This proposal builds on an earlier feasibility study which successfully developed a model system for exposing plants to realistic measures of urban pollutants. The present study will evaluate the impacts of urban pollution climates on a broad range of plant species (trees, shrubs, herbs & lichens) and insect herbivores, using this facility and a range of supporting roadside transects. Direct impacts of pollutants on growth, physiology and leaf-surface characteristics of plants and plant-herbivore interactions will be assessed. Selective filtration studies will be used to separate effects of different components of exhaust pollution (gases/particles). The influence of abiotic stresses of urban environments (turbulence, water deficit, night illumination) on pollutant uptake, plant growth and plant herbivore interactions will be evaluated.