What is EPAs secondary standard for ozone?
Crops and trees appear to be more sensitive to ozone than human health is. The EPA cites studies showing that about one third of the country probably has concentrations of ozone that can result in losses up to 10 per cent of many crops. In some areas, particularly in California, the losses may well run higher than 10 per cent. (154) Going to the proposed primary standard of 0.08 ppm would help substantially. But the crop studies indicate that much of the harm comes not from high daily peaks but from prolonged exposure day after day to relatively low concentrations. It not clear that the 0.08 ppm daily standard would adequately address long-term exposure of plants. (156, 168) The EPA has decided, at this point, to straddle the issue. It is proposing two alternatives. One is to do as it has done with PM, making the primary standard also the secondary standard. The other proposal is more complex. It would establish a new standard based on accumulated exposure for the three months of maxim
