Recent evidence has confirmed that air pollution, principally in the form of the photochemical oxidant ozone (03)' has significantly reduced yields of major agronomic crops throughout the U.S. Estimates of economic losses to agriculture induced by 03 have varied widely, but the most reliable estimate of total aggregate damage is on the order of $3 billion (Adams et al., 1984). California, with the largest and most diverse agricultural economy of any state and also, unfortunately, with the most severe photochemical oxidant problem, is particularly susceptible to 03-induced crop losses. Estimates of the economic impacts of air pollution on agriculture in California have varied widely (Adams et al., 1982; Howitt et al., 1984, 1985; Leung et al., 1982; Rowe and Chestnut, 1985). Loss estimates for the state have ranged from $37 million (Howitt et al.,1985) to $300 million (Leung et al., 1982). The California Air Resources Board (CARB) has estimated benefits to agriculture from cleaner air ranging from $330 million to $50 million, depending upon attainment of specific 03 standards (CARB, 1987). The rationale for the CARB assessment, including the specific 03 dose-crop yield loss equations upon which it is based, has recently been described by Olszyk et al. (1988).
Some of the uncertainty in estimates of economic losses from 03 stems from uncertainties in the biological data base of 03 dose-crop loss equations. The cultivar or cultivars selected for study in a dose-response experiment are normally chosen on the basis of their economic importance or ease of growth at a particular experimental site, and not on how accurately they reflect the range of 03 responses expected in the crop species as a whole. Thus one of the major uncertainties in crop loss assessments is the degree to which cultivars differ in their responses to 03 and the degree to which the crop loss assessment model is sensitive to these differences. Most dose-response experiments have been conducted on only one or two cultivars of the most widely grown crop plants. Plant cultivars vary widely in response to 03 (NAS, 1976), so dose-response equations generated for a single cultivar may not adequately represent the response of the species as a whole.
For questions regarding this research project, including available data and progress status, contact: Research Division staff at (916) 445-0753
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