FLAG - OZONE FLAG Ozone Subgroup Bob Musselman, Subgroup Leader – FS-R Miguel Flores – NPS Tonnie Maniero – NPS Rich Fisher – FS-WO Suraj Ahuja – FS-R5 Janice Peterson – FS-R6 Trent Procter – FS-R5 Bill Jackson – FS-R8 Jim Renfro – NPS Judy Rocchio – NPS Andrzej Bytnerowicz – FS-R
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Agricultural cropsNative plants
Yield, Productivity Growth
Leaf necrosis Leaf necrosis
Quality Ecosystems form,
Agricultural cropsNative plants
Small variability Large variability
Nutrition, primarily nitrogen
Moisture: relative humidity and soil moisture
Solar radiation, temperature
Regional climatic differences
Age of plant, phenological state of development
Injury: All physical or biological responses to pollutants, such as changes in metabolism, reduced photosynthesis, leaf necrosis, premature leaf drop, and chlorosis.
Damage: Reduction in the intended use or value of the biological or physical resource; for example, economic production, ecological structure and function, aesthetic value, and biological or genetic diversity that may be altered through the impact of pollutants.
Exposure – ozone present in ambient air
Dose – ozone taken up into plant tissue
Flux – the rate at which plant surfaces absorb ozone
Effective flux – flux minus defensive response
Defenses –passive and active
AOT40 in Europe; 50 W/m2
SUM06, recommended by EPA
8 am – 7:59 pm
Some European, U.S. Scientists
May, June, July (AOT40 - crops)
June, July, August (U.S.)
Running 3-month (AOT40)
April through September (AOT40 - forests)
April through October (U.S.)
FLAG RECOMMENDATIONS FOR EVALUATING OZONE IMPACTSFLAG has selected the W126 metric as most appropriate to describe ozone exposure for vegetation. The metric is based on a 24-hour, seasonal (April through October) period of measurement. FLAG also recognizes the importance of considering the number of hours in this period of time greater than or equal to 100 ppb (N100) given the importance of peak concentrations in plant response.
for selected species.
Table mountain pine 20.0 2
Sweetgum 5.6 3
Sycamore 31.2 89
Winged sumac 3.3 5
Black cherry 11.5 10
Tall milkweed 0.3 0
Black-eyed susan 12.8 50
Dwarf dandelion 0.3 0
Yellow buckeye 4.7 3
Virginia pine 30.0 50
Cutleaf coneflower 5.5 3
W126 (ppm-hrs) and N100 values for 10% growth loss for selected species.
Aspen 259 6.4 4
Aspen wild 71.4 243
Black Cherry 6.5 1
Red Maple 85.4 245
Whorled-wood aster 8.2 10
Yellow poplar 14.4 4
Eastern white pine 30.2 66
Sugar maple 44.7 131
Sycamore 15.4 27
Winged sumac 9.7 4
FLAG RECOMMENDATIONS FOR EVALUATING OZONE IMPACTSNOx and VOC emissions are of concern because they are precursors of ozone. Current information indicates most FLM areas are NOx-limited most or all of the time. Until we determine such is not the case, we will focus on control of NOx emissions.
FLAG RECOMMENDATIONS FOR EVALUATING OZONE IMPACTSFLAG agrees with EPA and others that single source-receptor modeling for ozone is not feasible at this time. FLM actions or specific requests on a permit application will, therefore, be based on the existing air pollution situation at the FLM area(s) that may be affected by the source. FLM response will depend on (1) whether or not ozone phytotoxic effects have been documented in the area, and (2) whether or not ozone exposure levels occurring in the area have been shown to be phytotoxic.
a. The FLM may recommend one or more of the following: - That the proposed source use stricter (than BACT) controls (e.g., Lowest Achievable Emission Rate [LAER]) - That the proposed source obtain NOx emission offsets that will benefit the potentially affected FLM area (as demonstrated by dispersion modeling). - That the permitting authority (i.e.state or EPA) conduct regional modeling to identify sources that are contributing significantly to ozone-associated impacts in the FLM area, and that the permitting authority then undertake actions necessary to reduce emissions from those sources (e.g., SIP revision).b. That the applicant calculate the ozone exposure for vegetation (using the W126 and N100 metrics) for the affected FLM area(s) where such information is not already available.c. That the permitting authority or applicant fund post-construction ambient ozone monitoring in or near the FLM area.d. That the applicant conduct or fund post-construction ozone effects monitoring/research in the FLM area.
U.S. EPA ozone information:
NPS ozone information:
Ozone effects research, USDA ARS, North Carolina:
Ozone effects research, England:
Ozone effects research, Switzerland:
Ozone exposure metrics for vegetation: