APPENDICES - Laserfiche WebLink

Page 10 In 2024, trees in City of Pleasanton emitted an estimated 12.59 tons of volatile organic compounds (VOCs) (7.016 tons of isoprene and 5.57 tons of monoterpenes). Emissions vary among species based on species characteristics (e.g. some genera such as oaks are high isoprene emitters) and amount of leaf biomass. Fifty- one percent of the urban forest's VOC emissions were from Coastal live oak and California white oak. These VOCs are precursor chemicals to ozone formation.³ General recommendations for improving air quality with trees are given in Appendix VIII. ³ Some economic studies have estimated VOC emission costs. These costs are not included here as there is a tendency to add positive dollar estimates of ozone removal effects with negative dollar values of VOC emission effects to determine whether tree effects are positive or negative in relation to ozone. This combining of dollar values to determine tree effects should not be done, rather estimates of VOC effects on ozone formation (e.g., via photochemical models) should be conducted and directly contrasted with ozone removal by trees (i.e., ozone effects should be directly compared, not dollar estimates). In addition, air temperature reductions by trees have been shown to significantly reduce ozone concentrations (Cardelino and Chameides 1990; Nowak et al 2000), but are not considered in this analysis. Photochemical modeling that integrates tree effects on air temperature, pollution removal, VOC emissions, and emissions from power plants can be used to determine the overall effect of trees on ozone concentrations.