The San Joaquin Valley is the land of Big Agriculture. Stretching 250 miles from Bakersfield in the south to Stockton in the north, the San Joaquin comprises the southern two-thirds of the storied Central Valley, a plowed-over promised land covering seven million acres of irrigated fields that generate more than $17 billion a year in crops — with the vast majority coming from three San Joaquin Valley counties. In sum, the region supplies a quarter of the food on American plates.
It is also awash in air pollution. Millions of beef and dairy cattle, millions of acres of dusty crops, and the truck traffic to support these mega-operations generate fine airborne particles that linger and swirl in what is, in effect, a gigantic, pollution-trapping bowl bounded by mountains. Add in prolific use of wood stoves and barbecue pits, the second-hand smog blowing into the valley from cities to the west and the north, and emissions from some of the densest oil fields in the lower 48 states, and the result is some of the worst air pollution in the nation.