Urban Tree Cover: An Innovative Strategy for Air Quality Planning

1. Urban Tree Cover: An Innovative Strategy for Air Quality Planning David J. Nowak USDA Forest Service Northeastern Research Station Syracuse, NY

2. Goal • Use urban tree cover and its management as a strategy to reduce ozone with State Implementation Plans

3. Overview • History – How we got here • Why Ozone? • Why Trees? • SIPs – brief overview

4. History – How we got here • 1992 NUCFAC grant • Feasibility of funding urban tree management based on the benefits of urban trees

5. 1992 NUCFAC Grant • Can we convert benefits to dollars? • CO2 and Carbon • Global warming • Air pollutants • Commodity trading of NOx and SOx

6. Final Result • Ozone reduction by trees had the greatest funding potential • EPA seemed interested • Regulatory programs termed “directionally sound”

7. 1995 NUCFAC Grant • Quantify the effect of urban trees on ozone • Urban forest field survey • NYC, Philadelphia, Baltimore, Boston • Cover and composition study • Used and improved “EPA” models • Updated cover data, VOC emissions data, deposition data • NYS DEC Division of Air Resources • Modeling work

8. U.S. East Coast Study-1995 • Increased tree cover from 20% to 40% in urban cells • Demonstrated a measurable impact on ozone (Nowak, Civerolo, Rao, Sistla, Luley and Crane, 2000)

9. 1995 NUCFAC Grant • Met with EPA • Presented the East Coast study (w/ NYS DEC) • EPA appreciative of research but: • Needed data specific to one non-attainment area (NYC)

11. What Happened? • NYS has decided to wait to submit a request to the EPA – Jan 2002 • No reason to submit at that point • Already accepted • Next SIP call

12. Latest Meetings • Summer 2002: Met with EPA Administrator Christine Todd Whitman to discuss urban tree issues • Mike D’Errico • Roni Olizo • Feb. 2003: Met with EPA Staff • Maryland came on board (work also on-going in Houston) • Defined and discussed a series of regulatory issues • Developed paper on issues • April 2004: Meeting with State Foresters and Air Quality personnel

13. Ozone VOC’s and NOx are precursors Highest under high temperatures during the day No point source So control strategy is typically aimed at VOC and NOx emission reductions

14. Why Ozone? • Significant effects on human health, plants and environmental quality:

15. Why Ozone? • Persistent problem • Many areas still in non-attainment • 159 million people affected • 474 counties or parts of county in non-attainment

16. Non Attainment – EPA Region 1 [1]Includes Tribal lands 1Includes Tribal lands

17. Non Attainment – EPA Region 2 [1]Includes Tribal lands 1Includes Tribal lands 1Includes Tribal lands 2EPA decision on attainment or nonattainment designation by the end of 2004 pending review of data

18. Non Attainment – EPA Region 3

19. [1]Includes Tribal lands 1Includes Tribal lands

20. Why Ozone? • States in Non-Attainment • Large Regulatory Implications • Restrictions on Federal Funding • Costly to manage • $600 million to 1 billion per ppb!!!

21. Why Ozone? • Limited emission reduction sources left

22. T R E E Why Trees?

23. Temperature reduction R E E

24. Latent Heat of Vaporization Heat of vaporization for water = 539 cal / g

25. (Data from Lawrence Berkeley Lab)

26. Temperature reduction Removal E E

28. Air Pollution by Trees in Philadelphia, PA (1994) • estimated range given in parentheses; value based on median externality value of the pollutant ($/t) times deposition value • 15.7% tree cover

29. Temperature reduction Removal Emissions E

30. Volatile Organic Compounds: VOCs • Natural Plant Compounds - essential oils (odor or essence of species) - toxic to insects and fungal pathogens - insect aggregation and disaggregation pheromones - plant allelopathy • Common Types - isoprene (light and temperature dependent) - monoterpenes (temperature dependent)

31. High Isoprene Emitting Genera (>70 ug C / g leaf wt at 30oC and full sunlight) Casuarina (beefwood) Populus (poplar) Eucalyptus (eucalyptus) Quercus (oak) Liquidambar (sweetgum) Robinia (black locust) Nyssa (black gum) Salix (willow) Platanus (sycamore)

33. Temperature reduction Removal Emissions Energy Conservation

34. Temperature reduction Removal Emissions Energy Conservation

35. Literature - Atlanta Case Study Ozone conc. (ppb) Maximum: June 4, 1984123 20% reduction in natural hydrocarbon emissions116 Photochemical effect (2o C increase)121 Biogenic emission effect (2o C increase)137 Anthropogenic emission effect (2o C increase)140 14% increase in maximum ozone concentration due to loss of vegetation (Cardelino and Chameides, 1990)

36. Los Angeles Basin Study • Air quality impacts of increased urban tree cover may be locally positive or negative with respect to ozone • Net basin-wide effect of increased urban tree cover is a decrease in ozone concentrations if the additional trees are low VOC emitters (Taha, 1996)

37. Field Sites Boston Philadelphia New York City Baltimore N W E Increase urban tree cover along East Coast from 20 to 40% S

41. Urban Trees and Ozone in the Northeastern United States • Increased urban tree cover: Reduced ozone (O3) in urban areas (-1 ppb daytime) • Physical effects of trees on pollution removal, air temperature, wind speed and boundary layer height are important • Tree removal of NOx lead to increased O3 at night (loss of NOx scavenging of O3) • Tree VOC emissions had no detectable (<1 ppb) effect on O3 (Nowak, Civerolo, Rao, Sistla and Luley, 2000)

43. Why Trees? • Innovative Strategies Group • Interested in use of urban forest • U.S. EPA, Research Triangle Park • 5 meetings since 1993 • State will have a hard time meeting new air quality standards • Trees can reduce ozone • Innovative approaches needed

44. Regulatory Approach • State Implementation Plan (SIP) • Show’s EPA how NAAQS will be reached • Legally binding document • Typically developed for a metro area airshed • Emissions driven/modeling • Updated by State periodically and approved by EPA • Shows effect of action on future ozone concentrations, but assumes system does not change (no land use change)

45. SIPs • SIPs contain a series of requirements that are structured to reduce emissions or prevent additional emissions from occurring that contribute to air quality problems. The SIPs must include provisions to: • monitor the ambient air to determine air quality • establish rules, regulations, permitting restrictions and other programs to limit emissions from industry, businesses, cars trucks and buses • establish legal authority, resources, and enforcement sufficient to ensure compliance with the restrictions on emissions • model the airshed to: a) estimate the air quality impact of State and Federal rules, regulations, and other programs; and b) demonstrate that the restrictions on emissions will actually achieve air quality compliance air over time.

46. SIP Approach • Place tree cover goals in SIP • Tie ozone attainment to cover goals • State would depend on urban forest management for attainment • Would require the State to meet forestry goals • Potential funds for urban forestry

47. Goal of Meeting • Facilitate discussion and action on how to use urban vegetation as a means to reduce ozone within SIPs