion cond itio ns.

Chapter 5 P. 5-2, line 7: Might also consider including Southern Canada in som e of the US “m apping” exercis e s (for example for e st sensitivity and surface water m a pping by NE Governors & Eastern Canadian Prem iers).

P. 5-3, lines 10-20: In developing and co m p aring these gridded layers of a m bient concentration and deposition, it would be usef ul to include grid la yers aerosol SO4, NO3 & NH4 (reg a rdles s of whether v i sib i lity ef f

ect s a r e consid ere d here), and m i ght also be inform ative to include sim ilar gridded em ission data and analyses (i.e. plots of the ratios of

depositio n to em issions).

P. 5-3, line 29: Could add “current and historical” after “including”.

P. 5-3, line 32: Could add “, National Parks and Fish and Wildlife Refuges and National” between “Class I“ and “W ilderness”.

Chapter 6 P. 6-1, line 6-1: It’s very encouraging to see the option of a “tot al nitrogen” indicator (presum a bly to include deposition of all oxidized and reduced N). It’s no t clea r in ea rlier sections of the plan that this option is actua lly on the tab l e, an d that effects of NH3 & NH4 deposition will b e f u lly cons ide r ed. An inte resting rang e of other op tiona l indica tors (a nd recep tor-specific m odifiers) fo r b i ological s e n s itiv ity to fertiliz ation o r acidification also seem to be presented he re for the first tim e (as exclusively policy considerations). The technical foundations for use of these po tential indicators should be presented up front and in public in th e ISI and ev aluated in th e ecolog i cal risk as sessm ent – rather than considered onl y in the Agency’s internal policy assessm ent discussions.

41P. 6-2, line 8: I’m not sure that determ in ation of “adversity” is exclusively a policy decision. Many of the various tools and m e thods for assess ing adversity are developed and evalua te d in the s c ie ntif ic realm and associated literature (albe it the dism al science )

. Presentation of these technique s and their associated resu lt s s hould not be withheld un til the la st-m inute ANPR.

The concept of “sustaina b ility” is a r e lated topic which is a p o licy con s id eration tha t would benefit from advance scientific illu m i nation (in m i ght conceptually add a tim e dim e nsion to the concep t of “advers ity”). Are th ere eco system s where the presen t state of acidification is not currently resulting in “adve rse” eco logical effects, b u t where th e net rate of base cation rem oval from acid deposition can’t be sustained in the future?

42Comm ents from Mr. Da vid Shaw

I believe EP A’s Draft Plan fairly p r esents th e key policy-relevant i ssues and the proposed

m e thod to review issues related to science, risk-exposure and policy. The Draft Plan also recognizes the significant regional variability in effects associated with this issue.

The Draf t Plan sta t es th a t the role of ammoni a will be con s ide r ed as pa rt o f the analys is but does not contain spe c if ics on ho w the role of ammonia will b e evalu a ted. The lev e l of a m m onia em issions in the United States is substantial and in orde r to f u lly r e view th e secondary N AAQS for SO2 and NO2, its role in transport and subsequent deposition for m ation needs to be fully understood and evaluated.

Substantial data from current studies of various ecosystem s exists and should be used as part of this review. Current data shows s m all, but im proved trends in aquatic chem istry and species. A thorough analysis of these tre nds should be included in this review and factored into any m odeling provide d as part of E P A’s analysis.

43Comments from Dr. Kathleen Weathers

This draft plan is in places specific and in ot hers quite vague, necessa rily; it is a draft plan. Nonetheless, while some of the sections are ra ther straightforward and reasonably clear, the Risk/Exposure section is signifi cantly underdeveloped. It will be, ultimately, the synthesis of research findings and understanding. Thus, amon g other things, the develo pment of a conceptual model as well as clearly defini ng specific response variables w ill be critical to developing a credible analysis to supp ort this area of inquiry.

Below I have listed general as well as many specif ic comments on this version of the draft.

First, I am encouraged that in 1995 the Acid De position Standard Feasibility Report to Congress concluded that “establishing acid deposition standards for sulfur a nd nitrogen deposition may at some point in the future be technically feasible ...” The ability to relate emissions, deposition and ecosystem effects seems to me still at the core of the secondary effects assessment (see below).

A primary science and policy-relevant “tool” that was not explicitly addressed is the importance of the environmental monitoring data and programs that have been and will be necessary to detect long-term and short-term secondary e ffects of NOx and SOx. Ultimately, this document should identify what monitoring programs are nece ssary to determine the efficacy of air quality related policy.

I applaud the efforts to combine the effects of po llutants. That said, I think it very important to consider the emissions, deposition and ecosystem effects of ammonia and ammonium as well, as was pointed to in section 1.4.3. This review s hould continue to underscore the importance of linked biogeochemical processes in consider ing effects of NOx and SOx on ecosystems. Compartmentalizing analyses/assessment by chemical species or particle size makes little sense from an ecosystem effects standpoint.

Throughout (page 3-2 and beyond) the document, the importance of recep tor surfaces (i.e., landuse/landcover) in influencing atmospheri c deposition is under realized. “Ecosystem receptors” are considered important to identify fo r their susceptibility to SOx and NOx in this report, however, it is also important to recogni ze the importance of receptor surfaces in affecting the deposition of gases and particles (dry de position), since dry de position can contribute significantly to total deposition (in many lo cations and for many chemical species > 50% of total deposition).

Introduction: The relative influence of ground-based vs tall stack-emitted SOx and NOx vis-à-vis deposition should be noted.

The background (history) section is qu ite useful. Thank you for including it.Section 1: 1.4 Science Prim er line 21 : what’s th e def i nition of “gen erally acc epted scien c e ? ” By whom ? How is it de term ined?

line 31: ...”can initiate changes in...”

Figure 1.1 m i ght be m o dified for clarity. For exam ple, the use of the word “soil processes (e.g., nitrate, sulfate and NHx)” is c onfusing; processes with in the soil influence the rate of production

or m ove m e nt of these ions. The arrow showi ng dry deposition depositin g vertically to land surface could be m odified to indicate m o re real istic transfers (horizon tal d e position an d/or deposition to trees). It might al so be worth m odifying the size of the arrows (for fluxes) to indicate (broadly) propo rtional contribution.

1.4.1 The beginning of this section could be m a de clearer and m o r e linear.

1.4.3 I think it very important to include ammonia/ ammonium as part of discussion on nitrogen deposition, especially since it is becom i ng an increasing issu e in parts of the US (e.g., southeastern US). Salient points from the PM re view should be cross referenced in the NOx/SOx report, at a m i ni m u m.

Section 3: It is important that dry deposition is consid ered part of this review (the deposition of gases and particles).

Section 4: It would be helpful to include a list of the related topics that will be addressed by the PM science assessm ent, just for references.

Page 4-1. I a ssum e that the data f r om US and Canadian f e dera l m onitoring networks will b e used as a basis to help...”provide a bett er understanding of th e nature, sources, di stribution...” of air and precipitation chem istry and de position. If so, they should be not ed as a source of infor m ation in addition to peer r e vie w ed lite ratu r e

.

How will the vast litera t ure be dis t illed and/or w e ighted ?

Give dates f o r the window in which published l iterature will be cons idered (page 4-1).

Page 4-2: D e position (a tmospheric a nd acid depo sitio n ) shou ld be used as a sear ch te r m . Also, a brief accounting of the relative numbers of papers in each of the search categories would be instru ctive.

Page 4-3: I think the focus should be explicitly expanded to recent studies in the US and abroad, especially like ecosystem s in other count ries (C anada and the UK, for exam ple). It seem s to m e that the assessm ent of the scientif ic quality of studies is redundant, at best, with peer review and m a y lead to subjectivity and/or b i as in d ecid i ng which stu d ies are con s idered high quality and which are not.

45Section 5: T h is section’s title addresses exposure (oft en synonym ous with deposition, it appears) and risk. Th e title is inconsisten t with the discussion below and should more accu rately read : Exposure and Risk.

Page 5-1: T h e introductory paragraphs to this section are quite unclear. C r eating a conceptual model (i.e., figure) depicting the proposed steps of the assessm e nt would help. As I understand it, the goals are to consider the effects of nitrogen and sulfur deposition (aka inputs) to ecosystem s

. The response variables f o r ecosystem s are functi ons (such as productivity, rates of nutrient cycling), and the m o re general ability of the ecosystem to produce clean water/air (i.e., goods and services via the ecosystem functions noted above), and that these ecosystem functions and services will be valued.

I could not tell what long-term trends would be assessed (line 14), nor how such things as “biolog i cally-relevant” indices or “s ensitive” e c o system s will be def i ned

. Furtherm ore, in developing indices for assessm ent, it would be useful to know what scientific criteria are likely to be used by the Adm i nistrator when s/he m a kes “the final decision as to whether an effect is significan tly adverse, ” s o that this section can be m a de most useful and relevant to the process.

There is confusion throughout this section in regard to the use of the term s exposure (does this

m ean a m bie n t air concentrations of SOx a nd NOx and their effects on ecosystem s? ) and deposition, and the quantity of N and/or S deliv ered to ecosystem s. De m o nstrating the link between air concentratio ns and deposition is of cour se critical to both exposure and risk

assessm ents and is a topic that it bein g activ ely research ed.

Once again, the scope s e ction m i ght reiterate wh at the response variable s are. (Many of the potential questions to be posed are also active areas of research.)

The topic of ecological recovery is a challenge . F i rst, it m u st be defined—is it biological? chem ical? What are the m easures ? Recover to wh at? Next, in regard to assessing standards,

recovery m a y be especially relevant in regard to thresholds: are there dem onstrated exposures and levels of deposition beyond which ecologica l recovery can, or cannot, be achieved? Exam ining the litera ture f o r this coun try and ab ro ad on the determ ina tion of environmental thresho l ds for N and S deposition an d exposure will be importan t.

5.1 Assessment Approach The goals here, once again, are to exam ine the relationships between em ission and deposition, and deposition and ecosystem effects (this goal is stated in the Appendi ces, and see above). Thus, it seem s i m portant to be clear, from th e outset, about the suite of ecosystem effects (response variables) to be consid ered (see comm e n ts above). Als o, bringing to bear all of the data and analyses available, from pr ocess m odels as well as from monitoring program s and specific research pro j ects will be importan t , as s uggested. T h ere are pub lished s t udies for areas of the country showing relationships between em i ssions and air/rain concentrations and, in som e cases, wet deposition. As noted in this docum ent, deciding on the relevant tim e step for this analysis will be important. For example, is annua l or seasonal deposition sufficient to determ ine

46welfare effects, or are hourly or daily data necessary? For evaluating m a ny ecosystem responses, the form er m i ght be the focus.

How does the CMAQ model comp are to other es tim at es of total deposition based on monitoring data ? Does CMAQ take into ac coun t land us e/la nd cover ? D o regions of high and lo w depositio n line up, especially for sensitiv e ecos y st em s, using different approaches ?

Page 5-3, lines 10-20: It is unclear to m e what analyses ar e being proposed and how other data

m i ght be used in these analyses (e.g., pr ecipitation, relative hum i dity, etc.).

There exist GIS-based m a ps of sensitiv e ecosy s t em s as well as of atm o spheric d e pos ition (e.g., www.ecosystem s-research.com /fmi/r eports). Although I think that the idea of “norm a l i zing” ecosystem s is inte res ting, data f o r the types of characteristics iden tif ied a r e unlike l y to be widely available and/or published. It m a y be instructive to look at the BioScience articles on acid rain (2001) and nitrogen (2003) that ar e a result of the ScienceLinks pr ogram as m odels for synthesis.

Although the cluster analysis can group ecosystem s together based on certain charac teristics, I underscore that it is critical that those characte ristics are relevant to th e questions being asked. (I have seen the m e thod used in ways that are completely irrelevant to the process being addressed).

Models I think it importan t to preface a m o del resu lts or modeling secti on with a general discussion on the purpose, utility, strengths and li mitations of the m odels used as part of this analysis. Rather than being predictive, m o st m odels are best exercised as heuristic tools.

Also, there is no m e ntion of the potential use of Day-Cent-Chem except as part of a list. Further analysis of and emphasis on GIS-based m odels should be considered

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