California loses up to $1 billion in crops each year because of air pollution, according to new research that looked at trends from 1980 to 2015. Table grapes — the kind for snacking — were the most vulnerable among seven crops badly affected by smog, including: wine grapes, strawberries, walnuts, peaches, nectarines, and hay. The crops lost between 2 to 22 percent of their yields as a result of smog.

The results show that dirty air comes at a significant economic cost to California, which raked in $50 billion for its agriculture in 2018. Grapes, the hardest hit by pollution, bring in the most money for the state after dairy.

Every American’s diet could be affected

Every American’s diet could be affected since California produces the most agriculture in the US and supplies two-thirds of the country’s fruit and nuts. Some are still losing up to 15 percent of their yields today, the researchers from the University of California at Irvine found in their paper published today in Nature Food.

There is some good news — the state’s efforts to limit pollution over the years did seem to boost the perennial crops — indicating that future efforts to limit pollution can make a difference.

“This is not the main source of calories for anyone but it is kind of the sweet things in life — the fruits and nuts and grapes for wine,” says Steven Davis, one of the authors of the study.

Smog, or ground-level ozone pollution, creeps into the pores of the plants and essentially burns the cells that are trying to photosynthesize, Davis explained to The Verge. This type of pollution wreaks more havoc on plants than all other types of air pollutants combined, according to the US Department of Agriculture. It’s created when emissions from tailpipes and factories go through a chemical reaction under sunlight. California has some of the worst smog in the nation and is home to 10 of the 25 most polluted cities in the US, according to the American Lung Association’s annual report.

To find correlations between smog and crop yields, Davis and his colleagues compared data on ozone concentrations where crops were grown against data on how many pounds of crops were produced each year. Separately, they looked for how rising temperatures affected agriculture and found that pollution had a greater effect.

action on climate change will benefit crops

The scientists predict, however, that taking action on climate change will benefit crops — since curbing pollution from tailpipes cuts down both greenhouse gases and air pollution. Plus, higher temperatures speed up the chemical reactions that create smog.

Davis hopes his work will convince people along California’s agricultural belt that environmental policies will be good for their pocket books. “If you drive through the Central Valley on [Interstate-5] you see lots of signs about relaxing environmental restrictions and letting more water go to agriculture, for example,” Davis says. “At least we’re putting some real numbers on the benefits that some environmental policies may have had for these farmers.”