# The Nature of the Fine Particle and Regional Haze A ir

Quality Problems in the MANE-VU Region: A Conceptual Description

Prepared for the Ozone Transport Commission

Prepared by NESCAUM Boston, MA

Final November 2, 2006

Contributing Authors

Tom Downs, Maine DEP Iyad Kheirbek, NESCAUM Gary Kleiman, NESCAUM Paul Miller, NESCAUM Leah Weiss, NESCAUMii



## Acknowledgements

NESCAUM thanks the U.S. EPA’s support of the Mid-At lantic/Northeast Visibility Union Regional Organization whose work has provided the foundational basis of this report.

NESCAUM also thanks the following people for their comments and input during the development of this report:

John Graham, NESCAUM Kurt Kebschull, Connecticut Department of Environme ntal Protection Tonalee Key, New Jersey Department of Environmental Protection Mohammed A. Majeed, Delaware Department of Natural Resources and Environmental
Conservation David Wackter, Connecticut Department of Environmen tal Protection Susan Wierman, MARAMA Mike Woodman, Maryland Department of the Environmen t Martha Webster, Maine Department of Environmental P rotection Jung-Hun Woo, NESCAUMiii 

### TABLE OF CONTENTS

Acknowledgements...................................

................................................... ....................... ii
Executive Summary..................................

................................................... ..................... vii

1. Introduction....................................

................................................... ......................... 1-1 1.1. Background....................................

................................................... ............... 1-1
1.2. PM Formation ..................................

................................................... ............. 1-2 1.3. PM Impacts on Visibility......................

................................................... ........ 1-3
1.4. PM 2.5 Design Values in the MANE-VU Region............... ............................... 1-5 1.5. Regional haze baseline conditions.............

................................................... ... 1-6

2. A Detailed Look at Fine Particle Pollution and R egional Haze in The MANE-VU Region.............................................

................................................... .............................. 2-1 2.1. Chemical composition of particulate matter in the rural MANE-VU region .. 2-1 2.2. Rural versus urban chemistry..................

................................................... ...... 2-3 2.3. Geographic considerations and attribution of P M 2.5 /haze contributors ........... 2-6 2.4. CAIR Modeling .................................

................................................... ......... 2-10
2.5. Seasonal differences..........................

................................................... .......... 2-12 2.6. Summary.......................................

................................................... .............. 2-17
3. MANE-VU Emission Inventory Characteristics for F ine Particles........................... 3-1 3.1. Emissions inventory characteristics...........

................................................... ... 3-1 3.1.1. Sulfur dioxide (SO 2 ) .................................................. .............................. 3-1 3.1.2. Volatile organic compounds (VOCs)........... ............................................ 3-3 3.1.3. Oxides of nitrogen (NO X ) .................................................. ...................... 3-4 3.1.4. Primary particulate matter (PM 10 and PM 2.5 )........................................... 3-6 3.1.5. Ammonia emissions (NH 3 ).................................................. .................. 3-10 3.2. Emissions inventory characteristics outside MA NE-VU .............................. 3-12

4. What will it take to clean the air? .............

................................................... .............. 4-2 4.1. Meteorological and Pollution Overview of Augus t 8-16, 2002....................... 4-2 4.2. Temporally and spatially resolved PM 2.5 measurements................................. 4-7 4.3. Implications for control strategies ...........

................................................... ... 4-10 4.4. Conclusion: Simplifying a complex problem ..... ........................................... 4-12
Appendix A: Excerpts from EPA Guidance Document, Gu idance on the Use of Models

and Other Analyses for Demonstrating Attainment of Air Quality Goals for Ozone, PM 2.5 , and Regional Haze
Appendix B: Monitoring Data from Class I sites in M ANE-VU
Appendix C: Additional Considerations for PM 2.5 Air Quality Managementiv 

### FIGURES

Figure 1-1. View of a good visibility day (left) a nd a poor visibility day (right) at Acadia National Park, Maine in June 2003..................

................................................... .. 1-3 Figure 1-2. Schematic of visibility impairment due to light scattering and absorption (adapted from Malm, 2000). .........................

................................................... ..... 1-4 Figure 2-1. Comparison of contributions during dif ferent seasons at Lye Brook Wilderness Area on 20% worst visibility (high PM 2.5 ) days (2000-2003). .......... 2-2 Figure 2-2. Comparison of species contributions on best and worst days at Lye Brook
Wilderness Area....................................

................................................... ............. 2-3 Figure 2-3. New York nonattainment area (Elizabeth , NJ) compared to an upwind background site (Chester, NJ)......................

................................................... ...... 2-5 Figure 2-4. Boston urban area (Boston, MA) compare d to an upwind background site (Quabbin Reservoir, MA) ............................

................................................... ...... 2-5 Figure 2-5. 2002 Seasonal average SO 4 based on IMPROVE and STN data................. 2-7 Figure 2-6. 2002 Annual average PM 2.5 , sulfate, nitrate and total carbon for MANE-VU based on IMPROVE (I) and STN (S) data. PM 2.5 mass data are supplemented by measurements from the FRM network (•).............. ............................................... 2-7 Figure 2-7. 2002 Annual average contribution to PM 2.5 sulfate as determined by multiple analysis methods for four Class I areas spanning MA NE-VU and Virginia ........ 2-9 Figure 2-8. 2002 Annual average mass contribution to PM 2.5 at Brigantine Wilderness in New Jersey (IMPROVE) and sulfate contributions as d etermined by tagged REMSAD model simulations (NESCAUM, 2006) ........... ................................. 2-10 Figure 2-9. Moving 60-day average of fine aerosol mass concentrations based on longterm data from two northeastern cities.............

................................................... 2-13 Figure 2-10. The 30-day average PM 2.5 concentrations from 8 northeastern cities during
2002...............................................

................................................... ................... 2-14 Figure 2-11. Mean hourly fine aerosol concentration s during 2002 summer months... 2-15 Figure 2-12. Mean hourly fine aerosol concentration s during 2002 winter months...... 2-15 Figure 2-13. Summertime at Mt. Washington ..........

................................................... .. 2-17 Figure 2-14. Wintertime in Boston ..................

................................................... ........... 2-17 Figure 3-1. State level sulfur dioxide emissions..

................................................... ........ 3-2 Figure 3-2. 2002 MANE-VU state SO 2 inventories ....................................... ................ 3-2 Figure 3-3. 2002 MANE-VU state VOC inventories ..... ................................................. 3- 4 Figure 3-4. State level nitrogen oxides emissions .

................................................... ...... 3-5 Figure 3-5. Plot of monitored NO X trends in MANE-VU during 1997-2005 ................ 3-5 Figure 3-6. 2002 MANE-VU state NO X inventories ....................................... ................ 3-6 Figure 3-7. State level primary PM 10 emissions ......................................... ..................... 3-8 Figure 3-8. State level primary PM 2.5 emissions ......................................... .................... 3-8 Figure 3-9. 2002 MANE-VU state primary PM 10 inventories........................................ . 3-9 Figure 3-10. 2002 MANE-VU state primary PM 2.5 inventories...................................... 3 -9 Figure 3-11. State level ammonia emissions .........

................................................... ..... 3-11 Figure 3-12. 2002 MANE-VU state NH 3 inventories....................................... ............. 3-11 Figure 4-1. Spatially interpolated maps of fine par ticle concentrations August 9 – 16,
2002...............................................

................................................... ..................... 4-4v

Figure 4-2. Surface weather maps for August 9-16, 2 002............................................... 4 -5 Figure 4-3. HYSPLIT 72-hour back trajectories for A ugust 9-16, 2002......................... 4-6 Figure 4-4. Hourly average fine aerosol at 8 sites during the August 2002 episode ....... 4-7 Figure 4-5. 24-hour rolling average fine aerosol a t 8 MANE-VU sites during the August 2002 episode .......................................

................................................... ............... 4-8 Figure 4-6. Composite images from NASA’s TERRA Sat ellite on August 13, 2002 showing fine particle pollution/haze. ..............

................................................... ... 4-9 Figure 4-7. NASA MODIS Terra Satellite Image, Back Trajectories and NO X Inventory

................................................... ................................................... ......................... 4-9 Figure B-1. Monitoring Data from Acadia NP, ME .... .................................................. B -2 Figure B-2. Monitoring Data from Brigantine, ME...

................................................... . B-3 Figure B-3. Monitoring Data from Great Gulf, NH...

................................................... . B-4 Figure B-4. Monitoring Data from Lye Brook, VT....

................................................... B-5 Figure B-5. Monitoring Data from Moosehorn, ME .... ................................................. B- 6 Figure B-6. Monitoring Data from Washington, DC... .................................................. B -7 Figure B-7. 20% Worst and Best 2000-2003 Visibilit y Days at Acadia NP, ME ......... B-8 Figure B-8. 20% Worst and Best 2000-2003 Visibilit y Days at Brigantine, NJ ........... B-9 Figure B-9. 20% Worst and Best 2000-2003 Visibilit y Days at Great Gulf, NH........ B-10 Figure B-10. 20% Worst and Best 2000-2003 Visibili ty Days at Lye Brook, VT ...... B-11 Figure B-11. 20% Worst and Best 2000-2003 Visibili ty Days at Moosehorn, ME .... B-12 Figure B-12. 20% Worst and Best 2000-2003 Visibili ty Days at Washington, D.C... B-13 Figure B-13. 20% Best 2000-2003 Visibility Days Sp eciated Contributions to Extinction

................................................... ................................................... ...................... B-14 Figure B-14. 20% Best 2000-2003 Visibility Days Sp eciated Contributions to Extinction

................................................... ................................................... ...................... B-15 Figure C-1. Effects of averaging times (or tempora l resolution) on time series
information........................................

................................................... ................ C-2 Figure C-2. Difference in FRM data between 10 urba n-rural site pairs for 2002 ......... C-4 Figure C-3. Regional PM 2.5 and NO X in 2002 ............................................ ................... C-6 Figure C-4. PM 2.5 vs. NO X correlation by season............................. ............................. C-6vi 

### TABLES

Table 1-1. 2004 PM 2.5 Design Value for Nonattainment Areas in MANE-VU ... .......... 1-6 Table 1-2. Fine mass and percent contribution for 20 percent worst days ..................... 1-7 Table 1-3. Fine mass and percent contribution for 20 percent best days........................ 1-7 Table 1-4. Particle extinction and percent contrib ution for 20 percent worst days ........ 1-8 Table 1-5. Particle extinction and percent contrib ution for 20 percent best days........... 1-8 Table 1-6. Natural background and baseline calcula tions for select Class I areas ......... 1-8 Table 2-1. Upwind states that make a significant c ontribution to PM 2.5 in each downwind nonattainment county (2001 modeling). .............. ............................................... 2-11
Table 2-2. Maximum downwind PM 2.5 contribution (μg/m 3 ) for each of the 37 upwind states (2001 data). ................................

................................................... ............ 2-11
Table 3-1. Eastern U.S. RPOs and their state membe rs................................................ 3 -12
Table 3-2. SO 2 emissions in eastern RPOs (tons/yr) ............... ..................................... 3-13
Table 3-3. NO X emissions in eastern RPOs (tons/yr) ............... .................................... 3-13 Table 3-4. VOC emissions in eastern RPOs (tons/yr) .................................................. 3 -13 Table C-1. MANE-VU urban-rural site pair informati on.............................................. C-3vii



## Executive Summary

Scientific evidence has established a solid link be tween cardiac and respiratory health risks and transient exposure to ambient fine particle pollution. The same fine particles that are capable of penetrating deep into the lungs are also in the size range that is most efficient at absorbing and scattering visib le light, thus impairing visibility. The emission sources, atmospheric chemistry, and meteor ological phenomena that influence ambient concentrations of fine particle pollution c an act on scales that range from hundreds to thousands of kilometers. Fine particles are not exclusively a secondary pollutant; primary fine particle pollution from loc al sources can have a significant effect on ambient concentrations in some locations. Fine p articles are also not exclusively a summertime pollutant. There are important differenc es between the meteorological and chemical dynamics that are responsible for high fin e particle levels during summer and
winter.
In 1997, the U.S. Environmental Protection Agency ( USEPA) issued a national ambient air quality standard (NAAQS) for fine parti cles with an aerodynamic diameter of 2.5 micrometers or less. In 1999, the USEPA follow ed up with the Regional Haze Rule that enforces a national visibility goal laid out i n the Clean Air Act. This will ultimately restore natural visibility to 156 national parks an d wilderness areas across the country (called “Class I” areas). To address these Clean A ir Act requirements, states will have to develop State Implementation Plans (SIPs) detailing their approaches for reducing fine particle pollution to meet the health-based fine pa rticle NAAQS. They also must develop plans that address the degradation of visibility th at exists in various parts of the Northeast (referred to as the Mid-Atlantic/Northeast Visibili ty Union (MANE-VU) region). As part of this process, the USEPA urges states to include in their SIPs a conceptual description of the pollution problem in their nonattainment and Class I areas. This document provides the conceptual description of the fine par ticulate and regional haze problems in the MANE-VU states consistent with the USEPA’s guid ance. Scientific studies of the regional fine particle pr oblem have uncovered a rich complexity in the interaction of meteorology and to pography with fine particle formation and transport. Large scale high pressure systems c overing hundreds of thousands of square miles are the source of classic severe fine particle episodes in the eastern United States, particularly in summer. These large, synop tic scale systems create particularly
favorable conditions for the oxidation of sulfur di oxide (SO 2 ) emissions to various forms of sulfate which, in turn, serves to form – or is i ncorporated into – fine particles that are subsequently transported over large distances. Th ese synoptic scale systems move from west to east across the United States, bringing air pollution emitted by large coal-fired power plants and other sources located outside MANE -VU into the region. This then adds to the pollution burden within MANE-VU on days when MANE-VU’s own air pollution sources are themselves contributing to po or air quality. At times, the high pressure systems may stall over the East for days, creating particularly intense fine particle episodes.
In the winter, temperature inversions occur that ar e effective at concentrating local primary particle emissions at the surface ove rnight and during early morning hours. This pollution can then be mixed into regionally tr ansported particle pollution (aloft) laterviii

in the morning when convection is restored. Additi onally, the lower temperature in the winter can shift the chemical equilibrium in the at mosphere slightly toward the production of nitrate particle pollution relative t o sulfate formation. As a result, nitrate can become a significant fraction of measured fine particle mass in parts of the eastern U.S. during winter months.
Primary and secondary emissions of carbon-containin g compounds (e.g., diesel exhaust, biogenic organic carbon emissions, and ant hropogenic volatile organic compound emissions) all contribute to a significant presence of carbonaceous aerosol across the MANE-VU region, which can vary from urba n to rural locations and on a seasonal basis. In addition, short range pollution transport exists, with primary and precursor particle pollutants pushed by land, sea, mountain, and valley breezes that can selectively affect relatively local areas. With th e knowledge of the different emission sources, transport scales, and seasonal meteorology in various locations adjacent to and within MANE-VU, a conceptual picture of fine partic le pollution and its impacts

emerges. The conceptual description that explains elevated r egional PM 2.5 peak concentrations in the summer differs significantly from that which explains the largely urban peaks observed during winter. On average, sum mertime concentrations of sulfate
in the northeastern United States are more than twi ce that of the next most important fine particle constituent, organic carbon (OC), and more than four times the combined concentration of nitrate and black carbon (BC) cons tituents. Episodes of high
summertime sulfate concentrations are consistent wi th stagnant meteorological flow conditions upwind of the MANE-VU region and the acc umulation of airborne sulfate (via atmospheric oxidation of SO 2 ) followed by long-range transport of sulfur emissions from industrialized areas within and outside the region.

National assessments have indicated that in the win ter, sulfate levels in urban areas are higher than background sulfate levels acr oss the eastern U.S., indicating that the
local urban contribution to wintertime sulfate leve ls is significant relative to the regional sulfate contribution from long-range transport. A n etwork analysis for the winter of 2002 suggests that the local enhancement of sulfate in u rban areas of the MANE-VU region ranges from 25 to 40% and that the long-range trans port component of PM 2.5 sulfate is
still the dominant contributor in most eastern citi es.
In the winter, urban OC and sulfate each account fo r about a third of the overall
PM 2.5 mass concentration observed in Philadelphia and Ne w York City. Nitrate also makes a significant contribution to urban PM 2.5 levels observed in the northeastern United States during the winter months. Wintertime concentrations of OC and nitrate in urban areas can be twice the average regional conce ntrations of these pollutants, indicating the importance of local source contribut ions. This is likely because winter
conditions are more conducive to the formation of l ocal inversion layers which prevent vertical mixing. Under these conditions, emissions from tailpipe, industrial and other
local sources become concentrated near the Earth’s surface, adding to background pollution levels associated with regionally transpo rted emissions.
From this conceptual description of fine particle p ollution formation and transport into and within MANE-VU, air quality planners need to develop an understanding ofix

what it will take to clean the air in the MANE-VU r egion. Every air pollution episode is unique in its specific details. The relative influ ences of the transport pathways and local emissions vary by hour, day, and season. The small er scale weather patterns that affect pollution accumulation and its transport underscore the importance of local (in-state)
controls for SO 2 , nitrogen oxides (NO X ) and volatile organic compound (VOC) emissions. Larger synoptic scale weather patterns, and pollution patterns associated with them, support the need for SO 2 and NO X controls across the broader eastern United
States. Studies and characterizations of nocturnal low level jets also support the need for local and regional controls on SO 2 and NO X sources as locally generated and transported pollution can both be entrained in low level jets f ormed during nighttime hours. The presence of land, sea, mountain, and valley breezes indicate that there are unique aspects of pollution accumulation and transport that are ar ea-specific and will warrant policy responses at the local and regional levels beyond a one-size-fits-all approach.
The mix of emission controls is also important. Re gional fine particle formation is primarily due to SO 2 , but NO X is also important because of its influence on the chemical equilibrium between sulfate and nitrate po llution during winter. While the effect of reductions in anthropogenic VOCs is less well characterized at this time, secondary organic aerosol (SOA) is a major componen t of fine particles in the region and reductions in anthropogenic sources of OC may have a significant effect on fine particle levels in urban nonattainment areas. Therefore, a combination of localized NO X and
VOC reductions in urban centers with additional SO 2 and NO X reductions from across a larger region will help to reduce fine particles an d precursor pollutants in nonattainment areas as well improve visibility across the entire MANE-VU region.PM 2.5 and Regional Haze Air Quality Problems in the MANE -VU Region: A Conceptual Description Page 1-1



## 1. INTRODUCTION

1.1. Background
Fine particle pollution is a persistent public heal th problem in the MidAtlantic/Northeast Visibility Union (MANE-VU) regio n. Because of its physical structure, fine particulate matter (PM 2.5 ) can bypass conductive airways and deliver exogenous materials, such as reactive organic chemi cals that adsorb onto the particle core, into the deep lung. 1 Studies of particulate matter (PM) in urban areas have found associations of short- (daily) and long-term (annua l and multiyear) exposure to airborne
PM as well as PM 2.5 with cardiopulmonary health outcomes. These effect s include increased symptoms, hospital admissions and emergen cy room visits, and premature death (Pope et al. 2004).
In addition to health implications, visibility impa irment in the eastern United States is largely due to the presence of light-abso rbing and light-scattering fine particles in the atmosphere. The United States Environmental Protection Agency (USEPA) has identified visibility impairment as the best unders tood of all environmental effects of air pollution (Watson, 2002). A long-established physi cal and chemical theory relates the interaction of particles and gases in the atmospher e with the transmission of visual information along a sight path from object to obser ver. The Clean Air Act requires states that have areas d esignated “nonattainment” of the fine particle national ambient air quality stan dard (NAAQS) to submit State Implementation Plans (SIPs) demonstrating how they plan to attain the fine particle NAAQS. 2 The Clean Air Act also contains provisions for th e restoration and maintenance of visibility in 156 federal Class I ar eas. 3 SIPs for dealing with visibility impairment (or regional haze) must include a long-t erm emissions management strategy aimed at reducing fine particle pollution in these rural areas.
As part of the SIP process for both of these air qu ality issues, the USEPA urges states to include a conceptual description of the p ollution problem. The USEPA has provided guidance on developing a conceptual descri ption, which is contained in Chapter 11 of the document “Guidance on the Use of Models and Other Analyses for

1 PM 2.5 or “fine particles” refer to those particles with a diameter ≤ 2.5 micrometers ( μ m).

2 The 1997 PM 2.5 NAAQS includes a requirement that the three-year average of y early annual average
PM 2.5 design values must be below 15 μg/m 3 and a requirement that the three-year average of the 98 th percentile 24-hour average concentration must be below 65 μg/ m 3 . In October 2006, the USEPA acted to change the daily standard (98 th percentile value based on valid 24-hour average concentratio ns measured at a site) from 65 to 35 μg/m 3

. 3 The Class I designation applies to national parks exceeding 6,000 acres, wilderness areas and national memorial parks exceeding 5,000 acres, and all international par ks that were in existence prior to 1977. In the MANE-VU area, this includes: Acadia National Park, Maine; Brigantine Wilderness (within the Edwin B. Forsythe National Wildlife Refuge), New Jersey; Great Gul f Wilderness, New Hampshire; Lye Brook Wilderness, Vermont; Moosehorn Wilderness (within the Mo osehorn National Wildlife Refuge), Maine; Presidential Range – Dry River Wilderness, New Hampshire; an d Roosevelt Campobello International Park, New Brunswick.PM 2.5 and Regional Haze Air Quality Problems in the MANE -VU Region: A Conceptual Description Page 1-2

Demonstrating Attainment of Air Quality Goals for O zone, PM 2.5 , and Regional Haze” (EPA-Draft 3.2, September 2006) (Appendix A of this report reproduces Chapter 11 of the USEPA guidance document). This report provides the MANE-VU states with the basis for their conceptual descriptions, consistent with the USEPA’s guidance. In the guidance, the USEPA recommends addressing 13 questi ons related to PM 2.5 and eight questions related to visibility to help define the problem in a nonattainment or Class I area. This report addresses these questions, as wel l as provides some in-depth data and analyses that can assist states in developing conce ptual descriptions tailored to their specific areas.



### 1.2. PM Formation
Fine particles directly emitted into the atmosphere are called “primary” fine particles, and they come from both natural and huma n sources. These fine particles commonly include unburned carbon particles directly emitted from high-energy processes such as combustion, and particles emitted as combustion-related vapors that condense within seconds of being exhausted to ambie nt air. Combustion sources include motor vehicles, power generation facilities, indust rial facilities, residential wood burning, agricultural burning, and forest fires.
Fine particles are also comprised of “secondary” fi ne particles, which are formed from precursor gases reacting in the atmosphere or through the addition of PM to preexisting particles. Although direct nucleation from the gas phase is a contributing factor, most secondary material accumulates on pre-existing particles in the 0.1 to 1.0 micrometer (μm) range and typically account for a significant fraction of the fine PM mass. Examples of secondary particle formation incl ude the conversion of sulfur dioxide (SO 2 ) to sulfuric acid (H 2 SO 4 ) droplets that further react with ammonia (NH 3 ) to form various sulfate particles (e.g., ammonium sulfate ( NH 4 ) 2 SO 4 , ammonium bisulfate (NH 4 HSO 4 ), and letovicite ((NH 4 ) 3 H(SO 4 ) 2 ). The dominant source of SO 2 emissions in the eastern U.S. is fossil fuel combustion, primari ly at coal-fired power plants and industrial boilers. Similarly, secondary PM 2.5 is created by the conversion of nitrogen dioxide (NO 2 ) to nitric acid (HNO 3 ) which reacts further with ammonia to form ammonium nitrate (NH 4 NO 3 ) particles. Nitrate particles are formed from the NO X emitted by power plants, automobiles, industrial bo ilers, and other combustion sources. Nitrate production in the northeastern U.S. is ammo nia-limited and controlled by the availability of sulfate and temperature, especially along the East Coast. 4 While human sources account for most nitrate precursors in the atmosphere, there are some natural sources, including lightning, biological and abiolo gical processes in soils, and stratospheric intrusion. Large sources of ammonia a rise from major livestock production and fertilizer application throughout the Midwest, Gulf Coast, mid-Atlantic, and southeastern United States, in addition to the sour ces of ammonia associated with human
activities.
The carbon fraction of fine PM may refer to black c arbon (BC) and primary organic and/or secondary organic carbon (OC). Most black carbon is primary, which is

4 Ammonia reacts preferentially with sulfuric acid, and if sufficient excess ammonia is available, it can then combine with nitric acid to form particulate nitrate.PM 2.5 and Regional Haze Air Quality Problems in the MANE -VU Region: A Conceptual Description Page 1-3

also sometimes referred to as elemental carbon (EC) or soot. Black carbon is the lightabsorbing carbonaceous material in atmospheric part icles caused by the combustion of diesel, wood, and other fuels. Organic carbon inclu des both primary emissions and secondary organic PM in the atmosphere. Secondary o rganic particles are formed by reactions involving volatile organic compounds (VOC s), which yield compounds with low saturation vapor pressures that nucleate or con dense on existing particles at ambient temperature. Organic carbon in both the gas and sol id phase is emitted by automobiles, trucks, and industrial processes, as well as by man y types of vegetation. The relative amounts of organic carbon from different sources re main highly uncertain, and data are
needed to be able to assess the relative contributi on of primary versus secondary and anthropogenic versus biogenic production.



### 1.3. PM Impacts on Visibility
Under natural atmospheric conditions, the view in t he eastern United States would extend about 60 to 80 miles (100 to 130 kilometers) (Malm, 2000). Unfortunately, views of such clarity have become a rare occurrence in th e East. As a result of man-made pollution, the average visual range in the eastern half of the country has diminished to about 15-30 miles, approximately one-third the visu al range that would be observed under unpolluted natural conditions.
In general, the ability to see distant features in a scenic vista is determined less by the amount of light reaching the observer than by t he contrast between those features and their surroundings. For example, the illumination of a light bulb in a greenhouse is barely discernible on a sunny day but would be high ly visible at night. Similarly, a mountain peak is easily seen if it appears relative ly dark against the sunlit sky. If, on the other hand, a milky haze “fills” the space between the observer and the mountain peak, the contrast between the mountain and its backgroun d is diminished as both take on a similar hue (Figure 1-1).

Figure 1-1. View of a good visibility day (left) a nd a poor visibility day (right) at

Acadia National Park, Maine in June 2003.

Source: CAMNET, http://www.hazecam.net

In simple terms, this hazy effect occurs when small particles and certain gaseous molecules in the atmosphere absorb or scatter visib le light, thereby reducing the amount
of visual “information” that reaches the observer. This occurs to some extent even under natural conditions, primarily as a result of the li ght scattering effect of individual airPM 2.5 and Regional Haze Air Quality Problems in the MANE -VU Region: A Conceptual Description Page 1-4

molecules (known as Rayleigh scattering 5 ) and of naturally occurring aerosols. 6 The substantial visibility impairment caused by manmade pollution, however, is almost entirely attributable to the increased presence of fine particles in the atmosphere. 7

Figure 1-2 presents a simplified schematic of the w ay such small particles interact with packets of light or “photons” as they travel f rom a distant object to an observer. Along the way, particles suspended in the air can d eflect or scatter some of the photons out of the sight path. Intervening particles can a lso absorb photons, similarly removing them from the total amount of light reaching the ob server.

5 Because air molecules more effectively scatter light of short wavel engths (i.e., blue light), Rayleigh scattering explains the blue color of the sky.

6 Atmospheric aerosol is a more general term for fine parti cles suspended in the atmosphere and refers to any particle (solid or liquid) that is suspended in the at mosphere.
7 The only light-absorbing gaseous pollutant present in the atmosphere at significant conce ntrations is nitrogen dioxide (NO 2 ). However, the contribution of NO 2 to overall visibility impacts in the Northeast is negligible and hence its effects are not generally included in this discussion or in standard calculations of visibility impairment. Figure 1-2. Schematic of visibility impairment due to light scattering

and absorption (adapted from Malm, 2000).

Light from clouds scattered into sight path

Sunlight

scattered

Light reflected from ground scattered into sight path Light absorbed

Image-forming light scattered out of sight pathPM 2.5 and Regional Haze Air Quality Problems in the MANE -VU Region: A Conceptual Description Page 1-5

At the same time, particles in the air can scatter light into the sight path, further diminishing the quality of the view. The extraneou s light can include direct sunlight and light reflected off the ground or from clouds. Bec ause it is not coming directly from the scenic element, this light contains no visual infor mation about that element. When the combination of light absorption and light scatterin g (both into and out of the sight path) occurs in many directions due to the ubiquitous pre sence of small particles in the atmosphere, the result is commonly described as “ha ze.”



### 1.4. PM 2.5 

### Design Values in the MANE-VU Region
SIP developers use monitoring data in several impor tant ways to support SIP activities. This section as well as Section 1.5 pr esent measurements from the FRM and IMPROVE network needed in establishing SIP requirem ents. Following USEPA guidance (40CFR Part 50, Appendix N; USEPA, 2003a; USEPA, 2003b), we use these data to preview the Design Values and Baseline Cond itions that SIP developers must
consider for each nonattainment area and Class I ar ea. The current annual fine particle National Ambient A ir Quality Standard was
established in 1997 at 15 μ g/m 3 . To meet this standard, the 3-year average of a s ite’s annual mean concentration must not be greater than this level. The current daily standard
was set at 65 μ g/m 3 at the 98 th percentile level. To meet this standard, the 98 th percentile value (of valid measurements recorded at a site) mu st not be greater than this level. No counties in MANE-VU have been designated nonattainm ent for the daily standard, however, the USEPA has revised the NAAQS with respe ct to the 24-hr average concentrations and states will have to comply with the new standard (35 μ g/m 3 at the 98 th percentile level) within five years of designations (expected in 2010). Fine particle data from the USEPA’s Air Quality System (AQS) database for years 2002 through 2004
were used to determine the attainment status of mon itoring sites in MANE-VU.
Table 1-1 shows a summary of areas found to exceed the annual standard (no areas exceed the daily standard). As tabulated, 12 areas fail to achieve the annual standard, with design values ranging from 15.1 to 2 0.4 μ g/m 3 . The nonattainment areas are concentrated in Pennsylvania and the coastal ur ban corridor. Sulfates and organic carbon represent the largest contributors to these high fine particle levels.PM 2.5 and Regional Haze Air Quality Problems in the MANE -VU Region: A Conceptual Description Page 1-6

Table 1-1. 2004 PM 2.5 Design Value for Nonattainment Areas in MANE-VU

State(s) Nonattainment Area 2004 Annual Design Value 2004 24-hr

Design Value

MD Baltimore 16.3 41
PA Harrisburg-Lebanon-Carlisle 15.4 41

PA Johnstown 15.3 40

PA Lancaster 16.8 42
PA Liberty-Clairton 20.4 65
MD Martinsburg, WV-Hagerstown 16.1 39
NY-NJ-CT New York-N. New Jersey-Long Island 16.8 50
PA-NJ-DE Philadelphia-Wilmington 15.4 39
PA Pittsburgh-Beaver Valley 16.5 45
PA Reading 16.1 42
DC-MD-VA Washington, DC 15.1 42

PA York 16.9 43



### 1.5. Regional haze baseline conditions
The Regional Haze Rule requires states and tribes t o submit plans that include
calculations of current and estimated baseline and natural visibility conditions. They will use monitoring data from the IMPROVE program as the basis for these calculations. Table 1-2 and Table 1-3 present the five-year avera ge 8 of the 20 percent worst day mass concentrations and 20 percent best day mass concent rations respectively in six Class I
areas. Five of these areas are in MANE-VU and one (Shenandoah) is nearby but located in a neighboring regional planning organization (RP O) region. 9 Table 1-4 and Table 1-5 give the corresponding worst day and best day contr ibutions to particle extinction for the
six Class I areas. Each of these tables show the r elative percent contribution for all six Class I sites. Sulfate and organic carbon dominate the fine mass, with sulfate even more important to particle extinction.
To guide the states in calculating baseline values of reconstructed extinction and for estimating natural visibility conditions, the U SEPA released two documents in the fall of 2003 outlining recommended procedures (USEPA 200 3a; USEPA 2003b). Recently, the IMPROVE Steering Committee endorsed an alternat ive method for the calculation of
these values. The IMPROVE alternative methods were used, to create Table 1-6, which provides detail on the uniform visibility goals for the 20 percent worst conditions at the
six Class 1 areas.

8 Great Gulf calculations are based on four years of data (2001-2 004).

9 Note that values presented for Shenandoah, a Class I area in t he Visibility Improvement State and Tribal Association of the Southeast (VISTAS) region, are for com parative purposes only. VISTAS will determine uniform rates of progress for areas within its region.PM 2.5 and Regional Haze Air Quality Problems in the MANE -VU Region: A Conceptual Description Page 1-7

The first column of data in Table 1-6 gives the alt ernative proposed natural background levels for the worst visibility days at these six sites. MANE-VU has decided to use this approach, at least initially, for 2008 SIP planning purposes (NESCAUM, 2006). The second column shows the baseline visibi lity conditions on the 20 percent worst visibility days. These values are based on IM PROVE data from the official fiveyear baseline period (2000-2004) and again were cal culated using the IMPROVE alternative approach. Using these baseline and nat ural background estimates, we derive the uniform rate of progress shown in the third col umn. 10 The final column displays the interim 2018 progress goal based on 14 years of imp rovement at the uniform rate.

Table 1-2. Fine mass and percent contribution for 20 percent worst days

20% Worst-day Fine Mass ( μ g/m 3 )/% contribution to fine mass

Site SO 4 NO 3 OC EC Soil

Acadia 6.3/ 56% 0.8/ 7% 3.2/ 28% 0.4/ 4% 0.5/ 5% Brigantine 11.6/ 56% 1.7/ 8% 5.8/ 28% 0.7/ 3% 1/ 5%

Great Gulf 7.3/ 59% 0.4/ 3% 3.8/ 31% 0.4/ 3% 0.6/ 5% Lye Brook 8.5/ 58% 1.1/ 7% 3.9/ 27% 0.5/ 3% 0.6/ 4%

Moosehorn 5.7/ 54% 0.7/ 7% 3.4/ 32% 0.4/ 4% 0.4/ 4%

Shenandoah 13.2/ 68% 0.7/ 3% 4.2/ 22% 0.6/ 3% 0.7/ 4%

Table 1-3. Fine mass and percent contribution for 20 percent best days

20% Best-day Fine Mass ( μ g/m 3 )/% contribution to fine mass

Site SO 4 NO 3 OC EC Soil

Acadia 0.8/ 42% 0.1/ 6% 0.8/ 41% 0.1/ 5% 0.1/ 6% Brigantine 1.8/ 43% 0.5/ 11% 1.5/ 35% 0.2/ 6% 0.2/ 5%

Great Gulf 0.7/ 43% 0.1/ 7% 0.7/ 40% 0.1/ 5% 0.1/ 6% Lye Brook 0.6/ 44% 0.1/ 11% 0.4/ 33% 0.1/ 5% 0.1/ 7%

Moosehorn 0.8/ 37% 0.1/ 6% 1/ 47% 0.1/ 5% 0.1/ 5%

Shenandoah 1.4/ 45% 0.5/ 16% 1/ 29% 0.2/ 5% 0.2/ 5%

10 We calculate the rate of progress as (baseline – natural backgrou nd)/60 to yield the annual deciview (dv) improvement needed to reach natural background conditions in 2064, starting from the 2004 baseline.PM 2.5 and Regional Haze Air Quality Problems in the MANE -VU Region: A Conceptual Description Page 1-8

Table 1-4. Particle extinction and percent contrib ution for 20 percent worst days

20% Worst-day particle extinction (Mm -1 ) /% Contribution to particle extinction

Site SO 4 NO 3 OC EC Soil CM

Acadia 69.2/ 64% 8/ 7% 11.2/ 10% 4.3/ 4% 0.5/ 0% 1.9/ 2% Brigantine 127.1/ 66% 15.7/ 8% 24.2/ 13% 7/ 4% 1/ 1% 5.4/ 3%

Great Gulf 76.6/ 68% 3/ 3% 14.4/ 13% 3.9/ 3% 0.6/ 1% 3/ 3% Lye Brook 87.3/ 67% 9.1/ 7% 15.3/ 12% 4.8/ 4% 0.6/ 0% 1.8/ 2%

Moosehorn 58.5/ 60% 6.4/ 7% 11.9/ 12% 4.4/ 5% 0.4/ 0% 2.1/ 3%

Shenandoah 155.5/ 79% 5.8/ 3% 16.1/ 8% 5.7/ 3% 0.7/ 0% 2.5/ 1%

Table 1-5. Particle extinction and percent contrib ution for 20 percent best days

20% Best-day particle extinction (Mm -1 ) /% Contribution to particle extinction

Site SO 4 NO 3 OC EC Soil CM

Acadia 6.8/ 28% 1.1/ 4% 2.2/ 9% 0.9/ 4% 0.1/ 0% 0.7/ 6% Brigantine 14.8/ 35% 3.9/ 9% 4.5/ 11% 2.4/ 6% 0.2/ 1% 3.2/ 11%

Great Gulf 5.8/ 27% 1/ 4% 2/ 9% 0.8/ 4% 0.1/ 0% 0.9/ 8% Lye Brook 4.4/ 23% 1.2/ 6% 1.3/ 7% 0.6/ 3% 0.1/ 0% 0.5/ 6%

Moosehorn 6.7/ 26% 1.1/ 4% 3.1/ 12% 1/ 4% 0.1/ 0% 1.1/ 8%

Shenandoah 11.2/ 36% 4.2/ 13% 2.9/ 9% 1.6/ 5% 0.2/ 1% 1.1/ 5%

Table 1-6. Natural background and baseline calcula tions for select Class I areas

Site 20 % Worst

Days Natural Background (dv) 20% Worst

Days Baseline
2000- 04(dv) Uniform

Rate (dv/yr) Interim

Progress Goal 2018 (dv) 20% Best

Days Baseline 2000-04(dv)

Acadia 12.54 22.89 0.17 20.47 8.77 Brigantine 12.34 29.01 0.28 25.12 14.33

Great Gulf 12.12 22.82 0.18 20.32 7.66 Lye Brook 11.85 24.44 0.21 21.50 6.37

Moosehorn 12.10 21.72 0.16 19.48 9.15 Dolly Sods 10.45 29.05 0.31 24.71 12.28

James River Face 11.20 29.12 0.30 24.94 14.21

Shenandoah 11.44 29.31 0.30 25.14 10.92PM 2.5 and Regional Haze Air Quality Problems in the MANE -VU Region: A Conceptual Description Page 1-9

As demonstrated in Table 1-2, the inorganic constit uents of fine particles, sulfates
and nitrates are the dominant contributors to visib ility impairment, accounting for about 80 percent of total particle extinction. Within th e MANE-VU sites, the relative split between these two components is ~8 to 1 sulfate to n itrate (at Shenandoah, the average 20 percent worst day contribution of sulfates is ev en more dominant). Carbonaceous components account for the bulk of the remaining pa rticle extinction, ranging from 12 to nearly 20 percent, mostly in the form of organic ca rbon. The remaining components add little to the extinction budget on the worst days, with a few percent attributable to coarse mass and around a half percent from fine soil.PM 2.5 and Regional Haze Air Quality Problems in the MANE -VU Region: A Conceptual Description Page 1-10



### References

NESCAUM, Baseline and Natural Background Visibility Conditio ns: Considerations and Proposed Approach to the calculation of Baselin e and Natural Background Visibility Conditions at MANE-VU Class I areas , Northeast States for Coordinated Air Use Management, Boston, MA, June 2006.

Pope C.A., R.T. Burnett, G.D. Thurston, et al. “Car diovascular mortality and long-term exposure to particulate air pollution: epidemiologi cal evidence of general pathophysiological pathways of disease.” Circulation 109:71-7, 2004.

Malm, W.C., Introduction to Visibility , Cooperative Institute for Research in the Atmosphere (CIRA), Colorado State University, Fort Collins, CO, 80523, 2000.

Watson, J., “Visibility: Science and Regulation”, JAWMA 52:628-713, 2002.

USEPA, “Guidance for Tracking Progress under the Re gional Haze Rule” EPA-454/B03-004 September 2003a.
USEPA, “Guidance for Estimating Natural Visibility Conditions under the Regional Haze Program” EPA-454/B-03-005 September 2003b.

USEPA. “Guidance on the Use of Models and Other Ana lyses for Demonstrating Attainment of Air Quality Goals for Ozone, PM 2.5 , and Regional Haze.” U.S. Environmental Protection Agency Office of Air Quali ty Planning and Standards Emissions, Monitoring, and Analysis Division. Draf t 3.2- September 2006PM 2.5 and Regional Haze Air Quality Problems in the MANE -VU Region: A Conceptual Description Page 2-1



## 2. A DETAILED LOOK AT FINE PARTICLE POLLUTION AND REGIONAL HAZE IN THE MANE-VU REGION

Developing a conceptual description of fine particl e pollution or regional haze requires combining experience and atmospheric-scien ce expertise with multiple data sources and analysis techniques. This includes meas ured data on ambient pollutant concentrations as well as emission inventory and me teorological data, chemical transport modeling, and observationally based models (NARSTO, 2003). Here, we begin with a conceptual description based on the existing scient ific literature and regional data analyses concerning PM 2.5 and its effect on visibility. This includes numero us review articles and reports on the subject. Subsequent c hapters review monitoring data, emissions inventory information, and modeling resul ts to support the conceptual understanding of regional fine particle pollution p resented here.
Most past assessments of fine particle pollution an d visibility impairment have tended to be national in scope. For purposes of thi s discussion, we have selectively reviewed the literature in order to present a disti nctly eastern U.S. focus. While we already know much about fine particle pollution and visibility impairment and their causes in the MANE-VU region (see NESCAUM, 2001, 20 06; NARSTO, 2003; Watson, 2002), significant gaps in understanding remain wit h respect to the nitrate and organic component of PM 2.5 . While research continues, we have assembled the relevant information that is available to provide an overvie w of our current understanding of the regional context for PM 2.5 nonattainment and visibility impairment in the MAN E-VU region.



### 2.1. Chemical composition of particulate matter in the r ural MANEVU region
Sulfate alone accounts for anywhere from one-half t o two-thirds of total fine particle mass on high PM 2.5 days in rural areas of MANE-VU. Even on low PM 2.5 days, sulfate generally accounts for the largest fraction (40 percent or more) of total fine particle mass in the region (NESCAUM, 2001, 2004b). Sulfate accounts for a major
fraction of PM 2.5 , not only in the Northeast but across the eastern United States (NARSTO, 2003).
After sulfate, organic carbon (OC) consistently acc ounts for the next largest fraction of total fine particle mass. Its contribut ion typically ranges from 20 to 30 percent of total fine particle mass on the days with the hi ghest levels of PM 2.5 . The fact that the contribution from organic carbon can be as high as 40 percent at the more rural sites on
low PM 2.5 days is likely indicative of the role played by or ganic emissions from vegetation (so-called “biogenic hydrocarbons”).
Relative contributions to overall fine particle mas s from nitrate (NO 3 ), elemental carbon, and fine soil are all smaller (typically un der 10 percent), but the relative ordering among the three species varies with location and se ason. Figure 2-1 below, reflects the difference between nitrate and organic contribution s to rural fine particle concentrations during different seasons (monitoring data for addit ional sites in the MANE-VU region are in Appendix B).PM 2.5 and Regional Haze Air Quality Problems in the MANE -VU Region: A Conceptual Description Page 2-2

Figure 2-1. Comparison of contributions during dif ferent seasons at Lye Brook Wilderness Area on 20% worst visibility (high PM 2.5 ) days (2000-2003).

Almost all particle sulfate originates from sulfur dioxide (SO 2 ) oxidation and typically associates with ammonium (NH 4 ) in the form of ammonium sulfate ((NH 4 ) 2 SO 4 ). Ninety-five percent of SO 2 emissions are from anthropogenic sources (primarily from fossil fuel combustion), while the majority of ammonium comes from agricultural activities and, to a lesser extent, fr om transportation sources in some areas (NARSTO, 2003).
Two major chemical pathways produce sulfate from SO 2 in the atmosphere. In the gas phase, production of sulfate involves the o xidation of SO 2 to sulfuric acid (H 2 SO 4 ), ammonium bisulfate (NH 4 HSO 4 ), or ammonium sulfate, depending on the availability of ammonia (NH 3 ). In the presence of small wet particles (typical ly much, much smaller than rain drops or even fog), a highly efficient aqueous phase process can
oxidize SO 2 to sulfate extremely quickly (~10 percent per hour)

. Not only is sulfate the dominant contributor to fin e particle mass in the region, it accounts for anywhere from 60 percent to almost 80 percent of the difference between fine particle concentrations and extinction on the lowest and highest mass days at rural
locations in the northeast and mid-Atlantic states (See Figure 2-2). Notably, at urban locations such as Washington DC, sulfate accounts f or only about 40 percent of the difference in average fine particle concentrations for the 20 percent most versus least visibility impaired days (NESCAUM, 2001). 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110

Sulfate Nitrate Org Carbon Elem Carbon Soil Coarse MassExtinction (Mm-1) Winter - 12 days

Summer - 37 days

Spring - 17 days

Fall - 23 daysPM 2.5 and Regional Haze Air Quality Problems in the MANE -VU Region: A Conceptual Description Page 2-3

Figure 2-2. Comparison of species contributions on best and worst days

at Lye Brook Wilderness Area.



### 2.2. Rural versus urban chemistry
Contributions to fine particle mass concentrations at rural locations include longrange pollutant transport as well as non-anthropoge nic background contributions. Urban areas generally show mean PM 2.5 levels exceeding those at nearby rural sites. In t he Northeast, this difference implies that local urban contributions are roughly 25 percent of the annual mean urban concentrations, with regional aerosol contributing the remaining, and larger, portion (NARSTO, 2003).
This rural versus urban difference in typical conce ntrations also emerges in a source apportionment analysis of fine particle poll ution in Philadelphia (see Chapter 10 of NARSTO, 2003) using two different mathematical m odels, UNMIX and Positive Matrix Factorization (PMF). This analysis provid es additional insight concerning sources of fine particle pollution in urban areas o f the densely populated coastal corridor between Washington DC and New England. Specifically , this analysis found the following apportionment of PM 2.5 mass in the study area:

• Local SO 2 and sulfate: ~ 10 percent

• Regional sulfate: ~ 50 percent

• Residual oil: 4-8 percent

• Soil: 6-7 percent

• Motor vehicles: 25-30 percent

The analysis does not account for biogenic sources, which most likely are embedded in the motor vehicle fraction (NARSTO, 200 3). The Philadelphia study suggests that both local pollution from nearby sour ces and transported “regional”PM 2.5 and Regional Haze Air Quality Problems in the MANE -VU Region: A Conceptual Description Page 2-4

pollution from distant sources contribute to the hi gh sulfate concentrations observed in urban locations along the East Coast on an annual a verage basis. Summertime sulfate and organic carbon are strongly regional in eastern North America. Typically 75–95 percent of the urban sulfate concentrations and 60– 75 percent of the urban OC concentrations arise from cumulative region-wide co ntributions (NARSTO, 2003). Urban air pollutants are essentially added on top of this regional background. Nitrate plays a noticeably more important role at urban sites compa red to northeastern and mid-Atlantic rural monitoring sites, perhaps reflecting a greate r contribution from vehicles and other urban pollution sources (NESCAUM, 2001).
It is difficult to discern any significant meaning about the cause of “excess” mass from a single pair of sites. There are many factor s that influence the concentrations at a particular site and it is likely that for every pai r of sites that shows an urban excess, one could find some pair of locations that might show s omething similar to an urban “deficit.” While paired sites from an urban and a rural location will typically show greater concentrations in the urban location and lo wer levels of pollution in rural areas, great care must be exercised in the interpretation of any two-site analysis such as the comparisons of speciated components of PM 2.5 presented here. Nonetheless, such comparisons do provide a general feel for the typic al chemical composition of PM 2.5 in
the eastern U.S. and the relative differences in ch emical composition between rural and more urban locations. More detailed, “network”-wid e analyses (e.g., see NESCAUM 2004b; relevant sections are attached in Appendix C to this report) indicate that the results provided are not anomalous of typical urban environments in the MANE-VU region.
Figure 2-3 and Figure 2-4 compare two urban-rural p airs of speciation monitors: the New York nonattainment area (Elizabeth and Ches ter, New Jersey) and the Boston metropolitan area (Boston and Quabbin Reservoir, Ma ssachusetts). The first three sites are Speciation Trends locations, while the Reservoi r site is part of the IMPROVE protocol network. 11

11 To provide a more direct comparison of the differences between the urban and rural sites, only those days for which both monitors in a pair had data were used. Fo ur seasonal averages were computed for 2002, with seasons defined as winter (January, February, December), spring (March, April, May), Summer (June, July, August) and Fall (September, October, November). Jul y 7 was excluded from the analysis because the Quebec forest fires affecting the region on that day would h ave dominated the summertime averages. The major fine particle species categories considered included ammoni um sulfate, ammonium nitrate, organic carbon, elemental carbon, and soil mass. The traditional assump tions about these constituents were made; all sulfate was fully neutralized and a multiplier of 1.4 w as used to account for mass of organic carbon. An
“other PM 2.5 mass” category was created to delineate the difference between grav imetric mass determined
from the Teflon filter and the reconstructed mass sum of the i ndividual mass constituents. Where no “other” mass is graphed, the sum of the species either equaled or exceeded the directly measured mass. No adjustments were made to account for the different operational definitions of carbon between the IMPROVE and STN networks. Average blank corrections were ap plied to all samples. In the case of New York City, both rural and urban monitors were STN. The B oston pair reflects not only inter-site differences, but also differences in definition of organic and elemental carbon. However, the general interpretation of the data differences remains consistent. Based on current understanding, the rural
elemental carbon would be even lower than what is shown on the graph if it were made consistent with the STN definition of EC. Likewise, the organic carbon value would increase slightly for the rural value, as thePM 2.5 and Regional Haze Air Quality Problems in the MANE -VU Region: A Conceptual Description Page 2-5

EC would be allocated to OC. The urban OC levels are so mu ch greater than those in the rural area that a slight increase in rural OC makes little difference. Figure 2-3. New York nonattainment area (Elizabeth , NJ) compared

to an upwind background site (Chester, NJ)

2002 Urban-Rural PM 2.5

0 5 10 15 20 25NJBGNJBGNJBGNJBGNJBGMass (ug/m3) Other PM2.5 Soil EC_STN OCM_STN AmmNO3 AmmSO4

annual winter spring summer fall

Figure 2-4. Boston urban area (Boston, MA) compare d to an upwind background site (Quabbin Reservoir, MA )

2002 Urban-Rural PM 2.5



### 0 2 4 6 8 10 12 14 16BostonBGBostonBGBostonBGBostonBGBostonBGMass (ug/m3) 

### Other PM2.5
Soil EC_STN OCM_STN
AmmNO3
AmmSO4

annual winter spring summer fallPM 2.5 and Regional Haze Air Quality Problems in the MANE -VU Region: A Conceptual Description Page 2-6

The urban-rural differences show consistency for bo th the New York City nonattainment area and Boston. On an annual scale, the sulfate levels are comparable, with increased mass loading at these urban sites dr iven primarily by differences in
nitrates and carbon with smaller differences in “so il” levels. One interesting aspect of this comparison is the seasonal differences in the urban -rural sulfate split. On an annual basis, sulfate appears to be similar at urban and rural lo cations (based on these two pair of sites); however, during the colder months, the urba n sulfate levels are elevated relative to the rural levels. This behavior is opposite during the summer. During the wintertime, the
Northeast urban corridor itself is a substantial so urce of sulfur emissions. These local emissions can be trapped near the surface during th e winter and have a corresponding higher impact on the urban area relative to the rur al area.

For both urban and rural areas, the summertime OC le vels are significantly greater than wintertime concentrations. Although t he oxidation chemistry slows in winter, the cooler temperatures change the phase dy namics, driving more mass into the condensed over the gas phase. This along with more frequent temperature inversions (which limit atmospheric ventilation of the urban b oundary layer) can lead to the
observed increases in the relative influence of bot h organic and nitrate levels during winter months. EC, OC, and nitrate all are observed to have higher measured levels in the urban area (but still lower than the comparable sum mer values measured at the same sites), driven by local sources of these constituen ts.



### 2.3. Geographic considerations and attribution of PM 2.5 

### /haze contributors
In the East, both annual average and maximum daily fine particle concentrations are highest near heavily industrialized areas and p opulation centers. Not surprisingly, given the direct connection between fine particle p ollution and haze, the same pattern emerges when one compares measures of light extinct ion on the most and least visibility impaired days at parks and wilderness areas subject to federal haze regulations in the MANE-VU region (NESCAUM, 2001). An accumulation of particle pollution often results in hazy conditions extending over thousands of square kilometers (km 2 ) (NARSTO, 2003). Substantial visibility impairment is a frequent occurrence in even the most remote and pristine areas of the MANE-VU regio n (NESCAUM, 2001).

PM 2.5 mass declines fairly steadily along a southwest to northeast transect of the MANE-VU region. This decline is consistent with th e existence of large fine particle emissions sources (both primary and secondary) to t he south and west of MANE-VU. This trend is driven, in large part, by the marked southwest-to-northeast gradient in ambient sulfate concentrations during three seasons of the year as illustrated in Figure 2-5. Wintertime concentrations, by contrast, are fa r more uniform across the entire region. Figure 2-6 shows that on an annual basis, b oth total PM 2.5 and sulfate mass are highest in the southwestern portions of the MANE-VU region (note the different scales for each pollutant). High concentrations of nitrat e and organic particle constituents, which play a role in localized wintertime PM 2.5 episodes, tend to be clustered along the northeastern urban corridor and in other large urba n centers.PM 2.5 and Regional Haze Air Quality Problems in the MANE -VU Region: A Conceptual Description Page 2-7

Figure 2-5. 2002 Seasonal average SO 4 based on IMPROVE and STN data

Figure 2-6. 2002 Annual average PM 2.5 , sulfate, nitrate and total carbon for MANE-VU based on IMPROVE (I) and STN (S) data. PM 2.5 mass data are supplemented by measurements from the FRM netwo rk (•).PM 2.5 and Regional Haze Air Quality Problems in the MANE -VU Region: A Conceptual Description Page 2-8

While these figures provide some preliminary contex t for identifying sources contributing to the region’s particulate matter and visibility problems, they say nothing about the relative efficiency of a state’s or regio n’s emissions in contributing to the problem. It is clear that distance from the emissi ons source matters. Local, nearby sources are exceedingly important and sources withi n about 200 km are much more efficient (on a per ton emitted basis) at producing pollution impacts at eastern Class I
sites such as Shenandoah National Park than emission s sources farther away (USNPS, 2003). In general, the “reach” of sulfate air poll ution resulting from SO 2 emissions is longest (650–950 km). The reach of ammonia emission s or reduced nitrogen relative to nutrient deposition is the shortest (around 400 km) , while oxides of nitrogen and sulfur — in terms of their impacts with respect to acidic deposition — have a reach between 550–650 km and 600–700 km, respectively (USNPS, 2003).
Monitoring evidence indicates that non-urban visibi lity impairment in eastern North America is predominantly due to sulfate parti cles, with organic particles generally second in importance (NARSTO, 2003). This makes sen se, given the “long reach” of
SO 2 emissions once they are chemically transformed int o sulfate and given the ubiquitous nature of OC sources in the East. The poorest visi bility conditions occur in highly industrialized areas encompassing and adjacent to t he Ohio River and Tennessee Valleys. These areas feature large coal-burning power statio ns, steel mills, and other large emissions sources. Average fine particle concentrat ions and visibility conditions are also poor in the highly populated and industrialized mid -Atlantic seaboard but improve gradually northeast of New York City (Watson, 2002)

. A review of source apportionment and ensemble traje ctory analyses conducted by USEPA (2003) found that all back trajectory analyses for eastern sites associated sulfate with the Ohio River Valley area. These studies also are frequently able to associate other types of industrial pollutants (e.g., copper or zin c smelting, steel production, etc.) with known source areas, lending credibility to their pe rformance. Several studies in the USEPA review noted transport across the Canadian bord er, specifically sulfates from the midwestern United States into Canada, and smelter em issions from Canada into the
northeastern United States.
A recent, comprehensive analysis of air quality pro blems at Shenandoah National Park conducted by the U.S. National Park Service (USNPS, 2 003) focused on contributions to particulate pollution and visibili ty impairment south of the MANE-VU region. In descending order of importance, the Park Service analysis determined that Ohio, Virginia, West Virginia, Pennsylvania, and Ken tucky comprise the top five of 13 key states contributing to ambient sulfate concentr ations and haze impacts at the park. West Virginia, Ohio, Virginia, Pennsylvania, and Ken tucky comprise the top five contributing states with respect to sulfur depositi on impacts at the park. Finally, Virginia, West Virginia, Ohio, Pennsylvania, and North Carolin a were found to be the top five states contributing to deposition impacts from oxid ized nitrogen at the park (USNPS, 2003).

In sum, the Park Service found that emission sources located within a 200 km (125 mile) radius of Shenandoah cause greater visibi lity and acidic deposition impacts at the park, on a per ton basis, than do more distant emissions sources (USNPS, 2003). When mapping deposition and concentration patterns for all three pollutants usingPM 2.5 and Regional Haze Air Quality Problems in the MANE -VU Region: A Conceptual Description Page 2-9

contour lines, the resulting geographic pattern sho ws a definite eastward tilt in the area of highest impact. This is the result of prevailing w ind patterns, which tend to transport most airborne pollutants in an arc 12 from the north-northeast to the east. The Park Servi ce found, for example, that emissions originating in t he Ohio River Valley end up three times farther to the east than to the west (USNPS, 200 3).
The recent sulfate attribution work completed by MA NE-VU (NESCAUM, 2006) finds that a variety of different states contribute to observed sulfate in rural locations across the MANE-VU region, but that in the southwes t portions of the region, neighboring RPOs contribute to a more significant de gree relative to rural areas in the Northeast. Figure 2-7 shows relative contributions of RPOs to sulfate at three MANEVU Class I areas and one VISTAS Class I area based on a variety of analysis methods. Figure 2-8 shows the individual state contributions to sulfate at Brigantine Wilderness Area on the New Jersey coast according to tagged RE MSAD modeling.

12 The prevailing winds are eastward to northeast. This leads to greater pollution transport to the eastnortheast relative to other directions. Figure 2-7. 2002 Annual average contribution to PM 2.5 sulfate as determined by multiple analysis methods for four Class I areas sp anning MANE-VU and VirginiaPM 2.5 and Regional Haze Air Quality Problems in the MANE -VU Region: A Conceptual Description Page 2-10



### 2.4. CAIR Modeling
The CAIR modeling by the USEPA provides information o n the upwind areas (by state) contributing to downwind nonattainment for PM 2.5 in MANE-VU counties. Table 2-1 presents the upwind states significantly contri buting to PM 2.5 nonattainment in counties within MANE-VU during 2001, according to s ignificance criteria used by the USEPA (USEPA, 2005, from Table VII-3). The states lis ted in the table as significantly contributing to downwind nonattainment in MANE-VU c ounties include states outside of MANE-VU, indicating the broad regional scale of the PM 2.5 transport problem.
Table 2-2 provides the maximum contribution from ea ch state to annual average
PM 2.5 nonattainment in a downwind state (not necessarily restricted to MANE-VU nonattainment counties) based on CAIR modeling.

Figure 2-8. 2002 Annual average mass contribution to PM 2.5 at Brigantine Wilderness in New Jersey (IMPROVE) and s ulfate contributions as determined by

tagged REMSAD model simulations (NESCAUM, 2006)

0 2 4 6 8 10 12

Brigantine

Sulfate Nitrate EC OC Sea Salt Soil 

### 2000-2004 average
IMPROVE mass REMSAD 2002 average
contributions to sulfateμg/m3

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% Outside Boundary

Canada

CENRAP

DC

MS

VT

RI

ME

CT

NH

AL

WI

TN

SC

IL

KY

GA

MI

MA

IN

DE

NJ

NC

VA

WV

MD

NY

OH

PA 0 2 4 6 8 10 12

Brigantine

Sulfate Nitrate EC OC Sea Salt Soil 

### 2000-2004 average
IMPROVE mass REMSAD 2002 average
contributions to sulfateμg/m3

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% Outside Boundary

Canada

CENRAP

DC

MS

VT

RI

ME

CT

NH

AL

WI

TN

SC

IL

KY

GA

MI

MA

IN

DE

NJ

NC

VA

WV

MD

NY

OH

PAPM 2.5 and Regional Haze Air Quality Problems in the MANE -VU Region: A Conceptual Description Page 2-11

Table 2-1. Upwind states that make a significant c ontribution to PM 2.5 in each

downwind nonattainment county (2001 modeling).

Downwind State/County Upwind States

DE New Castle MD/DC MI NY OH PA VA WV

DC District of
Columbia NC OH PA VA WV

MD Anne Arundel NC OH PA VA WV

MD Baltimore City NC OH PA VA WV
NJ Union MD/DC MI NY OH PA WV
NY New York MD/DC OH PA WV PA Allegheny IL IN KY MI OH WV
PA Beaver IN MI OH WV
PA Berks MD/DC MI NY OH VA WV
PA Cambria IN MD/DC MI OH WV PA Dauphin MD/DC MI OH VA WV
PA Delaware MD/DC MI OH VA WV
PA Lancaster IN MD/DC MI NY OH VA WV PA Philadelphia MD/DC MI OH VA WV PA Washington IN KY MI OH WV
PA Westmoreland IN KY MD/DC MI OH WV
PA York MD/DC MI OH VA WV

Table 2-2. Maximum downwind PM 2.5 contribution (μg/m 3 ) for each of the 37 upwind states (2001 data).

Upwind State Maximum

Downwind Contribution Upwind State Maximum
Downwind Contribution
Alabama 0.98 Nebraska 0.07 Arkansas 0.19 New Hampshire <0.05 Connecticut <0.05 New Jersey 0.13
Delaware 0.14 New York 0.34
Florida 0.45 North Carolina 0.31 Georgia 1.27 North Dakota 0.11
Illinois 1.02 Ohio 1.67
Indiana 0.91 Oklahoma 0.12 Iowa 0.28 Pennsylvania 0.89
Kansas 0.11 Rhode Island <0.05 Kentucky 0.9 South Carolina 0.4
Louisiana 0.25 South Dakota <0.05
Maine <0.05 Tennessee 0.65 Maryland/DC 0.69 Texas 0.29
Massachusetts 0.07 Vermont <0.05 Michigan 0.62 Virginia 0.44 Minnesota 0.21 West Virginia 0.84 Mississippi 0.23 Wisconsin 0.56
Missouri 1.07PM 2.5 and Regional Haze Air Quality Problems in the MANE -VU Region: A Conceptual Description Page 2-12



### 2.5. Seasonal differences
Eastern and western coastal regions of the United St ates and Canada show marked seasonality in the concentration and composition of fine particle pollution, while central interior regions do not (NARSTO, 2003). While MANE -VU extends inland as far as the Pennsylvania and Ohio border, the majority of PM 2.5 NAAQS nonattainment areas and Class I areas affected by the Regional Haze Rule cl uster along the East Coast and thus typically show strong seasonal influences. Maximum PM 2.5 concentrations typically occur during the summer over most of the rural Nort heast, with observed summer values for rural areas in the region, on average, twice th ose of winter. In urban locations,
summertime and wintertime PM 2.5 levels are more comparable and whether one season
dominates over the other is more of a function of i nter-annual variability of meteorology and fire activity (i.e., summertime fire activity c an push average PM 2.5 values higher in some years). As described below, the reason for th e wintertime strength of PM 2.5 levels in urban areas is related to the greater concentrat ion of local pollution that accumulates when temperature inversions are present, significan tly boosting the wintertime PM 2.5 levels. Winter nitrate concentrations are generally higher than those observed in summer and, as mentioned above, urban concentrations typic ally exceed rural concentrations year-round. In addition, local mobile source carbo n grows in importance during wintertime. Hence, in some large urban areas such as Philadelphia and New York City, peak concentrations of PM 2.5 can occur in winter.
The conceptual descriptions that explain elevated r egional PM 2.5 peak concentrations in the summer differs significantly from those that explain the largely urban peaks observed during winter. On average, sum mertime concentrations of sulfate
in the northeastern United States are more than twic e that of the next most important fine particle constituent, OC, and more than four times the combined concentration of nitrate and black carbon (BC) constituents (NARSTO, 2003). Episodes of high summertime sulfate concentrations are consistent with stagnant meteorological flow conditions upwind of MANE-VU and the accumulation of airborne sulfate (via atmospheric
oxidation of SO 2 ) followed by long-range transport of sulfur emissions from industrialized areas within and outside the region.

National assessments (NARSTO, 2003) have indicated t hat in the winter, sulfate levels in urban areas are almost twice as high as b ackground sulfate levels across the eastern U.S., indicating that the local urban contri bution to wintertime sulfate levels is comparable in magnitude to the regional sulfate con tribution from long-range transport. MANE-VU’s network analysis for the winter of 2002 s uggests that the local
enhancement of sulfate in urban areas of MANE-VU is somewhat less with ranges from 25 to 40% and that the long-range transport compone nt of PM 2.5 sulfate is still the
dominant contributor in most eastern cities.

In the winter, urban OC and sulfate each account fo r about a third of the overall
PM 2.5 mass concentration observed in Philadelphia and New York City. Nitrate also makes a significant contribution to urban PM 2.5 levels observed in the northeastern United States during the winter months. Wintertime c oncentrations of OC and NO 3 in urban areas can be twice the average regional conce ntrations of these pollutants,PM 2.5 and Regional Haze Air Quality Problems in the MANE -VU Region: A Conceptual Description Page 2-13

indicating the importance of local source contribut ions (NARSTO, 2003). This is likely
because winter conditions are more conducive to the formation of local inversion layers that prevent vertical mixing. Under these conditio ns, emissions from tailpipe, industrial,
and other local sources become concentrated near th e Earth’s surface, adding to background pollution levels associated with regiona lly transported emissions.
It is worth noting that while sulfate plays a signi ficant role in episodes of elevated particle pollution during summer and winter months, the processes by which sulfate forms may vary seasonally. Nearly every source app ortionment study reviewed by USEPA (2003) identified secondary sulfate originating from coal combustion sources as the largest or one of the largest contributors to o verall fine particle mass in the region. It often accounted for more than 50 percent of PM 2.5 mass at some locations during some seasons. In a few cases, source apportionment studi es identified a known local source of sulfate, but most assessments (in conjunction with back trajectory analysis) have pointed to coal-fired power plants in the Midwest as an imp ortant source for regional sulfate. Studies with multiple years of data have also tended to identify a distinguishable chemical “signature” for winter versus summer sourc es of sulfate, with the summer version typically accounting for a greater share of overall fine particle mass. Researchers have speculated that the two profiles represent two extremes in the chemical transformation processes that occur in the atmosphe re between the source regions where emissions are released and downwind receptor sites. We note that while coal combustion
is often referred to as the “sulfate source” becaus e of the dominance of its sulfate contribution, coal combustion is often a source of significant amounts of organic carbon and is usually the single largest source of seleniu m (Se) and other heavy metal trace elements (USEPA, 2003).

Figure 2-9. Moving 60-day average of fine aerosol mass concentrations based on long-term data from two northeastern citie sPM 2.5 and Regional Haze Air Quality Problems in the MANE -VU Region: A Conceptual Description Page 2-14

In general, fine particle concentrations in MANE-VU are highest during the warmest (summer) months but also exhibit a secondar y peak during the coldest (winter) months that can dominate during some years, particu larly in urban locations. This bimodal seasonal distribution of peak values is rea dily apparent in Figure 2-9. The figure shows the smoothed 60-day running average of fine p article mass concentrations using continuous monitoring data from two northeastern ci ties over a period of several years.
Figure 2-10 also demonstrates this bimodal pattern. Though slightly more difficult to discern in just a single year’s worth of data, a “W” pattern does emerge at almost all sites across the region during 2002 with the winter peak somewhat lower than the summer peak at most sites. Urban monitors in W ilmington, Delaware and New Haven, Connecticut have wintertime peak values appr oaching those of summer.
In the summertime, MANE-VU sites repeatedly experie nce sulfate events due to transport from regions to the south and west. Duri ng such events, both rural and urban sites throughout MANE-VU record high (i.e., >15 μg/ m 3 ) daily average PM 2.5 concentrations. Meteorological conditions during t he summer frequently allow for summer “stagnation” events when very low wind speed s and warm temperatures (upwind and over MANE-VU) allow pollution levels to build i n an air mass as it slowly moves across the continent. During these events, atmosphe ric ventilation is poor and local emission sources add to the burden of transported p ollution with the result that concentrations throughout the region (both rural an d urban) are relatively uniform. Generally, there are enough of these events to driv e the difference between urban and rural sites down to less than 1 μg/m 3 during the warm or hot months of the year. As a result, concentrations of fine particles aloft will often be higher than at ground-level during the summertime, especially at rural monitori ng sites. Thus, when atmospheric “mixing” occurs during summer 13 mornings (primarily 7 to 11 a.m.), fine particle concentrations at ground-level can actually increas e (see Hartford, CT or Camden, NJ in Figure 2-11).

13 Here we define summer as May, June, July and August. Figure 2-10. The 30-day average PM 2.5 concentrations from 8 northeastern cities during 2 002PM 2.5 and Regional Haze Air Quality Problems in the MANE -VU Region: A Conceptual Description Page 2-15

Figure 2-11. Mean hourly fine aerosol concentration s during 2002 summer months

Fine Aerosol Diurnal Pattern at 18 MANE-VU Sites

0 5 10 15 20 25 30

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23ug/m3

Hartford, CT New Haven, CT Waterbury, CT Wilmington, DE Lewiston, ME Portland, ME Bangor, ME Camden, NJ Newark, NJ Trenton, NJ Elizabeth, NJ NY City, NY Buffalo, NY Rochester, NY Pittsburgh, PA Burlington, VT Rutland, VT Boston, MA

Figure 2-12. Mean hourly fine aerosol concentration s during 2002 winter months

Fine Aerosol Diurnal Pattern at 18 MANE-VU Sites

0 5 10 15 20 25

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23ug/m3

Hartford, CT New Haven, CT Waterbury, CT Wilmington, DE Lewiston, ME Portland, ME Bangor, ME Camden, NJ Newark, NJ Trenton, NJ Elizabeth, NJ NY City, NY Buffalo, NY Rochester, NY Pittsburgh, PA Burlington, VT Rutland, VT Boston, MAPM 2.5 and Regional Haze Air Quality Problems in the MANE -VU Region: A Conceptual Description Page 2-16

During the wintertime, strong inversions frequently trap local emissions overnight and during the early morning, resulting in elevated urban concentrations. These
inversions occur when the Earth’s surface loses the rmal energy by radiating it into the atmosphere (especially on clear nights). The resul t is a cold, stable layer of air near the ground. At sunrise, local emissions (both mobile a nd stationary) begin increasing in strength and build-up in the stable ground layer (w hich may extend only 100 meters or less above the ground). Increasing solar radiation during the period between 10 a.m. and noon typically breaks this cycle by warming the gro und layer so that it can rise and mix with air aloft. Because the air aloft during winte rtime is typically less polluted than the surface layer, this mixing tends to reduce ground-l evel particle concentrations (see Figure 2-12). This diurnal cycle generally drives wintert ime particle concentrations, although the occasional persistent temperature inversion can have the effect of trapping and concentrating local emissions over a period of seve ral days, thereby producing a significant wintertime pollution episode.
Rural areas experience the same temperature inversi ons but have relatively fewer
local emissions sources so that wintertime concentr ations in rural locations tend to be lower than those in nearby urban areas. Medium and long-range fine particle transport events do occur during the winter but to a far less er extent than in the summertime. In sum, it is the interplay between local and distant sources together with seasonal meteorological conditions that drives the observed 3–4 μ g/m 3 wintertime urban-rural
difference in PM 2.5 concentrations.
Visually hazy summer days in the Northeast can appe ar quite different from hazy winter days. The milky, uniform visibility impairme nt shown in Figure 2-13 is typical of summertime regional haze events in the Northeast. D uring the winter, by comparison, reduced convection and the frequent occurrence of s hallow inversion layers often creates a layered haze with a brownish tinge, as shown in Fi gure 2-14. This visual difference suggests seasonal variation in the relative contrib ution of different gaseous and particle constituents during the summer versus winter months (NESCAUM, 2001). Rural and inland areas tend not to experience these layered h aze episodes as frequently due to the
lack of local emission sources in most rural areas (valleys with high wood smoke contributions are an exception).
Overall (regional) differences in summer versus win ter particle mass concentrations and corresponding visibility impairm ent (as measured by light extinction) are largely driven by seasonal variation in sulfate mass concentrations. This is because winter meteorological conditions are less conducive to the oxidation of sulfate from SO 2 (as borne out by the previously cited source apport ionment studies). In addition, seasonal differences in long-range transport patterns from u pwind SO 2 source regions may be a
factor.
The greater presence of nitrate during the cold sea son is a consequence of the chemical properties of ammonium nitrate. Ammonia bo nds more weakly to nitrate than it does to sulfate, and ammonium nitrate tends to diss ociate at higher temperatures. Consequently, ammonium nitrate becomes more stable at lower temperatures and hence
contributes more to PM 2.5 mass and light extinction during the winter months relative to the summer (NESCAUM, 2001).PM 2.5 and Regional Haze Air Quality Problems in the MANE -VU Region: A Conceptual Description Page 2-17



### 2.6. Summary
The presence of fine particulate matter in ambient air significantly degrades public health and obscures visibility during most p arts of the year at sites across the MANE-VU region. Particle pollution generally, and i ts sulfate component specifically, constitute the principle driver for regional visibi lity impacts. While the broad region experiences visibility impairment, it is most sever e in the southern and western portions of MANE-VU that are closest to large power plant SO 2 sources in the Ohio River and Tennessee Valleys.
Summer visibility impairment is driven by the presen ce of regional sulfate, whereas winter visibility depends on a combination of regional and local influences coupled with local meteorological conditions (inver sions) that lead to the concentrated build-up of pollution.
Sulfate is the key particle constituent from the sta ndpoint of designing control strategies to improve visibility conditions in the northeastern United States. Significant
further reductions in ambient sulfate levels are ac hievable, though they will require more than proportional reductions in SO 2 emissions.
Long-range pollutant transport and local pollutant emissions are important, especially along the eastern seaboard, so one must also look beyond the achievement of further sulfate reductions. During the winter month s, in particular, consideration also needs to be given to reducing urban sources of SO 2 , NO X and OC (NARSTO, 2003) .

Figure 2-13. Summertime at Mt. Washington Clean Day Typical Haze Event

Figure 2-14. Wintertime in Boston Clean Day Typical Haze EventPM 2.5 and Regional Haze Air Quality Problems in the MANE -VU Region: A Conceptual Description Page 2-18



### References

Husar, R.B. and W.E. Wilson, “Haze and Sulfur Emissi on Trends in the Eastern United States”, Environ. Sci. Technol. 1993, 27 (1), 12-16.

Malm, W.C., B.A. Schichtel, R. B. Ames, and K. A. Ge bhart (2002), “A 10-year spatial and temporal trend of sulfate across the United Stat es,” J. Geophys. Res . 107(D22):4627, doi:10.1029/2002JD002107.

NARSTO, Particulate Matter Science for Policy Makers: A NARSTO Assessme nt , EPRI 1007735, February, 2003.

NESCAUM, Regional Haze and Visibility Impairment in the Nort heast and Mid-Atlantic
United States , Northeast States for Coordinated Air Use Managemen t, Boston, MA, January, 2001.

NESCAUM, 2002: A Year in Review , Northeast States for Coordinated Air Use Management, Boston, MA, December, 2004b.

NESCAUM, Contributions to Regional Haze and Visibility Impai rment in the Northeast and Mid-Atlantic United States, Northeast States for Coordinated Air Use Management

, Boston, MA, June, 2006.

USEPA, COMPILATION OF EXISTING STUDIES ON SOURCE APPORTION MENT
FOR PM

2.5 , Second Draft , Emissions, Monitoring, and Analysis Division, Off ice of Air Quality Planning and Standards, Research Triangle Park , NC, August, 2003.

USNPS, Assessment of Air Quality and Related Values in She nandoah National Park

, Technical Report NPS/NERCHAL/NRTR-03/090, U.S. Departm ent of the Interior, National Park Service, Northeast Region, Philadelphia, Pennsylvania, May, 2003.

Watson, J., “Visibility: Science and Regulation”, JAWMA 52:628-713, 2002.

West, J.J., Ansari, A.S., and S. N. Pandis, “Marginal PM 2.5 : Nonlinear Aerosol Mass Response to Sulfate Reductions in the Eastern United States.” JAWMA 49:1415-1424, 1999.

USEPA, “Technical Support Document for the Final Clean Air Interstate Rule, Air Quality Modeling.” U.S. Environmental Protection Ag ency Office of Air Quality Planning and Standards. March 2005

.PM 2.5 and Regional Haze Air Quality Problems in the MANE -VU Region: A Conceptual Description Page 3-1



## 3. MANE-VU EMISSION INVENTORY CHARACTERISTICS FOR FINE PARTICLES

The pollutants that affect fine particle formation and visibility are sulfur oxides (SO X ), NO X , VOCs, ammonia (NH 3 ), and particles with an aerodynamic diameter less than or equal to 10 and 2.5 μm (i.e., primary PM 10 and PM 2.5 ). The emissions dataset
illustrated in this section is the 2002 MANE-VU Ver sion 2 regional haze emissions inventory. The MANE-VU regional haze emissions inv entory version 3.0, released in April 2006, has superseded version 2 for modeling p urposes.



### 3.1. Emissions inventory characteristics

3.1.1. Sulfur dioxide (SO 2 

### )

SO 2 is the primary precursor pollutant for sulfate par ticles. Ammonium sulfate particles are the largest contributor to PM 2.5 mass on an annual average basis at MANEVU nonattainment sites. It also accounts for more than 50 percent of particle-related light extinction at northeastern Class I areas on t he clearest days and for as much as or more than 80 percent on the haziest days. Hence, SO 2 emissions are an obvious target of opportunity for both addressing PM 2.5 nonattainment and for reducing regional haze in the eastern United States. Combustion of coal and, to a substantially lesser extent, of certain petroleum products accounts for most anthro pogenic SO 2 emissions. In fact, in 1998 a single source category — coal-burning power plants — was responsible for twothirds of total SO 2 emissions nationwide (NESCAUM, 2001).
Figure 3-1 shows SO 2 emissions trends in MANE-VU states 14 extracted from the National Emissions Inventories (NEI) for the years 1996, 1999 (MARAMA, 2004), and the 2002 MANE-VU inventory. Most of the states (wi th the exception of Maryland) show declines in year 2002 annual SO 2 emissions as compared to 1996 emissions. Some of the states show an increase in 1999 followed by a decline in 2002 and others show consistent declines throughout the entire period. The upward trend in emissions after 1996 probably reflects electricity demand growth du ring the late 1990s combined with the availability of banked SO 2 emissions allowances from initial over-compliance with control requirements in Phase 1 of the USEPA Acid Rain Program. This led to relatively low market prices for allowances later in the decad e, which encouraged utilities to purchase allowances rather than implement new contr ols as electricity output expanded.
The observed decline in the 2002 SO 2 emissions inventory reflects implementation of the second phase of the USEPA Acid Rain Program, which in 2000 further reduced
allowable emissions and extended emissions limits t o more power plants.
Figure 3-2 shows the percent contribution from diffe rent source categories to
overall annual 2002 SO 2 emissions in MANE-VU states. The chart shows that point
sources dominate SO 2 emissions, which primarily consist of stationary c ombustion sources for generating electricity, industrial ener gy, and heat. Smaller stationary combustion sources called “area sources” (primarily commercial and residential heating)

14 The description of MANE-VU state inventories discussed throughout this section does not include the portion of Virginia in the Washington, DC metropolitan a rea.PM 2.5 and Regional Haze Air Quality Problems in the MANE -VU Region: A Conceptual Description Page 3-2

are another important source category in MANE-VU st ates. By contrast, on-road and non-road mobile sources make only a relatively smal l contribution to overall SO 2 emissions in the region (NESCAUM, 2001).

Figure 3-1. State level sulfur dioxide emissions

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4

Conne ct icut

D elaw a r e

D i strict of Colum

b ia Main e

M ar yl a nd

M as sachu set t s New Hampshire

New Je r sey New York Pennsylvania Rhode I s l and

V e r montmillion t/y NEI 1996

NEI 1999

MV 2002 v.2

Figure 3-2. 2002 MANE-VU state SO 2 inventories

0% 25% 50% 75% 100%

Co n ne c tic ut Delawar e

Di s trict of Columbia Maine Maryla

nd

Mas s ac h us e tts New Hamp s hi r e
Ne w J ers ey Ne w Y ork Pennsylvania

Rh ode I s l a n d

V ermont 0.0

0.2 0.4 0.6 0.8 1.0 1.2million t/y

AREA NONROAD ONROAD POINT Emission
Figure Key: Bars = Percentage fractions of four so urce categories; Circles = Annual emissions amount
in 10 6 tons per year. Note that Version 2 of the MANE-VU inventory was used and the Virginia portion of the Washington, DC metropolitan area is not show n in the figure.PM 2.5 and Regional Haze Air Quality Problems in the MANE -VU Region: A Conceptual Description Page 3-3



### 3.1.2. Volatile organic compounds (VOCs)
Existing emission inventories generally refer to VO Cs based on their historical contribution to ozone formation. From a fine partic le perspective, VOCs (also referred to as hydrocarbons) are of concern because they can re act in the atmosphere to form secondary organic aerosol (SOA) as a result of conde nsation and oxidation processes. The SOA component of fine particles also obscures vi sibility, but this component has a smaller impact on visibility (on a per unit mass ba sis) relative to sulfate or nitrate, which have an affinity for water that allows them to sign ificantly “grow” as particles under humid conditions. Nonetheless, organic carbon typi cally has the second largest visibility impact at most Class I sites next to sulfate, given its large mass contribution.
As shown in Figure 3-3, the VOC inventory is dominat ed by mobile and area sources. Most VOC emissions in MANE-VU, however, c ome from natural sources, which are not shown in the figure. Among the human -caused VOC emissions, on-road
mobile sources of VOCs include exhaust emissions fr om gasoline passenger vehicles and diesel-powered heavy-duty vehicles as well as evapo rative emissions from transportation fuels. VOC emissions may also originate from a var iety of area sources (including solvents, architectural coatings, and dry cleaners) as well as from some point sources (e.g., industrial facilities and petroleum refineri es).
Naturally occurring (biogenic) VOC emissions are ca used by the release of natural organic compounds from plants in warm weath er. Natural, or biogenic, VOCs contribute significantly to fine particle formation . Biogenic VOCs are not included in Figure 3-3, but nationally, they represent roughly t wo-thirds of all annual VOC emissions (USEPA, 2006). Biogenic emissions are extremely diff icult to estimate, as it requires modeling the behavior of many plants as well as the ir responses to the environment.
With regard to fine particle formation, understandi ng the transport dynamics and source regions for organic carbon is likely to be m ore complex than for sulfate. This is partly because of the large number and variety of V OC species, the fact that their transport characteristics vary widely, and the fact that a given species may undergo numerous complex chemical reactions in the atmosphe re. Thus, the organic carbon contribution to fine particles in the East is likel y to include manmade pollution transported from a distance, manmade pollution from nearby sources, and biogenic emissions, especially terpenes from coniferous fore sts.
For fine particles derived from organic carbon, the oxidation of hydrocarbon molecules containing seven or more carbon atoms is generally the most significant pathway for their formation (Odum et al. , 1997). Recent research, however, suggests that smaller reactive hydrocarbons like isoprene not onl y contribute significantly to groundlevel ozone, which may indirectly impact organic ae rosol formation, but also contribute directly to ambient organic aerosol through heterog eneous processes (Claeys et al., 2004; Kroll et al., 2005).PM 2.5 and Regional Haze Air Quality Problems in the MANE -VU Region: A Conceptual Description Page 3-4

Figure 3-3. 2002 MANE-VU state VOC inventories

0% 25% 50% 75% 100%

Connec t icut De la wa r e

Dis t rict o f C o lumbia Maine

Ma r yla n d

M a ss ac hu s ett s

Ne w H a mp s hir e
Ne w Je r sey

N e w Y or k

P e nn s ylvania

R h od e Isl an d Ve rm o ntmillion t/y

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6

AREA NONROAD ONROAD POINT Emission Figure key: Bars = Percentage fractions of four source categor ies; Circles = Annual
emissions amount in 10 6 tons per year. Note that Version 2 of the MANE-VU inv entory was used and the Virginia portion of the Washington, DC metropolitan area is not shown in the figure. Biogenic VOCs are not included in this fi gure.



### 3.1.3. Oxides of nitrogen (NO X 

### )

NO X emissions contribute directly to PM 2.5 nonattainment and visibility impairment in the eastern U.S. by forming nitrate pa rticles. Nitrate generally accounts for a substantially smaller fraction of fine partic le mass and related light extinction than sulfate and organic carbon regionally in MANE-VU. Notably, nitrate may play a more important role at urban sites and in the wintertime . In addition, NO X may have an indirect effect on summertime visibility by virtue of its role in the formation of ozone, which in turn promotes the formation of secondary o rganic aerosols (NESCAUM, 2001).
Figure 3-4 shows NO X emissions in MANE-VU at the state level. Since 198 0,
nationwide emissions of NO X from all sources have shown little change. In fac t, emissions increased by 2 percent between 1989 and 1 998 (USEPA, 2000a). This increase is most likely due to industrial sources a nd the transportation sector, as power plant combustion sources have implemented modest em issions reductions during the same time period. Most states in MANE-VU experience d declining NO X emissions from 1996 through 2002, except Massachusetts, Maryland, New York, and Rhode Island,
which show an increase in NO X emissions in 1999 before declining to levels below 1996
emissions in 2002.PM 2.5 and Regional Haze Air Quality Problems in the MANE -VU Region: A Conceptual Description Page 3-5

Monitored ambient NO X trends during the summer from 1997 to 2005 corrobo rate the downward trend in NO X emissions seen in the emissions inventories for MA NE-VU. As seen in Figure 3-5, the 24-hour (lower trend lin es) and 6 a.m.-8 a.m. (upper trend lines) NO X concentrations indicate decreases in NO X over this time period in MANE-VU.
The NO X reductions likely come from decreasing vehicle NO X emissions due to more stringent motor vehicle standards as well as NO X reductions from MANE-VU NO X Budget Program and the NO X SIP Call (mainly power plants).

Figure 3-4. State level nitrogen oxides emissions

0.0 0.2 0.4 0.6 0.8 1.0 1.2

Connectic u t Delaware District o f Columb i a Maine Ma r y lan d Massachusetts

Ne w Ha mp s hire New J ers e y Ne w Y o r k

P e nn s y lva n ia

Rh o de Isla n d Vermontmillion t/y NEI 1996

NEI 1999

MV 2002 v.2

Figure 3-5. Plot of monitored NO X trends in MANE-VU during 1997-2005

JUNE, JULY & AUGUST 1997-2005 OTC AVERAGE NOx CONCE NTRATIONS

10 15 20 25 30 35 40 45 50199719981999200020012002200320042005199719981999200020012002200320042005199719981999200020012002200320042005Average Concentration (ppb) .

JUN (all hrs) JUL (all hrs) AUG (all hrs) JUN (06-08 EST) JUL (06-08 EST) AUG (06-08 EST)

Note: Upper trend lines correspond to NO X measured from 0600-0800 EST in the morning. Lower trend lines correspond to NO X measured over entire day (created by Tom Downs, Ma ine Department of Environmental Protection).PM 2.5 and Regional Haze Air Quality Problems in the MANE -VU Region: A Conceptual Description Page 3-6

Power plants and mobile sources generally dominate s tate and national NO X emissions inventories. Nationally, power plants ac count for more than one-quarter of all
NO X emissions, amounting to over six million tons. Th e electric sector plays an even larger role, however, in parts of the industrial Mi dwest where high NO X emissions have a particularly significant power plant contribution. By contrast, mobile sources dominate
the NO X inventories for more urbanized mid-Atlantic and Ne w England states to a far greater extent, as shown in Figure 3-6. In these st ates, on-road mobile sources — a category that mainly includes highway vehicles — re present the most significant NO X source category. Emissions from non-road (i.e., of f-highway) mobile sources, primarily diesel-fired engines, also represent a substantial fraction of the inventory.

Figure 3-6. 2002 MANE-VU state NO X inventories

0% 25% 50% 75% 100%

C o nnec t i c ut

D elaware

Di s t ri ct of C ol umbi a Mai ne

M ar y land

M as sac hus etts New Hampshi

r e

N e w Jers ey Ne w York Pennsylvania

R hode I s land Vermontmillion t/y

0.0 0.3 0.6 0.9

AREA NONROAD ONROAD POINT Emission

Figure key: Bars = Percentage fractions of four source categor ies; Circles = Annual
emissions amount in 10 6 tons per year. Note that Version 2 of the MANE-VU inv entory was used and the Virginia portion of the Washington, DC metropolitan area is not shown in the figure.



### 3.1.4. Primary particulate matter (PM 10 

### and PM 2.5 

### )
Directly-emitted or “primary” particles (as distinc t from secondary particles that form in the atmosphere through chemical reactions i nvolving precursor pollutants like
SO 2 and NO X ) also contribute to fine particle levels in the at mosphere. For regulatory purposes, we make a distinction between particles w ith an aerodynamic diameter less than or equal to 10 micrometers and smaller particl es with an aerodynamic diameter less than or equal to 2.5 micrometers (i.e., primary PM 10 and PM 2.5 , respectively).PM 2.5 and Regional Haze Air Quality Problems in the MANE -VU Region: A Conceptual Description Page 3-7

Figure 3-7 and Figure 3-8 show PM 10 and PM 2.5 emissions for MANE-VU states for the years 1996, 1999, and 2002. Note that, as opposed to the other constituents of PM, the 2002 inventory values for PM 10 are drawn from the 2002 NEI. Most states show a steady decline in annual PM 10 emissions over this time period. By contrast, emi ssion trends for primary PM 2.5 are more variable.
Crustal sources are significant contributors of pri mary PM emissions. This category includes fugitive dust emissions from cons truction activities, paved and unpaved roads, and agricultural tilling. Typically, monito rs estimate PM 10 emissions from these types of sources by measuring the horizontal flux o f particulate mass at a fixed downwind sampling location within perhaps 10 meters of a roa d or field. Comparisons between estimated emission rates for fine particles using t hese types of measurement techniques
and observed concentrations of crustal matter in th e ambient air at downwind receptor sites suggest that physical or chemical processes r emove a significant fraction of crustal material relatively quickly. As a result, it rarely entrains into layers of the atmosphere where it can transport to downwind receptor locatio ns. Because of this discrepancy
between estimated emissions and observed ambient co ncentrations, modelers typically
reduce estimates of total PM 2.5 emissions from all crustal sources by applying a fa ctor of 0.15 to 0.25 before including in modeling analyses.
From a regional haze perspective, crustal material g enerally does not play a major role. On the 20 percent best-visibility days durin g the baseline period (2000-2004), it accounted for 6 to 11 percent of particle-related l ight extinction at MANE-VU Class 1 sites. On the 20 percent worst-visibility days, how ever, crustal material generally plays a much smaller role relative to other haze-forming po llutants, ranging from 2 to 3 percent. Moreover, the crustal fraction includes material of natural origin (such as soil or sea salt) that is not targeted under USEPA’s Regional Haze Rule . Of course, the crustal fraction can be influenced by certain human activities, such as construction, agricultural practices, and road maintenance (including wintertime salting) — thus, to the extent that these types of activities are found to affect visibility at nor theastern Class I sites, control measures targeted at crustal material may prove beneficial.
Experience from the western United States, where the crustal component has generally played a more significant role in driving overall particulate levels, may be helpful where it is relevant in the eastern context . In addition, a few areas in the Northeast, such as New Haven, Connecticut and Presqu e Isle, Maine, have some experience with the control of dust and road-salt a s a result of regulatory obligations stemming from their past nonattainment status with respect to the NAAQS for PM 10

. Current emissions inventories for the entire MANE-V U area indicate residential wood combustion represents 25 percent of primary fi ne particulate emissions in the region. This implies that rural sources can play a n important role in addition to the contribution from the region’s many highly populate d urban areas. An important consideration in this regard is that residential wo od combustion occurs primarily in the winter months, while managed or prescribed burning activities occur largely in other seasons. The latter category includes agricultural field-burning activities, prescribed burning of forested areas, and other burning activi ties such as construction waste burning. Limiting burning to times when favorable meteorolog ical conditions can efficiently disperse resulting emissions can manage many of the se types of sources.PM 2.5 and Regional Haze Air Quality Problems in the MANE -VU Region: A Conceptual Description Page 3-8

Figure 3-7. State level primary PM 10 emissions

0.0 0.2 0.4 0.6 0.8

Connecticut

Delaware

D i st r i ct of Col u mbi a M ai ne Mar yl and Massachusetts

New H am pshi r e

N ew Je rsey

N ew Y or k Pennsy l vania Rhode Island

V

ermontmillion t/y NEI 1996

NEI 1999

NEI 2002

Figure 3-8. State level primary PM 2.5 emissions

0.0 0.1 0.2 0.3

C onn ect i cut

D e law a re

Di st rict of Columbia M

ai ne

M arylan d

Mas s ach use tts

N ew H am pshi r e

N ew Jer sey

N ew York

P ennsyl vani a Rhode Is l and

V e rmontmillion t/y NEI 1996

NEI 1999

MV 2002 v.2

Figure 3-9 and Figure 3-10 show that area and mobile sources dominate primary
PM emissions. (The NEI inventory categorizes resident ial wood combustion and some other combustion sources as area sources.) The rel ative contribution of point sources is larger in the primary PM 2.5 inventory than in the primary PM 10 inventory since the crustalPM 2.5 and Regional Haze Air Quality Problems in the MANE -VU Region: A Conceptual Description Page 3-9

component (which consists mainly of larger or “coar se-mode” particles) contributes mostly to overall PM 10 levels. At the same time, pollution control equipm ent commonly installed at large point sources is usually more ef ficient at capturing coarse-mode particles.

Figure 3-9. 2002 MANE-VU state primary PM 10 inventories

0% 20% 40% 60% 80% 100%

C o n n ec t i cut Delawa r e

Di s tr i ct o f Co l umbia Ma

i ne Ma ryl a nd

Ma s sac h u se t t s

N e w H a mp sh i re

N e w Je rse y New York Pennsyl v ania Rhode Isla n d

V e r mo n tmillion t/y

0.0 0.1 0.2 0.3 0.4 0.5

AREA NONROAD ONROAD POINT Emission

Figure 3-10. 2002 MANE-VU state primary PM 2.5 inventories

0% 25% 50% 75% 100%

Connecticu t

D ela w a re

Di s tr i ct o f Co l u m bia Ma i n e

M a ry l a n d Massachu se tts New H a mpshire New Je rse y New Y o r k

P e nnsylvania Rhode Isl and Ver m ontmillion t/y

0.00 0.05 0.10 0.15 0.20

AREA NONROAD ONROAD POINT Emission Figure key: Bars = Percentage fractions of four so urce categories; Circles = Annual emissions amount in 10 6 tons per year. Note that Version 2 of the MANE-VU inven tory was used and the Virginia portion of the Washi ngton, DC metropolitan area is not shown in the figure.PM 2.5 and Regional Haze Air Quality Problems in the MANE -VU Region: A Conceptual Description Page 3-10



### 3.1.5. Ammonia emissions (NH 3 

### )
Knowledge of ammonia emission sources will be neces sary in developing effective regional haze reduction strategies becaus e of the importance of ammonium sulfate and ammonium nitrate in determining overall fine particle mass and light scattering. According to 1998 estimates, livestock and agriculture fertilizer use accounted for approximately 85 percent of all ammon ia emissions to the atmosphere (USEPA, 2000b). We need, however, better ammonia inv entory data for the photochemical models used to simulate fine particle formation and transport in the eastern United States. Because the USEPA does not reg ulate ammonia as a criteria pollutant or as a criteria pollutant precursor, the se data do not presently exist at the same level of detail or certainty as for NO X and SO 2

. Ammonium ion (formed from ammonia emissions to the atmosphere) is an important constituent of airborne particulate matte r, typically accounting for 10–20 percent of total fine particle mass. Reductions in ammoniu m ion concentrations can be extremely beneficial because a more-than-proportion al reduction in fine particle mass can result. Ansari and Pandis (1998) showed that a one μ g/m 3 reduction in ammonium ion could result in up to a four μ g/m 3 reduction in fine particulate matter. Decision mak ers, however, must weigh the benefits of ammonia reducti on against the significant role it plays in neutralizing acidic aerosol. SO 2 reacts in the atmosphere to form sulfuric acid (H 2 SO 4 ). Ammonia can partially or fully neutralize this strong acid to form ammonium bisulfate or ammonium sulfate. If planners focus f uture control strategies on ammonia and do not achieve corresponding SO 2 reductions, fine particles formed in the atmospher e will be substantially more acidic than those presen tly observed.
To address the need for improved ammonia inventorie s, MARAMA, NESCAUM and USEPA funded researchers at Carnegie Mellon Unive rsity (CMU) in Pittsburgh to develop a regional ammonia inventory system (Davids on et al., 1999). This study focused on three issues with respect to current emi ssions estimates: (1) a wide range of ammonia emission factor values, (2) inadequate temp oral and spatial resolution of ammonia emissions estimates, and (3) a lack of stan dardized ammonia source categories.
Figure 3-11 shows that estimated ammonia emissions w ere fairly stable in the 1996, 1999, and 2002 NEI for MANE-VU states, with s ome increases observed for Massachusetts, New Jersey and New York. Area and o n-road mobile sources dominate the ammonia inventory, according to Figure 3-12. Spec ifically, emissions from agricultural sources and livestock production accou nt for the largest share of estimated ammonia emissions in MANE-VU, except in the Distric t of Columbia. The two remaining sources with a significant emissions cont ribution are wastewater treatment systems and gasoline exhaust from highway vehicles.PM 2.5 and Regional Haze Air Quality Problems in the MANE -VU Region: A Conceptual Description Page 3-11

Figure 3-11. State level ammonia emissions

0.000 0.025 0.050 0.075 0.100

Connecticut Delaware

District of Colu

m bia M ai ne

M aryland

M assa chusetts

N ew H am pshire New Jersey

N ew Y or k Pennsyl van i a

R h ode I s l and Verm o n tmillion t/y NEI 1996

NEI 1999

MV 2002 v.2

Figure 3-12. 2002 MANE-VU state NH 3 inventories

0% 25% 50% 75% 100%

Co nnec t icut De l aware

Di str i c t o f Col u mbia Mai ne Mar y land

M as s achu set t s New Hampshire

Ne w J e rs ey New Y o r k Pennsylvania

Rh o de Is l an d Vermontmillion t/y

0.00 0.06 0.12

AREA NONROAD ONROAD POINT Emission

Figure key: Bars = Percentage fractions of four source categor ies; Circles = Annual
emissions amount in 10 6 tons per year. Note that Version 2 of the MANE-VU inv entory was used and the Virginia portion of the Washington, DC metropolitan area is not shown in the figure.PM 2.5 and Regional Haze Air Quality Problems in the MANE -VU Region: A Conceptual Description Page 3-12



### 3.2. Emissions inventory characteristics outside MANE-VU

SO 2 , NO X and VOC emissions from within MANE-VU are only one component of the emissions contributing to fine particles aff ecting the MANE-VU region. As regional modeling for the CAIR has shown, emission sources, primarily of SO 2 and NO X , located outside MANE-VU can significantly contribut e to particle sulfate and nitrate transported into the MANE-VU region. Here we prese nt regional emissions information grouped by the three eastern RPOs – MANE-VU, VISTAS (V isibility Improvement State and Tribal Association of the Southeast), and the MW RPO (Midwest RPO). Table 3-1
lists the states in each RPO.
The inventory information is extracted from the USEPA final 2002 National Emissions Inventory (NEI). For consistency, the MAN E-VU information here also
comes from the 2002 NEI rather than from the MANE-V U Version 2 regional haze emissions inventory described in Section 3.1. The d ifferences between the inventories are not great, as the NEI and the MANE-VU Version 2 inventory are both based on the same inventory information provided by the states.

Table 3-1. Eastern U.S. RPOs and their state membe rs

RPO State

MWRPO Illinois
MWRPO Indiana MWRPO Michigan
MWRPO Ohio
MWRPO Wisconsin
MANE-VU Connecticut
MANE-VU Delaware
MANE-VU District of Columbia
MANE-VU Maine MANE-VU Maryland
MANE-VU Massachusetts MANE-VU New Hampshire MANE-VU New Jersey
MANE-VU New York MANE-VU Pennsylvania
MANE-VU Rhode Island
MANE-VU Vermont
VISTAS Alabama
VISTAS Florida VISTAS Georgia VISTAS Kentucky VISTAS Mississippi
VISTAS North Carolina
VISTAS South Carolina
VISTAS Tennessee VISTAS Virginia VISTAS West VirginiaPM 2.5 and Regional Haze Air Quality Problems in the MANE -VU Region: A Conceptual Description Page 3-13

Table 3-2 presents SO 2 emissions by source sector and RPO for the eastern
United States. The NO X emissions by source sector and RPO are presented in Table 3-3 and VOC emissions in Table 3-4. Regionally, SO 2 emissions are more important with respect to regional particle formation and transpor t. NO X emissions play an important role in determining the equilibrium between ammoniu m sulfate and ammonium nitrate formation, especially during winter. VOC emissions contribute to secondary organic
aerosol formation.

Table 3-2. SO 2 emissions in eastern RPOs (tons/yr)

RPO Point Area On-road Non-road Total MWRPO 3,336,967 133,415 49,191 82,307 3,601,880 MANE-VU 1,924,573 353,176 39,368 74,566 2,391,683 VISTAS 4,349,437 448,023 83,001 91,307 4,971,769

Table 3-3. NO X emissions in eastern RPOs (tons/yr)

RPO Point Area On-road Non-road Total MWRPO 1,437,284 184,790 1,290,178 723,844 3,636,096 MANE-VU 680,975 268,997 1,297,357 534,454 2,781,783 VISTAS 2,094,228 266,848 2,160,601 812,615 5,334,293

Table 3-4. VOC emissions in eastern RPOs (tons/yr)

RPO Point Area On-road Non-road Total MWRPO 234,938 1,182,186 660,010 492,027 2,569,160 MANE-VU 93,691 1,798,158 793,541 494,115 3,179,504 VISTAS 458,740 2,047,359 1,314,979 609,539 4,430,617PM 2.5 and Regional Haze Air Quality Problems in the MANE -VU Region: A Conceptual Description Page 3-14



### References

Ansari, A.S., and S.N. Pandis. “Response of inorgani c PM to precursor concentrations.”
Environ. Sci. Technol

. 32, 2706-2714, 1998.

Claeys, M., W. Wang, A.C. Ion, I. Kourtchev, A. Gel encser, and W. Maenhaut, “Formation of secondary organic aerosols from isopre ne and gas-phase oxidation products through reaction with hydrogen peroxide.” Atmos. Environ. , 38, 4093-4098,
2004.

Davidson, C., R. Strader, S. Pandis, and A. Robinson. Preliminary Proposal to MARAMA and NESCAUM: Development of an Ammonia Emis sions Inventory for the Mid-Atlantic States and New England . Carnegie Mellon University, Pittsburgh, PA, January 7, 1999.

Kroll, J.H., N.L. Ng, S.M. Murphy, R.C. Flagan, and J .H. Seinfeld. “Secondary Organic Aerosol Formation from Isoprene Photooxidation.” Environ. Sci. Technol. 40 , 1869- 1877, 2006.

MARAMA 2004, http://www.marama.org/visibility/2002%20NEI/index.h tml

MARAMA. “A Guide to Mid-Atlantic Regional Air Qual ity,” October 2005.

NESCAUM. Regional Haze and Visibility in the Northeast and M id-Atlantic States. NESCAUM, Boston, MA, January 2001.

Odum, J.R., T.P.W. Jungkamp, R.J. Griffin, R.C. Flaga n, and J.J. Seinfeld. “The atmospheric aerosol-forming potential of whole gaso line vapor.” Science 276 , 96-99,
1997.

USEPA. National Air Quality and Emission Trends Report, 19 98 , EPA 454/R-00-003,
available online: http://www.epa.gov/oar/aqtrnd98/ , 2000a.

USEPA. National Air Pollutant Trends, 1900 – 1998 , EPA 454/R-00-002, available
online: http://www.epa.gov/ttn/chief/trends/trends98/trends 98.pdf , 2000b.

USEPA. 2002 Final National Emissions Inventory (NEI) , available online: ftp://ftp.epa.gov/EmisInventory/2002finalnei/ , 2006 (accessed October 10, 2006) [The 2002 NEI reports national annual emissions for tota l anthropogenic VOC emissions as 16.8 million tons, and total biogenic VOC emissions as 41.8 million tons].PM 2.5 and Regional Haze Air Quality Problems in the MANE -VU Region: A Conceptual Description Page 4-2



## 4. WHAT WILL IT TAKE TO CLEAN THE AIR?

In this chapter we build on the conceptual descript ion of fine particle formation and impacts in the MANE-VU region by looking at a t ypical fine particle pollution event and the meteorological and chemical conditions whic h contributed to its formation. As an illustration of how the conceptual elements laid out in Chapter 2 and 3 contribute to a pollution event under real-world circumstances, we examine a pollution event from 2002. We examine this event from two perspectives: (1) th e broad spatial patterns of the formation and transport of particle air pollution a nd (2) the chronological sequence of events at a few discrete points where high temporal resolution monitoring was in place. We then proceed to examine likely emission reductio n strategies that should be considered in light of the conceptual understanding of fine particle formation and transport developed in this report.



### 4.1. Meteorological and Pollution Overview of August 8-1 6, 2002

Annual and seasonal statistics are useful for under standing the general patterns of air pollution in our region, but it is also instruc tive to review specific high PM 2.5 episodes in order to shed more light on the meteorological c ircumstances under which high
ambient concentrations of PM 2.5 are able to form from emitted precursor pollutants . Here we present an analysis of the high PM 2.5 and regional haze episode of August 2002 by reviewing surface maps from the period to provide a synoptic overview of major weather systems that were influencing air quality across th e Northeast U.S. during that time.
Figure 4-1 through Figure 4-3, respectively, show eig ht-panel displays of afternoon fine particle concentrations as well as s urface weather maps and back trajectories from 12Z (8 a.m. EDT) each day. The f ollowing chronology of events combines the meteorological insights with PM 2.5 concentration information to provide a basic storyline for analysis.
A slow-moving high pressure system centered over th e Great Lakes set up northerly flow over MANE-VU on August 8. The high drifted southeast-ward and became extended over several days bringing high tem peratures to the region. Calm
conditions west of MANE-VU on August 10 were pivotal in the formati on of fine aerosol concentrations, which began building in the Ohio Ri ver Valley. Over the next four days, concentrations in MANE-VU climbed into the 60-90 μg /m 3 range over a wide area before being swept out to sea by a series of frontal passa ges beginning on August 15.

8/8 – A high pressure system over the Great Lakes produ ces NW-N prevailing surface winds (~4-8 mph) throughout the region. Max imum daily temperatures approach
or exceed 80o F.

8/9 – Wind speeds fall off but direction remains NW-N as the high moves into the central portion of MANE-VU. Temperatures rise as c loud cover declines.

8/10 – The high reaches the East Coast and stalls. Tem peratures (except in northern-most areas) reach 90o F while surface-level winds turn to more southerly directions. Calm conditions through the morning ho urs in the lower Ohio River Valley promote creation of haze noted in surface observati ons.PM 2.5 and Regional Haze Air Quality Problems in the MANE -VU Region: A Conceptual Description Page 4-3

8/11 – Circulation around the high (now near Cape Hatte ras) becomes well established. Peak temperatures are in the low to mi d-90’s. Morning winds are light-tocalm in the area east of the Mississippi – the area of haze now reaches from Michigan to northern Texas and eastward to West Virginia and ea stern Tennessee. A surface-level trough descends from north of the Great Lakes durin g the day, passes eastward through the Ohio River Valley and stalls over the Allegheny Mountains and southward.

8/12 – Temperatures exceed 90o F throughout MANE-VU excep t in coastal ME. The area of concentrated haze has pushed eastward a nd now extends from central ME to central PA. Haze builds throughout the day as circu lation forces it to channel NE between the stalled trough and a cold front approac hing from the Midwest.

8/13 – Calm conditions prevail as the trough reaches co astal NJ by 8 a.m. Generally clear skies allow temperatures to reach t he mid-90’s everywhere except in coastal ME. Dew points, which had been rising sinc e 8/8, reach the upper 60’s. Peak hourly fine aerosol concentrations are greater than 40 μg/m 3 everywhere in MANE-VU and exceed 90 μg/m 3 in some locations. By 8 p.m., showers associated with the approaching cold front have reached into Ohio.

8/14 – By 8 a.m. the trough has dissipated and the high is moving offshore. Dew points remain in the upper 60’s and peak temperatur es reach into the 90’s everywhere and top 100 in several locations. Increased ventilatio n causes aerosol concentrations to drop throughout the day everywhere except ME where some locations peak above 60 μg/m 3 after midnight.

8/15 – The approaching cold front and associated shower s fall apart during the morning hours. By 8 p.m., a new batch of moderate r ain has intruded deeply into the region from the SW and has virtually pushed the haze out of the MANE-VU region.

8/16 – A new high building in over the upper Midwest push es the remains of the
showers out of the Northeast.PM 2.5 and Regional Haze Air Quality Problems in the MANE -VU Region: A Conceptual Description Page 4-4

Figure 4-1. Spatially interpolated maps of fine par ticle concentrations August 9 – 16, 2002PM 2.5 and Regional Haze Air Quality Problems in the MANE -VU Region: A Conceptual Description Page 4-5

Figure 4-2. Surface weather maps for August 9-16, 2 002

August 9, 8:00AM EDT August 10, 8:00 AM EDT

August 11, 8:00 AM EDT August 12, 8:00 AM EDT

August 13, 8:00 AM EDT August 14, 8:00 AM EDT

August 15, 8:00 AM EDT August 16, 8:00 AM EDTPM 2.5 and Regional Haze Air Quality Problems in the MANE -VU Region: A Conceptual Description Page 4-6

Figure 4-3. HYSPLIT 72-hour back trajectories for A ugust 9-16, 2002 

### Aug 9, 2002 8 am EDT 

### Aug 10, 2002 8 am EDT

Aug 11, 2002 8 am EDT Aug 12, 2002 8 am EDT

Aug 13, 2002 8 am EDT Aug 14, 2002 8 am EDT

Aug 15, 2002 8 am EDT Aug 16, 2002 8 am EDTPM 2.5 and Regional Haze Air Quality Problems in the MANE -VU Region: A Conceptual Description Page 4-7



### 4.2. Temporally and spatially resolved PM 2.5 

### measurements
Higher temporal resolution data provide insight int o how the events played out in much more detail than can be captured by eight fram es on a page; however the most complete picture is obtained when these high temporal resolution data can be presented in the context of the relatively greater spatial detail provided by maps such as we have seen in Figure 4-1 through Figure 4-3. In Figure 4-4 and Figure 4-5, we present
continuous PM 2.5 data (hourly average and 24-hour rolling average f iltered, respectively) for the August 8-16, 2002 time period.

Looking at Figure 4-4 in the context of the maps pre sented in the earlier figures, it is interesting to note the rapid increase, first, i n Arendtsville, PA at noon on the 11th, followed by a rise in concentrations along the East Coast around noon on the 12th. This is consistent with Figure 4-1, which shows high PM 2.5 levels covering western Pennsylvania by 3 p.m. on the 11th and that high PM 2.5 area has moved over to cover the East Coast by 3 p.m. the next day. This also makes sense with respect to Figure 4-2 and Figure 4-3, which show the high pressure system esta blished on the East Coast by the 11th with surface level back trajectories having sh ifted from northerly flow to slow southwesterly flow in the western portion of the do main by the morning of the 11th and the coastal sites having switched by the morning of the 12th. Figure 4-4. Hourly average fine aerosol at 8 sites during the August 2002 episode

-10 0 10 20 30 40 50 60 70 80 90 100

7-Aug 8-Aug 9 -Aug 10

-Au g 11

- A u g 12

- Aug 1

3 -Aug 14

- A u g 15

- Augug/m3 Arendtsville, PA Wilmington, DE
Camden, NJ
New Brunswick, NJ NYC (Bronx), NY
Hartford, CT
Boston, MA
Portland, MEPM 2.5 and Regional Haze Air Quality Problems in the MANE -VU Region: A Conceptual Description Page 4-8

Also note the very high levels observed close to mi d-day on the 13 th at sites between New York City and Portland, Maine. This is consistent with the strong gradients shown for 3 p.m. on the 13 th in Figure 4-1. These rapid increases in concentrat ion are easily explained by the back trajectories of Figure 4-3 that show the advancing front (at this point over Lake Michigan) beginning to push, a t upper levels of the atmosphere, an air mass from the upper Midwest due east across the northern half of MANE-VU. At lower levels (see 200 meter trajectories), it can b e seen that closer to the surface, this air mass had spent the previous three to four days wind ing around the Tennessee and Ohio River Valleys before it was driven into the norther n reaches of MANE-VU at the peak of the pollution event.
The following figures bring much of this informatio n together in a single image. Figure 4-6 contains satellite photos from MODIS, a mo saic of two consecutive satellite passages on August 13, 2002 from NASA’s TERRA satel lite. Figure 4-7 shows the same image with geo-referenced activity data and invento ry information layered on top to allow for simultaneous depiction of cities, roads, point source emissions, and back trajectories that play a role in the air pollution/ haze that affected a large part of the Northeast during this episode.

Figure 4-5. 24-hour rolling average fine aerosol a t 8 MANE-VU sites during the August 2002 episode

-10 0 10 20 30 40 50 60 70 80 90 100

6-Aug 7-Aug 8-Aug 9-Aug 1 0- A u g 11-Aug 1

2-Aug 1

3-Aug 1

4-Aug 1

5- A u g 16-Augug/m3 Arendtsville, PA
Wilmington, DE

Camden, NJ

New Brunswick, NJ
NYC (Bronx), NY

Hartford, CT

Boston, MA

Portland, MEPM 2.5 and Regional Haze Air Quality Problems in the MANE -VU Region: A Conceptual Description Page 4-9

Figure 4-6. Composite images from NASA’s TERRA Sat ellite on August 13, 2002 showing fine particle pollution/haz e.

Note the milky/gray haze due to particle pollution as distin ct from the puffy white clouds over broad regions of southern New England and the eastern Mid-Atlantic region.

Figure 4-7. NASA MODIS Terra Satellite Image, Back Trajectories and NO X Inventory

Geo-referenced activity and inventory data (on top of the sat ellite images presented above) demonstrating the relationship between observed pollution and upper leve l winds (driving weather patterns from West to East), mid-level winds (tracking back to major point sou rces), and lower level winds (tracking back to major population centers along the East Coast).PM 2.5 and Regional Haze Air Quality Problems in the MANE -VU Region: A Conceptual Description Page 4-10



### 4.3. Implications for control strategies
A 2003 assessment of fine particulate matter by NAR STO 15 states, “[c]urrent airquality management approaches focusing on reduction s of emissions of SO 2 , NO X, and VOCs are anticipated to be effective first steps to wards reducing PM 2.5 across North America, noting that in parts of California and som e eastern urban areas VOC (volatile organic compounds) emissions could be important to nitrate formation.”
This conclusion seems to be well supported by the h istorical record which documents a pronounced decline in particulate sulfa te concentrations across the eastern United States during the 1990s. The timing of this observed decline suggests that this is
linked to reductions in SO 2 emissions resulting from controls implemented unde r the federal Acid Rain program beginning in the early to mid-1990s. From 1989 to 1998, SO 2 emissions in the eastern half of the country — that is, including all states within a region defined by the western borders of Minnesota and Lou isiana — declined by about 25 percent. This decline in SO 2 emissions correlated with a decline of about 40 pe rcent in average SO 2 and sulfate concentrations, as measured at Clean A ir States and Trend Networks (CASTNet) monitoring sites in the same regi on over the same time period. In fact, at prevailing levels of atmospheric SO 2 loading, the magnitudes of the emissions and concentration changes were not statistically differ ent. This finding suggests that regional
reductions in SO 2 emissions have produced near-proportional reductio ns of particulate sulfate in the eastern United States (NARSTO, 2003). Reductions since 1990 in precursor SO 2 emissions are likely also responsible for a contin ued decline in median
sulfate concentrations in the northeastern United St ates. Nevertheless, episodes of high ambient sulfate concentrations (with peak levels we ll above the regional median or average) continue to occur, especially during the s ummertime when regional transport from the Ohio River Valley is also at its peak. Thi s suggests that further reductions in regional and local SO 2 emissions would provide significant further air qua lity and visibility benefits (NARSTO, 2003).

For urban areas of the eastern United States, an effe ctive emissions management approach may be to combine regional SO 2 control efforts aimed at reducing summertime
PM 2.5 concentrations with local SO 2 and OC control efforts. Local SO 2 reductions would help reduce wintertime PM 2.5 concentrations, while OC reductions can help reduc e overall PM 2.5 concentrations year-round. For areas with high wint ertime PM 2.5 levels, strategies that involve NO X reductions may also be effective (NARSTO, 2003).
Further support for this general approach may be fou nd in a review of several studies by Watson (2002) which concluded that SO 2 emission reductions have in most cases been accompanied by statistically significant reductions in ambient sulfate concentrations. One study (Husar and Wilson, 1993) shows that regionally averaged light extinction closely tracks regionally averaged SO 2 emissions for the eastern United States from 1940 through the mid-1980s. Another study by M alm et al. (2002) shows that

15 NARSTO was formerly an acronym for the "North American Resear ch Strategy for Tropospheric Ozone." More recently, the term NARSTO became simply a wordmarksignifying a tri-national, publicprivate partnership for dealing with multiple features of t ropospheric pollution, including ozone and suspended particulate matter. For more information on NARST O see http://www.cgenv.com/Narsto/

.PM 2.5 and Regional Haze Air Quality Problems in the MANE -VU Region: A Conceptual Description Page 4-11

regionally averaged emissions and ambient concentra tions decreased together from 1988 through 1999 over a broad region encompassing the s tates of Connecticut, Delaware, Illinois, Indiana, Kentucky, Maine, Massachusetts, Maryland, Michigan, New Hampshire, New Jersey, New York, Ohio, Pennsylvania, Rhode Island, Vermont, Virginia, Wisconsin, and West Virginia (Watson, 200 2).

These studies and available data from the IMPROVE (I nteragency Monitoring of Protected Visual Environment) monitoring network pro vide strong evidence that regional
SO 2 reductions have yielded, and will continue to yiel d, reductions in ambient secondary sulfate levels with subsequent reductions in region al haze and associated light extinction. They indicate that reductions in anthropogenic prim ary particle emissions will also result in visibility improvements, but that these will not have a zone of influence as large as those of the secondary aerosols (Watson, 2002).
Watson (2002) notes that during the 65 years in whi ch the regional haze program aims to reach its final visibility goals, several o pportunities to revise this basic control approach will arise through the decadal SIP cycle. T his enables new scientific results to continue to exert a positive influence as states im plement new regulatory control programs for SO 2 , NO X and VOCs, and as ambient concentrations of these p ollutants change relative to each other and relative to ambie nt ammonia levels. As these relationships between species change, atmospheric c hemistry may dictate a revised control approach to those previously described. Fur ther research on these issues should be a priority for supporting 2018 SIP submissions. T hey include the possibility that:

• Reduction of sulfate in a fully neutralized atmosph ere (excess ammonia) could encourage ammonium nitrate formation.

• Ever-greater emissions reductions could be required to produce a given level of improvement in ambient pollutant concentra tions because of nonlinearities in the atmospheric formation of sulfate

.

• Changes in ambient conditions favoring the aqueous oxidation of sulfate (this pathway largely accounts for the non-linearit y noted above) may have implications for future emissions control prog rams. Causes of changing ambient conditions could include, for exam ple, climate change.

West et al. (1999) examine a scenario for the eastern United St ates where PM 2.5 mass decreases linearly with ammonium sulfate until the latter is fully neutralized by
ammonia. Further reductions would free ammonia for c ombination with gaseous nitric acid that, in turn, would slightly increase PM 2.5 until all of the nitric acid is neutralized
and further sulfate reductions are reflected in low er PM 2.5 mass. This is an extreme case that is more relevant to source areas (e.g., Ohio) where nitric acid (HNO 3 ) is more abundant than in areas with lower emissions (e.g., Vermont) (Watson, 2002).
In most situations with non-neutralized sulfate (ty pical of the eastern United States), ammonia is a limiting agent for the formati on of nitrate but will not make any difference until sulfate is reduced to the point wh ere it is completely neutralized. At that point, identifying large sources of ammonia emissio ns will be important. This point is likely to be many years in the future, however (Wat son, 2002).PM 2.5 and Regional Haze Air Quality Problems in the MANE -VU Region: A Conceptual Description Page 4-12

Based on analyses using the Community Multi-Scale A ir Quality (CMAQ) model, the aqueous phase production of sulfate in the Nort heast appears to be very oxidant limited and hence non-linear. Thus, conditions that are conducive to a dominance of the gas-phase production pathway drive the summer peaks in ambient sulfate levels. Nonetheless, the expected reduction in ambient sulf ate levels resulting from a given
reduction in SO 2 emissions is less than proportional overall due to the non-linearity introduced by the aqueous pathway for sulfate forma tion (NARSTO, 2003). These nonlinearity effects are more pronounced for haze than for sulfate deposition, especially at higher sulfate air concentrations (USNPS, 2003).
Finally, we note that because visibility in the clea rest areas is sensitive to even minute increases in particle concentrations, strate gies to preserve visibility on the clearest days may require stringent limits on emissions grow th. In this context, even the dilute emissions from distant sources can be important (NA RSTO, 2003)



### 4.4. Conclusion: Simplifying a complex problem
A conceptual understanding of fine particles from a regional perspective across MANE-VU and throughout the eastern U.S. is well unde rstood, yet remains complex due to the multiplicity of source regions (both regiona l and local), pollutants (SO 2 , NO X , organic carbon, and primary PM 2.5 ), and seasons (summer and winter) that are involve d in fine particle formation.
Regional approaches to the control of precursor SO 2 and NO X emissions have been started through Title IV of the Clean Air Act, the NO X SIP Call, the CAIR, and the establishment and support of Regional Planning Organ izations to assist with Regional Haze Rule compliance. With the modeling foundation developed for the CAIR program, the USEPA has presented a compelling technical case o n the need for additional regional
SO 2 and NO X reductions in the eastern U.S. to reduce particulat e levels and protect public health. While states in the Northeast disagree wit h the extent of SO 2 and NO X reductions and the timeline for those reductions to occur, the program is an excellent next step toward reducing fine particles in MANE-VU. It is t empting to suggest that the regional
control of SO 2 and NO X are the extent of the problem facing MANE-VU, but as the conceptual description contained in this report dem onstrates, the reduction of fine particles in the eastern U.S. requires a careful bal ance of regional and local controls for
SO 2 , NO X , sources of organic carbon and primary PM 2.5 during both summer and winter.
The (relatively) higher emissions of SO 2 and NO X from regions upwind of MANE-VU as well as the long “reach” of sulfate poll ution requires continued regional control of these fine particle precursors. However , local accumulation of SO 2 -derived sulfate, NO X -derived nitrate, and primary PM (mostly in the form of black carbon/diesel exhaust) can significantly boost urban PM 2.5 levels. Residential wood combustion in rural river valleys can significantly raise PM level s as well and affect rural visibility in
areas near to Class I areas.
The balance between regional and local controls par allels the balance that needs to be achieved between pollutants. The regional co ntribution to fine particle pollution is driven by sulfates and organic carbon, whereas the local contribution to PM 2.5 is derivedPM 2.5 and Regional Haze Air Quality Problems in the MANE -VU Region: A Conceptual Description Page 4-13

from SO 2 , NO X , organic carbon, and primary PM 2.5 (including black carbon/diesel exhaust).
Finally, control strategies which focus on regional SO 2 emissions reductions are needed throughout the summer and winter months, sug gesting that a year-round approach
to control is needed. Urban nonattainment counties with local emissions of NO X and VOC will be driven to reduce these emissions during the summer for ozone benefits, but these same pollutants – as well as primary particul ate emissions – contribute to high
PM 2.5 levels in winter, suggesting that annual controls for all of these pollutants make sense in a multi-pollutant context. Finally, reside ntial wood smoke near Class I areas is clearly a winter-only issue, and further controls m ay be desirable near specific Class I sites where organic carbon is a contributor on the 20 percent worst visibility days that
occur in winter months.
To bring attainment to the current fine particle no nattainment counties and meet reasonable progress goals toward national visibilit y goals, there continues to be a need for more regional SO 2 and NO X reductions coupled with appropriate local SO 2 , NO X , VOC, and primary PM 2.5 (including diesel exhaust) controls where local ac cumulation is shown to add to the regional burden of sulfate and nitrat e PM 2.5 (primarily in winter). These local controls will vary by location and by season, but the regional control of SO 2 and
NO X should be maintained on an annual basis given the contribution of regional sulfate and nitrate to fine particle peaks during both summ er and winter months.PM 2.5 and Regional Haze Air Quality Problems in the MANE -VU Region: A Conceptual Description Page A-1



# Appendix A: Excerpts from EPA Guidance Document, Guidance on the Use of Models and Other Analyses for Demonstrating Attainment of Air Quality Goals for Ozone, PM 2.5 

# , and Regional HazePM 2.5 and Regional Haze Air Quality Problems in the MANE -VU Region: A Conceptual Description Page A-2



## APPENDIX A: EPA GUIDANCE DOCUMENT EXERPT

11.0 How Do I Get Started? - A “Conceptual Descript ion”

A State/Tribe should start developing information to support a modeled attainment demonstration by assembling and reviewing available air quality, emissions and meteorological data. Baseline design values should be calculated at each monitoring site, as described in Section 3. For PM applications, specia ted data should be reviewed to get a sense of what component(s) might be contributing mo st significantly to nonattainment or light extinction. If past modeling has been perform ed, the emission scenarios examined and air quality predictions may also be useful. Rea dily available information should be used by a State/Tribe to develop an initial conceptu al description of the nonattainment or reasonable haze problem in the area which is the fo cus of a modeled demonstration. A conceptual description is instrumental for identify ing potential stakeholders and for developing a modeling/analysis protocol. It may als o influence a State’s choice of air quality model, modeling domain, grid cell size, pri orities for quality assuring and refining emissions estimates, and the choice of initial diag nostic tests to identify potentially effective control strategies. In general, a concept ual description is useful for helping a State/Tribe identify priorities and allocate resourc es in performing a modeled
demonstration.

In this Section, we identify key parts of a conceptu al description. We then present examples of analyses which could be used to describ e each of these parts. We note that initial analyses may be complemented later by addit ional efforts performed by those implementing the protocol.

11.1 What Is A “Conceptual Description”?

A “conceptual description” is a qualitative way of characterizing the nature of an area’s nonattainment or regional haze problem. It is best described by identifying key components of a description. Examples are listed be low. There are 3 different examples. One each for ozone, annual PM 2.5 , and regional haze. The examples are not necessari ly comprehensive. There could be other features of an area’s problem which are important in particular cases. For purposes of illustration la ter in the discussion, we have answered each of the questions posed below. Our responses ap pear in parentheses.

11.1.1 8-Hour Ozone NAAQS 1. Is the nonattainment problem primarily a local o ne, or are regional factors important? (Surface measurements suggest transport of ozone clo se to 84 ppb is likely. There are
some other nonattainment areas not too far distant. )

2. Are ozone and/or precursor concentrations aloft also high? (There are no such measurements.)PM 2.5 and Regional Haze Air Quality Problems in the MANE -VU Region: A Conceptual Description Page A-3

3. Do violations of the NAAQS occur at several monit oring sites throughout the nonattainment area, or are they confined to one or a small number of sites in proximity to
one another? (Violations occur at a limited number of sites, loc ated throughout the area.)

4. Do observed 8-hour daily maximum ozone concentra tions exceed 84 ppb frequently or just on a few occasions? (This varies among the monitors from 4 times up to 12 times per year.)

5. When 8-hour daily maxima in excess of 84 ppb occ ur, is there an accompanying characteristic spatial pattern, or is there a varie ty of spatial patterns? (A variety of patterns is seen.)

6. Do monitored violations occur at locations subje ct to mesoscale wind patterns (e.g., at a coastline) which may differ from the general wind flow? (No.)

7. Have there been any recent major changes in emis sions of VOC or NO X in or near the nonattainment area? If so, what changes have occurr ed? (Yes, several local measures [include a list] belie ved to result in major reductions in VOC [quantify in tons per summer day] have been impleme nted in the last five years. Additionally, the area has seen large regional NO X reductions from the NO X SIP call.)

8. Are there discernible trends in design values or other air quality indicators which have accompanied a change in emissions? (Yes, design values have decreased by about 10% at four sites over the past [x] years.
Smaller or no reductions are seen at three other si tes.)

9. Is there any apparent spatial pattern to the tre nds in design values? (No.)

10. Have ambient precursor concentrations or measur ed VOC species profiles changed? (There are no measurements.)

11. What past modeling has been performed and what do the results suggest? (A regional modeling analysis has been performed. T wo emission scenarios were
modeled: current emissions and a substantial reduct ion in NO X emissions throughout the regional domain. Reduced NO X emissions led to substantial predicted reductions in 8- hour daily maximum ozone in most locations, but cha nges near the most populated area in the nonattainment area in question were small or nonexistent.)

12. Are there any distinctive meteorological measur ements at the surface or aloft which appear to coincide with occasions with 8-hour daily maxima greater than 84 ppb? (Other than routine soundings taken twice per day, there are no measurements aloft. There is no obvious correspondence with meteorologi cal measurements other than daily maximum temperatures are always > 85 F on these days .)PM 2.5 and Regional Haze Air Quality Problems in the MANE -VU Region: A Conceptual Description Page A-4

Using responses to the preceding questions in this example, it is possible to construct an initial conceptual description of the nonattainment area’s ozone problem. First, responses to questions 1 and 11 suggest there is a significan t regional component to the area’s nonattainment problem. Second, responses to question s 3, 4, 7, 8, and 11 indicate there is an important local component to the area’s nonattai nment problem. The responses to questions 4, 5 and 12 indicate that high ozone conc entrations may be observed under several sets of meteorological conditions. The res ponses to questions 7, 8, and 11 suggest that ozone in and near the nonattainment ar ea may be responsive to both VOC
and NO X controls and that the extent of this response may vary spatially. The response to question 6 suggests that it may be appropriate to d evelop a strategy using a model with 12 km grid cells.

The preceding conceptual description implies that t he State/Tribe containing the nonattainment area in this example will need to inv olve stakeholders from other, nearby States/Tribes to develop and implement a modeling/an alysis protocol. It also suggests that a nested regional modeling analysis will be ne eded to address the problem. Further, it may be necessary to model at least several distinct ive types of episodes and additional analyses will be needed to select episodes. Finally, sensitivity (i.e., diagnostic) tests, or other modeling probing tools, will be needed to ass ess the effects of reducing VOC and
NO X emissions separately and at the same time.

11.1.2 Annual PM 2.5 NAAQS 1. Is the nonattainment problem primarily a local o ne, or are regional factors important? (Surface measurements suggest that only design value s in or immediately downwind of the city violate the NAAQS. However, other nearby de sign values come close to the concentration specified in the NAAQS)

2. What is the relative importance of measured prim ary and secondary components of
PM 2.5 measured at sites violating the NAAQS? (Secondary components (i.e., SO 4 , NO 3 , OC) constitute about 80% of the measured mass
of PM 2.5 . There are higher concentrations of primary PM 2.5 in the core urban area compared to the suburbs and more rural areas.)

3. What are the most prevalent components of measur ed PM 2.5 ? (The most important components in ranked order are mass associated with SO 4 , OC and inorganic primary particulate matter (IP)).

4. Does the measured mix of PM components appear to roughly agree with mix of emission categories surrounding the monitoring site s? (No. Relative importance of measured crustal materi al (IP) appears less than what might be inferred from the inventory).

5. Do there appear to be any areas with large gradi ents of primary PM 2.5 in monitored or
unmonitored areas? (Cannot really tell for sources of crustal material until we resolve the precedingPM 2.5 and Regional Haze Air Quality Problems in the MANE -VU Region: A Conceptual Description Page A-5

inventory/monitoring discrepancy. There are no othe r obvious major sources of primary particulate matter).

6. Is there any indication of what precursor might be limiting formation of secondary particulate matter? (No indicator species analyses have been performed. Past analyses performed for ozone-related SIP revisions suggest that ozone in thi s area may be limited by availability of VOC).

7. Do monitored violations occur at locations subje ct to mesoscale wind patterns (e.g., at a coastline) which may differ from the general wind flow? (No.)

8. Have there been any recent major changes in emis sions of PM or its precursors in or
near the nonattainment area? What? (Yes, measures believed to result in major reductio ns in VOC and NO X have been implemented in the last 5 years. Reductions in powe r plant NO X have resulted from the
NO X SIP call and SO 2 emissions reductions have resulted from the nationa l program to reduce acid deposition.)

9. Are there discernible trends in design values or other air quality indicators which have accompanied a change in emissions? (The trend appears to be downward, but the most rec ent air quality data has been higher. Overall, the period of record is insufficiently lon g to tell).

10. Is there any apparent spatial pattern to the tr ends in design values? (No.)

11. What past modeling has been performed and what do the results suggest? (A regional modeling analysis has been performed fo r ozone and PM 2.5 . Two emission
scenarios were modeled: current emissions and a sub stantial reduction in NO X and SO 2 emissions throughout a regional domain. Reduced NO X emissions led to substantial predicted reductions in 8-hour daily maximum ozone in most locations. Modeled SO 2 reductions from the CAIR rule had a strong impact o n sulfate concentrations)

12. Are there any distinctive meteorological measur ements at the surface or aloft which appear to coincide with occasions with PM 2.5 concentrations in excess of 15.0 : g/m 3 ? (Other than routine soundings taken twice per day, there are no measurements aloft. There is no obvious correspondence with meteorologi cal measurements other than daily maximum temperatures are often > 85F on days with th e highest PM 2.5 observations.)

13. Do periods with high measured particulate matte r or components of particulate matter appear to track each other or any other measured po llutant? (There appears to be some correspondence between me asured high concentrations of
SO 4 and ozone).PM 2.5 and Regional Haze Air Quality Problems in the MANE -VU Region: A Conceptual Description Page A-6

Using responses to the preceding questions in this example, it is possible to construct an initial conceptual description of the nonattainment area’s ozone problem. First, responses to questions 1, 2 and 3 suggest there is a signific ant regional component to the area’s nonattainment problem. Second, responses to question s 1 and 3 indicate there is a local component to the problem. The responses to question s 11,12 and 13 suggest that there may be a link between reducing ozone and reducing p articulate matter. Thus, it may be appropriate to assess effects of previously committ ed to strategies to reduce ozone and national PM control measures before simulating addit ional control measures. The responses to questions 4 and 5 suggest that it is p remature to determine whether a “local area analysis” will be needed. The response to ques tion 7 suggests that it may not be necessary to model with very small grid cells, at l east for the secondary components of
PM 2.5

.

The preceding conceptual description implies that t he State containing the nonattainment area in this example will need to involve stakehold ers from other, nearby States to develop and implement a modeling/analysis protocol. It also suggests that a nested regional modeling analysis will be needed to addres s the problem.

11.1.3 Example reasonable progress application 1. What components of particulate matter appear to have high concentrations on days with poor visibility? (Mass associated with SO 4 and coarse particulate matter (CM) seem to have the highest concentrations on most such days).

2. What are typical values for the humidity adjustm ent factor during the times of year when most of the days with poor visibility occur? (Typical values appear to be about “4.0").

3. Does visibility appear to track well among nearb y Class I areas? (Yes, but not always).

4. Does poor visibility seem to occur under any spe cific meteorological conditions? (This information is not readily available).

5. Does poor visibility seem to coincide with high observed concentrations of any particular other pollutant? (There seems to be some correspondence with high re gional ozone concentrations)

6. What components of particulate matter appear to have relatively high concentrations on days with good visibility? (Coarse particulate matter and OC)

7. What are typical values for the humidity adjustm ent factor during times of year when most of the days with good visibility occur? (About “2.3")PM 2.5 and Regional Haze Air Quality Problems in the MANE -VU Region: A Conceptual Description Page A-7

8. Does good visibility appear to occur under any s pecific meteorological conditions? (Don’t know.)

Answers to the preceding questions suggest that str ategies to reduce sulfate concentrations and, perhaps, regional ozone concent rations might be effective in reducing light extinction on days when visibility is current ly poor. The responses suggest that a strategy which focuses on this alone should first b e tried for the days with good visibility as well. Even though sulfate concentrations appear low on such days, the fact that sulfates scatter light efficiently (see Equation (6.1)) and relative humidity is still high enough to enhance this effect is worth considering. Responses suggest that further meteorological analyses would be worthwhile prior to selecting str ategies to simulate with a resource intensive regional model.

It should be clear from the preceding examples that the initial conceptual description of an area’s nonattainment problem draws on readily av ailable information and need not be detailed. It is intended to help launch development and implementation of a modeling/analysis protocol in a productive directio n. It will likely be supplemented by subsequent, more extensive modeling and ambient ana lyses performed by or for those implementing the modeling/analysis protocol discuss ed in Section 12.0.

Questions like those posed in Section 11.1 can be ad dressed using a variety of analyses ranging in complexity from an inspection of air qua lity data to sophisticated mathematical analyses. We anticipate the simpler an alyses will often be used to develop the initial conceptual description. These will be f ollowed by more complex approaches or by approaches requiring more extensive data bases a s the need later becomes apparent. These analyses are intended to channel resources av ailable to support modeled attainment demonstrations onto the most productive paths possi ble. They will also provide other pieces of information which can be used to reinforc e conclusions reached with an air quality model, or cause a reassessment of assumptio ns made previously in applying the model. As noted in Section 7, corroboratory analyses should be used to help assess whether a simulated control strategy is sufficient to meet the NAAQS.PM 2.5 and Regional Haze Air Quality Problems in the MANE -VU Region: A Conceptual Description Page B-1



# Appendix B: Monitoring Data from Class I sites in MANE-VU

Below are figures that were developed by Tom Downs of the Maine Department of Environmental Protection. These figures represe nt baseline monitoring data for the Class I sites (and Washington DC) based on IMPROVE monitoring network data using the EPA approved “default” algorithm for calculating reconstructed extinction and estimating natural background conditions. These st atistics may need to be recreated using the alternative methodology approved by the I MPROVE steering committee and adopted by the MANE-VU states. Glide path graphs w ere created on the VIEWS website ( http://vista.cira.colostate.edu/views/ ) using the Annual Summary Trends tool. Seasonal graphs were created from data downloaded from the V IEWS website using the Annual Summary Composition tool and should be updated to in clude 2004 data for a complete description of regional haze baseline data.PM 2.5 and Regional Haze Air Quality Problems in the MANE -VU Region: A Conceptual Description Page B-2



## APPENDIX B: MONITORING DATA FROM CLASS I SITES IN MANE-VU

Figure B-1. Monitoring Data from Acadia NP, ME

April 26, 1995 - Teflon filter was increased from 2.2 sq. cm to 3.5 sq. cm



### Extinction Trendsdv 

### Deciview (dv) TrendsPM 2.5 and Regional Haze Air Quality Problems in the MANE -VU Region: A Conceptual Description Page B-3

Figure B-2. Monitoring Data from Brigantine, ME



### Extinction Trendsdv 

### Deciview (dv) TrendsPM 2.5 and Regional Haze Air Quality Problems in the MANE -VU Region: A Conceptual Description Page B-4

Figure B-3. Monitoring Data from Great Gulf, NH



### Extinction Trendsdv 

### Deciview (dv) TrendsPM 2.5 and Regional Haze Air Quality Problems in the MANE -VU Region: A Conceptual Description Page B-5

Figure B-4. Monitoring Data from Lye Brook, VT



### Extinction Trendsdv 

### Deciview (dv) TrendsPM 2.5 and Regional Haze Air Quality Problems in the MANE -VU Region: A Conceptual Description Page B-6

Figure B-5. Monitoring Data from Moosehorn, ME



### Extinction Trendsdv 

### Deciview (dv) TrendsPM 2.5 and Regional Haze Air Quality Problems in the MANE -VU Region: A Conceptual Description Page B-7

Figure B-6. Monitoring Data from Washington, DC



### Extinction Trendsdv 

### Deciview (dv) TrendsPM 2.5 and Regional Haze Air Quality Problems in the MANE -VU Region: A Conceptual Description Page B-8

Figure B-7. 20% Worst and Best 2000-2003 Visibilit y Days at Acadia NP, ME

Seasonal Analysis of the 20% Best 2000-2003 Visibility Days at Acadia National Park

0 1 2 3 4 5 6 7 8 9 10

Sulfate Nitrate Org Carbon Elem Carbon Soil Coarse MassExtinction (Mm-1) Winter - 19 days

Summer - 15 days

Spring - 24 days

Fall - 35 days Created by Tom Downs, Maine DEP-BAQ - 11/02/2006
/2006 Seasonal Analysis of the 20% Worst 2000-2003 Visibility Days at Acadia National Park

0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85

Sulfate Nitrate Org Carbon Elem Carbon Soil Coarse MassExtinction (Mm-1) Winter - 16 days

Summer - 39 days

Spring - 17 days

Fall - 23 days Created by Tom Downs, Maine DEP-BAQ - 11/02/2006
/2006PM 2.5 and Regional Haze Air Quality Problems in the MANE -VU Region: A Conceptual Description Page B-9

Figure B-8. 20% Worst and Best 2000-2003 Visibilit y Days at Brigantine, NJ

Seasonal Analysis of the 20% Best 2000-2003 Visibility Days at Brigantine, NJ

0 2 4 6 8 10 12 14 16 18 20

Sulfate Nitrate Org Carbon Elem Carbon Soil Coarse MassExtinction (Mm-1) Winter - 20 days

Summer - 13 days

Spring - 21 days

Fall - 33 days Created by Tom Downs, Maine DEP-BAQ - 11/02/2006
/2006 Seasonal Analysis of the 20% Worst 2000-2003 Visibility Days at Brigantine, NJ

0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160

Sulfate Nitrate Org Carbon Elem Carbon Soil Coarse MassExtinction (Mm-1) Winter - 15 days

Summer - 39 days

Spring - 15 days

Fall - 21 days Created by Tom Downs, Maine DEP-BAQ - 11/02/2006
/2006PM 2.5 and Regional Haze Air Quality Problems in the MANE -VU Region: A Conceptual Description Page B-10

Figure B-9. 20% Worst and Best 2000-2003 Visibilit y Days at Great Gulf, NH

Seasonal Analysis of the 20% Best 2000-2003 Visibility Days at Great Gulf, NH

0 1 2 3 4 5 6 7

Sulfate Nitrate Org Carbon Elem Carbon Soil Coarse MassExtinction (Mm-1) Winter - 28 days

Summer - 7 days

Spring - 17 days

Fall - 29 days Created by Tom Downs, Maine DEP-BAQ - 11/02/2006
/2006 Seasonal Analysis of the 20% Worst 2000-2003 Visibility Days at Great Gulf, NH

0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85

Sulfate Nitrate Org Carbon Elem Carbon Soil Coarse MassExtinction (Mm-1) Winter - 9 days

Summer - 39 days

Spring - 13 days

Fall - 23 days Created by Tom Downs, Maine DEP-BAQ - 11/02/2006
/2006PM 2.5 and Regional Haze Air Quality Problems in the MANE -VU Region: A Conceptual Description Page B-11

Figure B-10. 20% Worst and Best 2000-2003 Visibili ty Days at Lye Brook, VT

Seasonal Analysis of the 20% Best 2000-2003 Visibility Days at Lye Brook, VT

0 1 2 3 4 5 6

Sulfate Nitrate Org Carbon Elem Carbon Soil Coarse MassExtinction (Mm-1) Winter - 29 days

Summer - 11 days

Spring - 22 days

Fall - 24 days Created by Tom Downs, Maine DEP-BAQ - 11/02/2006
/2006 Seasonal Analysis of the 20% Worst 2000-2003 Visibility Days at Lye Brook, VT

0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110

Sulfate Nitrate Org Carbon Elem Carbon Soil Coarse MassExtinction (Mm-1) Winter - 12 days

Summer - 37 days

Spring - 17 days

Fall - 23 days Created by Tom Downs, Maine DEP-BAQ - 11/02/2006
/2006PM 2.5 and Regional Haze Air Quality Problems in the MANE -VU Region: A Conceptual Description Page B-12

Figure B-11. 20% Worst and Best 2000-2003 Visibili ty Days at Moosehorn, ME

Seasonal Analysis of the 20% Best 2000-2003 Visibility Days at Moosehorn, ME

0 1 2 3 4 5 6 7 8 9

Sulfate Nitrate Org Carbon Elem Carbon Soil Coarse MassExtinction (Mm-1) Winter - 15 days

Summer - 18 days

Spring - 21 days

Fall - 36 days Created by Tom Downs, Maine DEP-BAQ - 11/02/2006
/2006 Seasonal Analysis of the 20% Worst 2000-2003 Visibility Days at Moosehorn, ME

0 5 10 15 20 25 30 35 40 45 50 55 60 65 70

Sulfate Nitrate Org Carbon Elem Carbon Soil Coarse MassExtinction (Mm-1) Winter - 20 days

Summer - 41 days

Spring - 14 days

Fall - 18 days Created by Tom Downs, Maine DEP-BAQ - 11/02/2006
/2006PM 2.5 and Regional Haze Air Quality Problems in the MANE -VU Region: A Conceptual Description Page B-13

Figure B-12. 20% Worst and Best 2000-2003 Visibili ty Days at Washington, D.C.

Seasonal Analysis of the 20% Best 2000-2003 Visibility Days at Washington, D.C.

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28

Sulfate Nitrate Org Carbon Elem Carbon Soil Coarse MassExtinction (Mm-1) Winter - 22 days

Summer - 9 days

Spring - 26 days

Fall - 31 days Created by Tom Downs, Maine DEP-BAQ - 11/02/2006
/2006 Seasonal Analysis of the 20% Worst 2000-2003 Visibility Days at Washington, D.C.

0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150

Sulfate Nitrate Org Carbon Elem Carbon Soil Coarse MassExtinction (Mm-1) Winter - 16 days

Summer - 42 days

Spring - 14 days

Fall - 20 days Created by Tom Downs, Maine DEP-BAQ - 11/02/2006
/2006PM2.5and Regional Haze Air Quality Problems in the MANE-VU Region: A Conceptual DescriptionPage B-14Figure B-13. 20% Best 2000-2003 Visibility Days Speciated Contributions to ExtinctionWashington D.C.176 Mm-1(22 km/29.0 dv)Brigantine159 Mm-1(25 km/27.9 dv)Lye Brook108 Mm-1(38 km/23.9 dv)Great Gulf(Presidential Range)94 Mm-1(45 km/22.5 dv)Acadia91 Mm-1(44 km/22.4 dv)Moosehorn(Roosevelt Campobello)82 Mm-1(48 km/21.4 dv)Moosehorn(Roosevelt Campobello)82 Mm-1(48 km/21.4 dv)20% Worst VisibilitySpeciated Contributions toExtinction (2000-2003 except forGreat Gulf 2001-2003)SiteSulfateNitrateOrg CElem CSoilCoarse MassAcadia7291150.62Moosehorn7081450.53Lye Brook7291250.62Brigantine68111350.64Washington DC61141570.72Great Gulf7631340.63percent contributon to particle extinctionExtinction = 3*f(RH)*sulfate(f) +1.29*Nitrate(f) + 4*1.4*OC(f) + 10* elementalcarbon (f) + 1* soil(f) +0.6 * coarse massCreated by Tom Downs,Maine DEP-BAQ 12/13/2005PM2.5and Regional Haze Air Quality Problems in the MANE-VU Region: A Conceptual DescriptionPage B-15Figure B-14. 20% Best 2000-2003 Visibility Days Speciated Contributions to ExtinctionWashington D.C.47.3 Mm-1(70 km/17.3 dv)Brigantine30.3 Mm-1(101 km/13.8 dv)Lye Brook8.8 Mm-1(215 km/6.1 dv)Great Gulf(PresidentialRange)11.3 Mm-1(189 km/7.4 dv)Acadia12.8 Mm-1(175 km/8.1 dv)20% Best VisibilitySpeciated Contributions toExtinction (2000-2003 exceptfor Great Gulf 2001-2003)SiteSulfateNitrateOrg CElem CSoilCoarse MassAcadia60918716Moosehorn54922718Lye Brook571414716Brigantine5313147112Washington DC4917161215Great Gulf56918818percent contributon to particle extinctionCreated by Tom Downs,Maine DEP-BAQ 12/13/2005Moosehorn(Roosevelt Campobello)13.9 Mm-1(169 km/8.6 dv)Moosehorn(Roosevelt Campobello)13.9 Mm-1(169 km/8.6 dv)PM 2.5 and Regional Haze Air Quality Problems in the MANE -VU Region: A Conceptual Description Page C-1



# Appendix C: Additional Considerations for PM 2.5



# Air Quality ManagementPM 2.5 and Regional Haze Air Quality Problems in the MANE -VU Region: A Conceptual Description Page C-2



## APPENDIX C: ADDITIONAL CONSIDERATIONS FOR
PM 2.5 

## AIR QUALITY MANAGEMENT

C.1. Averaging times and data interpretation
In analyzing the chemical data available for interp reting the air quality event of August 2002, it is important to point out that the use of different averaging times can have a profound effect on our understanding of the progression of any specific episode. Many subtleties of synoptic-scale meteorology and a tmospheric chemistry are “aliased out” of data sets with temporal resolution greater than 3-6 hours. These effects are demonstrated in Figure C-1 which show fine aerosol T EOM data from New Haven for the “episode” period August 10-16, 2002. In these figures, the hourly TEOM values have been aggregated into 3-, 6- and 24-hour mean values . Average concentrations are inversely proportional to the length of the averagi ng period and the ratio of peak hourly concentration within a daily average ranges from ab out 1.5 to 1.75 for this episode.

Figure C-1. Effects of averaging times (or tempora l resolution) on time series information

Figure 5.6(a) Unfiltered (hourly) TEOM data from Ne w Haven, Conn.

0 10 20 30 40 50 60 70 80 90

8 / 1 0 / 0 2 0 :0 0 8/11 / 0 2 0 :0 0 8/1 2 / 0 2 0: 0 0 8/13/02 0:

0 0 8 / 14/02 0:

0 0 8/1 5 / 0 2 0 :0 0 8/16/02 0:00Fine Aerosol Mass (ug/m3) Figure 5.6(b) New Haven, Conn. TEOM data with a 3-h our filter.

0 10 20 30 40 50 60 70 80 90

8 / 1 0 / 0 2 0 :0 0 8 / 1 1 / 0 2 0 :0 0 8/12 / 0 2 0 :0 0 8/13 / 0 2 0:0 0 8/1 4 / 0 2 0

: 00 8/15/02 0:00 8/16/02 0:00Fine Aerosol Conc. (ug/m3)

Figure 5.6(c) New Haven, Conn. TEOM data with a 6-h our filter.

0 10 20 30 40 50 60 70 80 90

8/10 / 02 0:00 8/11

/02 0: 0 0 8/12 /02 0: 0 0 8/13/0

2 0:0 0 8/14/02 0:00 8/15/02 0:00 8/16 / 02 0:00Fine Aerosol Conc. (ug/m3) Figure 5.6(d) New Haven, Conn. TEOM data with a 24- hour filter.

0 10 20 30 40 50 60 70 80 90

8/10/02 0:00 8

/ 1 1/02 0:00 8/12

/ 0 2 0:00 8 / 1 3 / 0 2 0 :0 0 8 / 1 4/02 0:0

0 8/15 / 02 0:00 8/16

/02 0: 0 0Fine Aerosol Conc. (ug/m3)PM 2.5 and Regional Haze Air Quality Problems in the MANE -VU Region: A Conceptual Description Page C-3



### C.2. Rural versus urban PM 2.5 

### mass Comparison of PM 2.5 concentrations from rural areas with those from urban/suburban areas can add significantly to our u nderstanding of the impact on air quality of both urban sources and of medium to long -range fine aerosol transport. To assist with this approach, data from 10 pairs of ru ral and urban/suburban FRM sites throughout the MANE-VU region were selected and ana lyzed.
Table C-1 shows basic site description information including the approximate, straight-line distance between the site pairs.
Due to the difficulty in finding a significant numb er of urban-rural site pairs that operated on the same sampling schedule, sites with a mixture of schedules were used to insure samples representative of the entire MANE-VU region. As a result, three of the 20 sites employed an everyday schedule while two sites sampled every sixth day (the remainder sampled every third day). Data from the three everyday sites were edited so as to include data from the 1-in-3 schedule only. In all, a total of 1098 data points were possible from the 10 site pairs for 2002. Of the 1 098 possible point-pairs, 951 (87%) were valid and were used in this analysis.

Table C-1. MANE-VU urban-rural site pair informati on

State Site No City Land use Location type Longitude Latit ude Inter-site
Distance (mi) DE 100051002 Agricultural Rural -75.55560 38.98470 DE 100010002 Seaford Residential Suburban -75.61310 38.64 440 24.0

MA 250154002 Ware Forest Rural -72.33472 42.29833 MA 250130016 Springfield Commercial Urban & Center City -72.59140 42.10890 17.6

MD 240030014 Agricultural Rural -76.65310 38.90250 MD 245100049 Baltimore Residential Urban & Center City - 76.63750 39.26170 25.2

ME 230052003 Cape Elizabeth Residential Rural -70.20778 4 3.56083 ME 230010011 Lewiston Commercial Urban & Center City -70 .21500 44.08940 37.0

NJ 340218001 Agricultural Rural -74.85470 40.31500 NJ 340210008 Trenton Residential Urban & Center City -74 .76360 40.22220 7.7

NY 360010012 Albany Agricultural Rural -73.75690 42.68070 NY 360930003 Schenectady Residential Suburban -73.94020 4 2.79960 11.7

NY 361030001 Babylon Commercial Rural -73.42030 40.74580 NY 360590013 Bethpage Residential Suburban -73.49060 40.7 6080 3.3

NY 360130011 Westfield Agricultural Rural -79.60250 42.29 080 PA 420490003 Erie Commercial Suburban -80.03860 42.14180 2 2.2

PA 420030093 Residential Rural -80.02080 40.60720 PA 420030021 Pittsburgh Residential Suburban -79.94140 40 .41360 14.0

PA 420290100 Commercial Rural -75.76860 39.83440
DE 100031012 Newark Residential Suburban -75.76170 39.69190 10.0PM 2.5 and Regional Haze Air Quality Problems in the MANE -VU Region: A Conceptual Description Page C-4

As expected, urban/suburban areas, with their rich supply of emission sources, almost always reported higher concentrations than t heir nearby sister sites in rural areas. Of the 951 valid data pairs, 660 showed higher urba n/suburban levels while 291 cases showed higher rural levels.
One interesting aspect of the 2002 urban-rural data concerns the pattern in seasonal differences between such site pairs. Figur e C-2 shows the difference (urbanrural) between the 10 site pairs as a time series.

Although some rural-to-urban seasonal differences a re to be expected, the variation in the magnitude of this difference is su rprising. In the warm/hot months, the
mean rural/urban difference amounts to no more than ~0.7 μg/m 3 (based on a best-fit 2 nd order polynomial curve), which is a relatively smal l differential. However, during the
cool/cold months that difference climbs to almost 4 μg/m 3 , demonstrating a total annual seasonal variation of at least 3 μg/m 3 . Because the mean annual concentration of all sit es is 12.6 μg/m 3 , an annual variation of 3 μg/m 3 becomes significant.
One explanation for the observed seasonal variation concerns the temporal distribution of local and transported emissions. I n the summertime, MANE-VU sites repeatedly experience sulfate events due to transpo rt from regions to the south and west. During such events, rural and urban sites throughou t MANE-VU record high (i.e., >15 μg/m 3 ) daily average PM 2.5 concentrations. During summer stagnation events, atmospheric ventilation is poor and local emissions are added to the transported burden with the result that concentrations throughout the region (rural and urban) are relatively Figure C-2. Difference in FRM data between 10 urba n-rural site pairs for 2002

-2.0 -1.0 0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0

1/2/2002 2/1/2002 3/3/ 200 2 4/2/ 200 2 5/2/ 200 2 6/1/2002 7/1/2002 7/31/2002 8/30/2002 9/29/2002 10/29/2002 11/28/2002 12/28/2002Urban-Rural Conc. (ug/m3)PM 2.5 and Regional Haze Air Quality Problems in the MANE -VU Region: A Conceptual Description Page C-5

uniform. There are enough of these events to drive the urban-rural difference down to less than 1 μg/m 3 during warm/hot months.
During the wintertime, strong local inversions freq uently trap local emissions during the overnight and early morning periods, res ulting in elevated urban concentrations. Rural areas experience those same inversions but have relatively fewer
local sources so that wintertime concentrations in rural locations tend to be lower than those in nearby urban areas. Medium and long-range fine aerosol transport events do occur during the winter but at a much reduced rate compared to summertime. So, it is the interplay between local and distant sources as well as meteorological conditions that
drive the observed seasonal urban-rural difference in FRM concentrations.



### C.3. Seasonal relationship between PM 2.5 

### and NO X Because nitrogen oxides (NO X ) can be a good indicator of regional as well as local emissions, NO X data for the MANE-VU region was downloaded from USE PA’s AQS. Ultimately, data from six widely separated MANE -VU NO X sites were selected (one site each in CT, DC, MA, NH, PA and VT). Sites were selected both for high data capture rates and geographic location. The NO X data were then aggregated into regional averages on a daily basis and compared to PM 2.5 FRM data from 34 “everyday” sampling sites (which were also averaged on a regional basis ).
During 2002, there were virtually no periods when r egional mean PM 2.5 concentrations rose above 20 μg/m 3 and were not accompanied by rising (or already high) NO X concentrations. However, as seen in Figure C-3, N O X concentrations vary widely on an annual basis and tend to occur out-of- sync with fine particle concentrations.
Although the min/max extremes of these two pollutan ts are offset in time, they are highly correlated during some parts of the year. F or example, Figure C-4 shows the regional PM 2.5 and NO X data for the coldest (Jan., Feb., Nov., and Dec.) a nd hottest (May, June, July and Aug.) seasons of 2002. Winter time NO X and PM 2.5 concentrations are rather well correlated (r 2 =0.67) while summertime concentrations are not at a ll linked. This dichotomy can be explained by several coincide nt effects including: 1) reduced UV radiation during cold months (which prevents photol ysis of NO 2 to O 3 ); 2) the increase in space heating requirements from stationary sources (which preferentially increases morning NO X emissions; increased NO X emissions due to “cold-start” mobile source engines and 3) decreased mixing height depths due t o reduced solar input (which allows morning concentrations to build quickly). Note tha t the Spring/Fall PM 2.5 vs. NO X correlation (not shown) lies about mid-way between the winter/summer values shown in Figure C-4.PM 2.5 and Regional Haze Air Quality Problems in the MANE -VU Region: A Conceptual Description Page C-6

Figure C-3. Regional PM 2.5 and NO X in 2002

0 20 40 60 80 100 120 140 160

1/ 1/02 2/

1/02 3/1/02 4/1/02 5/1/02 6/1/02 7/ 1/02 8/

1/02 9/1/02 10

/1/02 11/1/02 12/1/02NOx (ppbv) PM2.5 (ug/m3) Mean Reg. NOx ( 6 sites)

Mean Reg. PM2.5 (34 FRM sites)

Figure C-4. PM 2.5 vs. NO X correlation by season

MANE-VU Regional PM 2.5 vs. Regional NO x - 2002

y = 4.08x - 4.65

R 2 = 0.67

y = 0.13x + 18.23

R 2 = 0.05

0 30 60 90 120 150

0 10 20 30 40 50 60 70

PM 2.5 Conc. (ug/m 3 )NOx Conc. (ppb) Winter Months

Summer Months MANE-VU Regional PM 2.5 vs. Regional NO x - 2002

y = 4.08x - 4.65

R 2 = 0.67

y = 0.13x + 18.23

R 2 = 0.05

0 30 60 90 120 150

0 10 20 30 40 50 60 70

PM 2.5 Conc. (ug/m 3 )NOx Conc. (ppb) Winter Months

Summer MonthsPM 2.5 and Regional Haze Air Quality Problems in the MANE -VU Region: A Conceptual Description Page C-7