Urban Tree Cover: An Innovative Urban Tree Cover: An Innovative Strategy for Air Quality PlanningStrategy for Air Quality Planning

David J. NowakDavid J. Nowak

USDA Forest ServiceUSDA Forest Service

Northeastern Research StationNortheastern Research Station

Syracuse, NYSyracuse, NY

GoalGoal

Use urban tree Use urban tree cover and its cover and its management as management as a strategy to a strategy to reduce ozone reduce ozone with State with State Implementation Implementation PlansPlans

OverviewOverview

History – How we got hereHistory – How we got here Why Ozone?Why Ozone? Why Trees?Why Trees? SIPs – brief overviewSIPs – brief overview

History – How we got hereHistory – How we got here

1992 NUCFAC grant 1992 NUCFAC grant – Feasibility of funding urban tree management Feasibility of funding urban tree management

based on the benefits of urban treesbased on the benefits of urban trees

1992 NUCFAC Grant1992 NUCFAC Grant

Can we convert benefits to Can we convert benefits to dollars?dollars?– COCO22 and Carbon and Carbon

Global warmingGlobal warming

– Air pollutantsAir pollutants Commodity trading of NOCommodity trading of NOx x and and

SOSOxx

Final ResultFinal Result

Ozone reduction by trees had the greatest Ozone reduction by trees had the greatest funding potentialfunding potential

EPA seemed interested EPA seemed interested – Regulatory programs termed “directionally Regulatory programs termed “directionally

sound”sound”

1995 NUCFAC Grant1995 NUCFAC Grant

Quantify the effect of urban trees on ozoneQuantify the effect of urban trees on ozone– Urban forest field survey Urban forest field survey

NYC, Philadelphia, Baltimore, BostonNYC, Philadelphia, Baltimore, Boston Cover and composition studyCover and composition study

– Used and improved “EPA” modelsUsed and improved “EPA” models Updated cover data, VOC emissions data, deposition dataUpdated cover data, VOC emissions data, deposition data NYS DEC Division of Air Resources NYS DEC Division of Air Resources

– Modeling workModeling work

U.S. East Coast Study-1995U.S. East Coast Study-1995

Increased tree cover from 20% Increased tree cover from 20% to 40% in urban cellsto 40% in urban cells– Demonstrated a measurable Demonstrated a measurable

impact on ozoneimpact on ozone

(Nowak, Civerolo, Rao, Sistla, Luley and Crane, 2000)

1995 NUCFAC Grant1995 NUCFAC Grant

Met with EPAMet with EPA– Presented the East Coast study (w/ NYS DEC)Presented the East Coast study (w/ NYS DEC)

EPA appreciative of research but:EPA appreciative of research but:– Needed data specific to one non-attainment Needed data specific to one non-attainment

area (NYC) area (NYC)

What Happened?What Happened?

NYS has decided to wait to submit a request NYS has decided to wait to submit a request to the EPA – Jan 2002to the EPA – Jan 2002

No reason to submit at that pointNo reason to submit at that point– Already acceptedAlready accepted– Next SIP callNext SIP call

Latest MeetingsLatest Meetings Summer 2002: Met with EPA Administrator Summer 2002: Met with EPA Administrator

Christine Todd Whitman to discuss urban Christine Todd Whitman to discuss urban tree issuestree issues– Mike D’ErricoMike D’Errico– Roni Olizo Roni Olizo

Feb. 2003: Met with EPA StaffFeb. 2003: Met with EPA Staff– Maryland came on board (work also on-going in Maryland came on board (work also on-going in

Houston)Houston)– Defined and discussed a series of regulatory Defined and discussed a series of regulatory

issuesissues– Developed paper on issuesDeveloped paper on issues

April 2004: Meeting with State Foresters and April 2004: Meeting with State Foresters and Air Quality personnelAir Quality personnel

OzoneOzone VOC’s and NOVOC’s and NOxx are precursors are precursors Highest under high temperatures during the dayHighest under high temperatures during the day No point source No point source

– So control strategy is typically aimed at VOC and So control strategy is typically aimed at VOC and NONOxx emission reductions emission reductions

Why Ozone? Why Ozone? Significant effects on human health, plants Significant effects on human health, plants

and environmental quality:and environmental quality:

Why Ozone?Why Ozone? Persistent problemPersistent problem Many areas still in non-attainmentMany areas still in non-attainment

– 159 million people affected159 million people affected– 474 counties or parts of county in non-attainment474 counties or parts of county in non-attainment

State Nonattainment Area Name Counties Classification MaximumAttainment Date

(from June 1, 2004)

Connecticut Greater Connecticut, CT Hartford; New London Tolland; Windham Litchfield

Moderate June 2010

New York-N. New Jersey-Long Island, NY-NJ-CT

Fairfield; Middlesex New Haven

Moderate June 2010

Maine Portland, ME Cumberland (P); Sagadahoc York (P); Androscoggin (P)

Marginal June 2007

Hancock, Knox, Lincoln and Waldo Cos, ME Knox (P); Lincoln (P)Hancock (P); Waldo (P)

Basic June 2009

Massachusetts Boston-Lawrence-Worcester (E. MA), MA Barnstable; Bristol; Dukes Essex; Middlesex; Nantucket Norfolk; Plymouth; Suffolk Worcester

Moderate June 2010

Springfield (Western MA), MA Berkshire; Franklin ; Hamden Hampshire

Moderate June 2010

New Hampshire Boston-Manchester-Portsmouth (SE), NH Hillsborough (P); Merrimack (P); Rockingham (P)

Strafford (P)

Moderate June 2010

Rhode Island Providence (All RI), RI Bristol; Kent; Newport Providence; Washington

Moderate June 2010

Vermont entire state is attainment

Non Attainment – EPA Region 1 Non Attainment – EPA Region 1

State Nonattainment Area Name Counties Classification MaximumAttainment Date

(from June 1, 2004)

Non Attainment – EPA Region 2Non Attainment – EPA Region 2

New Jersey New York-N. New Jersey-Long Island, NY-NJ-CT Bergen; Essex; Hudson Hunterdon; Middlesex Monmouth; Morris; PassaicSomerset; Sussex ; Union Warren

Moderate June 2010

Philadelphia - Wilmington, Atlantic City, PA-DE-MD-NJ

Atlantic; Cape May; Burlington; Camden Cumberland; Gloucester Mercer; Salem; Ocean

Moderate June 2010

New York Jamestown, NY Chautauqua Basic June 2009

Buffalo-Niagara Falls, NY Erie; Niagara Basic June 2009

Rochester, NY Genesee; Livingston ; Monroe; Ontario; Orleans; Wayne

Basic June 2009

Syracuse, NY Cayuga; Madison; Onondaga Oswego

Unclassifiable

Jefferson Co, NY Jefferson Moderate June 2010

Essex Co, NY (Whiteface Mountain) Essex (P) Basic June 2009

Albany-Schenectady-Troy, NY

Albany; Greene; Montgomery Rensselaer; Saratoga Schenectady; Schoharie

Basic June 2009

New York-N. New Jersey-Long Island, NY-NJ-CT Bronx ; Kings; Nassau; New York; Queens; Richmond; Rockland;Suffolk; Westchester

Moderate June 2010

Poughkeepsie, NY Dutchess; Putnam; Orange Moderate June 2010

Virginia Norfolk-Virginia Beach-Newport News (Hampton Roads),VA

City of Chesapeake; City of Hampton; James City; City of Newport News; City of Norfolk; City of Poquoson ; City of Portsmouth; City of Suffolk; City of Virginia Beach; City of Williamsburg; York; Gloucester; Isle of Wight

Marginal June 2007

Richmond-Petersburg, VA Charles City; Chesterfield; City of Colonial Heights; Hanover; Henrico ;City of Hopewell; City of Richmond; City of Petersburg; Prince George

Moderate June 2010

Washington, DC-MD-VA Alexandria City; Arlington; Fairfax City; Fairfax; Falls Church City; Loudoun; Manassas City; Manassas Park CityPrince William

Moderate June 2010

Fredricksburg, VA Spotsylvania; Stafford; City of Fredericksburg Moderate June 2010

Roanoke, VA Botetourt; Roanoke; City of Roanoke; City of Salem Basic Dec 2007

Madison and Page Cos (Shenandoah National Park),VA

Page (P); Madison (P) Basic June 2009

Frederick Co, VA Frederick; City of Winchester Basic Dec 2007

West Virginia

Charleston, WV Kanawha Putnam Basic June 2009

Huntington-Ashland- KY-WV Cabell; Wayne Basic June 2009

Parkersburg-Marietta, OH-WV Wood Basic June 2009

Steubenville-Weirton, OH-WV Brooke; Hancock Basic June 2009

Wheeling, OH-WV Marshall; Ohio Basic June 2009

Berkeley & Jefferson, WV Berkeley ; Jefferson Basic Dec 2007

State Nonattainment Area Name Counties Classification

MaximumAttainment Date

(from June 1, 2004)

Non Attainment – EPA Region 3 Non Attainment – EPA Region 3

Delaware Philadelphia - Wilmington, Atlantic City, PA-DE-MD-NJ

Kent; New Castle; Sussex Moderate June 2010

DC Washington, DC-MD-VA District of Columbia Moderate June 2010

Maryland Baltimore, MD Anne Arundel; Baltimore City; Baltimore Carroll; Harford; Howard

Moderate June 2010

Kent and Queen Anne’s Cos, MD Kent; Queen Anne’s Moderate June 2010

Philadelphia - Wilmington, Atlantic City, PA-DE-MD-NJ

Cecil Moderate June 2010

Washington, DC-MD-VA Calvert; Charle; Frederic; MontgomeryPrince George’s

Moderate June 2010

Washington Co, (Hagerstown), MD Washington Basic Dec 2007

Pennsylvania York, PA Adams; York Basic June 2009

Allentown-Bethlehem-Easton, PA Carbon; Lehigh; Northampton Basic June 2009

Altoona, PA Blair Basic June 2009

Erie, PA Erie Basic June 2009

Franklin Co, PA Franklin Basic June 2009

Greene Co, PA Greene Basic June 2009

Harrisburg-Lebanon-Carlisle, PA Cumberland; Dauphin; Lebanon; Perry Basic June 2009

Johnstown, PA Cambria Basic June 2009

Lancaster, PA Lancaster Moderate June 2010

Philadelphia - Wilmington, Atlantic City, PA-DE-MD-NJ

Bucks; Chester; Delaware; Montgomery Philadelphia

Moderate June 2010

Pittsburgh-Beaver Valley, PA Allegheny; Armstrong; Beaver; Butler; Fayette Washington; Westmoreland

Basic June 2009

Reading, PA Berks Basic June 2009

Youngstown-Warren-Sharon, OH-PA

Mercer Basic June 2009

Scranton-Wilkes-Barre, PA Lackawanna; Luzerne; Monroe; Wyoming Basic June 2009

Clearfield and Indiana, PA Clearfield; Indiana Basic June 2009

State College, PA Centre Basic June 2009

Tioga Co, PA Tioga Basic June 2009

Why Ozone?Why Ozone?

States in Non-Attainment States in Non-Attainment – Large Regulatory ImplicationsLarge Regulatory Implications

Restrictions on Federal FundingRestrictions on Federal Funding

Costly to manage Costly to manage – $600 million to 1 billion per ppb!!!$600 million to 1 billion per ppb!!!

Why Ozone?Why Ozone?

Limited emission reduction sources leftLimited emission reduction sources left

Why Trees?Why Trees?

TT

RR

EE

EE

Temperature reductionTemperature reduction

RR

EE

EE

Latent Heat of VaporizationLatent Heat of Vaporization

Heat of vaporization for water = 539 cal / g

(Data from Lawrence Berkeley Lab)

Temperature reductionTemperature reduction

RemovalRemoval

EE

EE

Pollution Removal by Trees

0

0.5

1

1.5

2

2.5

3

3.5

0-3 3-6 6-12 12-18 18-24 24-30 30+

Diameter (in.)

CO SO2 NO2 PM O3

Pollutant Deposition (t) Value ($ x 1000)

O3 274 (73-364) 1,850 (492-2,458)

PM10 384 (150-599) 1,729 (675-2,702)

NO2 143 (64-176) 964 (432-1,190)

SO2 145 (70-230) 240 (116-380)

CO 25 24

Total 971 (382-1,394) 4,807 (1,738-6,753)

-estimated range given in parentheses; value based on median externality value of the pollutant ($/t) times deposition value

- 15.7% tree cover

Air Pollution by Trees Air Pollution by Trees in Philadelphia, PA (1994)in Philadelphia, PA (1994)

Temperature reductionTemperature reduction

RemovalRemoval

EmissionsEmissions

EE

Volatile Organic Compounds: VOCsVolatile Organic Compounds: VOCs Natural Plant CompoundsNatural Plant Compounds

- essential oils (odor or essence of species)- essential oils (odor or essence of species)

- toxic to insects and fungal pathogens- toxic to insects and fungal pathogens

- insect aggregation and disaggregation pheromones- insect aggregation and disaggregation pheromones

- plant allelopathy- plant allelopathy

Common TypesCommon Types

- isoprene (light and temperature dependent)- isoprene (light and temperature dependent)

- monoterpenes (temperature dependent)- monoterpenes (temperature dependent)

High Isoprene Emitting GeneraHigh Isoprene Emitting Genera

Casuarina (beefwood) Populus (poplar)

Eucalyptus (eucalyptus) Quercus (oak)

Liquidambar (sweetgum) Robinia (black locust)

Nyssa (black gum) Salix (willow)

Platanus (sycamore)

(>70 ug C / g leaf wt at 30oC and full sunlight)

0

20

40

60

80

100

120

140

160

1 3 5 7 9 11 13 15 17 19 21 23

Hour

VOC

Em

issi

on (k

g)

OVOCs

Monoterpenes

Isoprene

Temperature reductionTemperature reduction

RemovalRemoval

EmissionsEmissions

Energy ConservationEnergy Conservation

TTemperature reductionemperature reduction

RRemovalemoval

EEmissionsmissions

EEnergy Conservationnergy Conservation

Literature - Atlanta Case StudyLiterature - Atlanta Case Study

14% increase in maximum ozone concentration due to loss of vegetation

Maximum: June 4, 1984 123

20% reduction in natural hydrocarbon emissions 116

Photochemical effect (2o C increase) 121

Biogenic emission effect (2o C increase) 137

Anthropogenic emission effect (2o C increase) 140

Ozone conc. (ppb)

(Cardelino and Chameides, 1990)

Los Angeles Basin StudyLos Angeles Basin Study

• Air quality impacts of increased Air quality impacts of increased urban tree cover may be locally urban tree cover may be locally positive or negative with respect to positive or negative with respect to ozoneozone

• Net basin-wide effect of increased Net basin-wide effect of increased urban tree cover is a decrease in urban tree cover is a decrease in ozone concentrations if the ozone concentrations if the additional trees are low VOC emitters additional trees are low VOC emitters

(Taha, 1996)

N

EW

S

Boston

New York CityPhiladelphia

Baltimore

Field Sites

Increase urban tree cover along East Coast from 20 to 40%

Urban Trees and Ozone in the Urban Trees and Ozone in the Northeastern United StatesNortheastern United States

• Increased urban tree cover: Increased urban tree cover: Reduced ozone (OReduced ozone (O33) in urban areas (-1 ppb ) in urban areas (-1 ppb

daytime) daytime)

• Physical effects of trees on pollution removal, air Physical effects of trees on pollution removal, air temperature, wind speed and boundary layer height are temperature, wind speed and boundary layer height are importantimportant

• Tree removal of NOTree removal of NOxx lead to increased O lead to increased O33 at night (loss of at night (loss of

NONOxx scavenging of O scavenging of O33))

• Tree VOC emissions had no detectable (<1 ppb) effect on Tree VOC emissions had no detectable (<1 ppb) effect on OO33(Nowak, Civerolo, Rao, Sistla and Luley, 2000)

Why Trees?Why Trees?

Innovative Strategies GroupInnovative Strategies Group– Interested in use of urban forest Interested in use of urban forest – U.S. EPA, Research Triangle ParkU.S. EPA, Research Triangle Park– 5 meetings since 19935 meetings since 1993

State will have a hard time meeting new air State will have a hard time meeting new air quality standardsquality standards

Trees can reduce ozoneTrees can reduce ozone Innovative approaches needed Innovative approaches needed

Regulatory ApproachRegulatory Approach

State Implementation Plan (SIP)State Implementation Plan (SIP)– Show’s EPA how NAAQS will be reachedShow’s EPA how NAAQS will be reached– Legally binding document Legally binding document – Typically developed for a metro area airshedTypically developed for a metro area airshed– Emissions driven/modelingEmissions driven/modeling– Updated by State periodically and approved by Updated by State periodically and approved by

EPA EPA – Shows effect of action on future ozone Shows effect of action on future ozone

concentrations, but assumes system does not concentrations, but assumes system does not change (no land use change)change (no land use change)

SIPsSIPs SIPs contain a series of requirements that are SIPs contain a series of requirements that are

structured to reduce emissions or prevent additional structured to reduce emissions or prevent additional emissions from occurring that contribute to air emissions from occurring that contribute to air quality problems. The SIPs must include provisions quality problems. The SIPs must include provisions to: to: – monitor the ambient air to determine air qualitymonitor the ambient air to determine air quality– establish rules, regulations, permitting restrictions and establish rules, regulations, permitting restrictions and

other programs to limit emissions from industry, other programs to limit emissions from industry, businesses, cars trucks and busesbusinesses, cars trucks and buses

– establish legal authority, resources, and enforcement establish legal authority, resources, and enforcement sufficient to ensure compliance with the restrictions on sufficient to ensure compliance with the restrictions on emissionsemissions

– model the airshed to: a) estimate the air quality impact of model the airshed to: a) estimate the air quality impact of State and Federal rules, regulations, and other programs; State and Federal rules, regulations, and other programs; and b) demonstrate that the restrictions on emissions will and b) demonstrate that the restrictions on emissions will actually achieve air quality compliance air over time. actually achieve air quality compliance air over time.

SIP ApproachSIP Approach

Place tree cover goals in SIPPlace tree cover goals in SIP– Tie ozone attainment to cover goalsTie ozone attainment to cover goals– State would depend on urban forest State would depend on urban forest

management for attainmentmanagement for attainment

Would require the State to meet forestry Would require the State to meet forestry goals goals

Potential funds for urban forestryPotential funds for urban forestry

Goal of MeetingGoal of Meeting

Facilitate Facilitate discussion and discussion and action on how action on how to use urban to use urban vegetation as a vegetation as a means to means to reduce ozone reduce ozone within SIPswithin SIPs