"Fertilizer Is Fouling The Air in California: Study"
"Due to heavy fertilizer use, California's Central Valley is behind up to 41 percent of the state's emissions of nitrogen oxide — an air pollutant and climate-warming gas".
"A large proportion of California's nitrogen oxide—which can cause harmful ozone and a variety of health impacts—comes from heavy fertilizer use in the state's Central Valley, according to a new study.