Manning says that most people don't worry much about the health of plants, but he views the plant world's fragile condition as a symptom of a much larger problem. That's what we need to find out. But, in the meantime, it's important for us to determine how ozone exposure affects our forests, our wetlands, our crops, and even our backyards. There's much science knows about ozone, he says, from studies that began with the 1970 Clean Air Act. At higher levels, plants and animals suffer.
Ozone is the main component of smog, and is blamed for a multitude of serious human health problems.
According to Manning, young children, asthmatics, and the elderly are especially sensitive to high ozone levels in the air. We have fewer days of extremely bad air, thanks to the Clean Air Acts. On bad days, some plants are getting ozone at concentrations of 60-80 parts per billion. The 1970 Clean Air Act and subsequent amendments require the U.S. Environmental Protection Agency to set national health standards, and use those standards to regulate emissions from motor vehicles, electric power plants, and other combustion sources, based solely on scientific evidence. The problem, says Manning, is that there are no biologically based standards of ozone safety set for plants.