The detrimental effects of ambient ozone on crops, even at relatively low concentrations, are well-established (Thompson et al., 1976; Heck and Brandt, 1977; Heck et al., 1982; Environmental Protection Agency, 1984; California Air Resources Board, 1987; Olszyk et al., 1988a, 1988b; Heagle et al., 1986; McCool et al., 1986,...

Particles and gases in the atmosphere scatter and absorb light, and thereby reduce visibility (Watson and Chow, 1994; Richards et al., 1990; Ozkaynak et al., 1985). Although natural sources of particles, such as volcanoes, can significantly degrade visibility, it generally is true that “when...