How Air Pollution Affects Olive Oil Quality in California

The ongo­ing impact of cli­mate change has left much of the west­ern United States with air qual­ity prob­lems. According to a recent PBS report, the prob­lem is rooted in California’s San Joaquin Valley.

The south­ern half of California’s Central Valley is the heart of agri­cul­tural pro­duc­tion and dis­tri­b­u­tion. For the last 25 years, the region has been out of com­pli­ance with Environmental Protection Agency stan­dards.

According to a report from KCRA, an NBC tele­vi­sion affil­i­ate in Sacramento, most Californians expe­ri­ence unhealthy lev­els of air pol­lu­tion. The 2023 State of the Air Report con­firmed that many California coun­ties receive fail­ing grades for smoke and ozone pol­lu­tion.

Air qual­ity improve­ments are under­way, such as trans­porta­tion ini­tia­tives, zero car­bon truck­ing, reduc­tion of agri­cul­tural burn­ing and find­ing ways to limit the risk of large wild­fires.

“The good news is we’ve seen some improve­ments in a lot of places across the val­ley,” Congressman Josh Harder, who rep­re­sents com­mu­ni­ties in the San Joaquin Valley, told KCRA. ​“The bad news is we still have a lot of work left to go.”

Harder empha­sized in the report that it is essen­tial to focus on pre­ven­tion, hire more fire­fight­ers and seek to pro­tect the health of future gen­er­a­tions by improv­ing air qual­ity – short and long-term.

Air pol­lu­tion is com­pounded in California by smoke from wild­fires. The California Department of Forestry and Fire Protection reported 5,474 wild­fires burn­ing 104,169 hectares in 2023.

Similar dam­age was reported in 2022. Contrast this with 2020, when more than 8,600 wild­fires con­sumed 1.7 mil­lion hectares and killed 33 peo­ple.

According to CalMatters, a non-profit news orga­ni­za­tion, California wild­fires emit as much car­bon as almost 2 mil­lion cars. In an increas­ingly vicious cycle, cli­mate change wors­ens fire, and fires worsen cli­mate change.

CalMatters reported that in 2020, the state’s wild­fires increased emis­sions by about 30 per­cent. Scientists from the University of California – Los Angeles describe the state’s efforts to achieve cli­mate goals as going ​“up in smoke.”

According to a Baker Wine & Grape Analysis newslet­ter, there have been ques­tions in recent years about smoke taint in olives and olive oil. ​“Thankfully, it seems as though olives fare much bet­ter than grapes in the pres­ence of wild­fire smoke,” the lab reported.

The newslet­ter cited Selina Wang, an asso­ciate pro­fes­sor at the University of California-Davis’ food sci­ence and tech­nol­ogy depart­ment, say­ing that olives are less sus­cep­ti­ble than wine­grapes to smoke taint thanks to thicker olive skins.

“All crops, includ­ing olives, are vul­ner­a­ble to smoke taint, depend­ing on its matu­rity index and ripen­ing stage, the dis­tance between the orchard and active fire, how long the expo­sure to smoke con­tin­ued before har­vest, how close the fire to the har­vest period and rain event,” Wang told Olive Oil Times.

“I am not aware of sig­nif­i­cant recent wild­fire effects on olive grow­ing and pro­duc­tion,” she added.

The pro­tec­tive cutic­u­lar wax, the fact that ash is insol­u­ble in oil, and the wash­ing step in the milling min­i­mize the oppor­tu­nity for smoke to taint olives and olive oil.

“Most research on smoke taint has been done on wine grapes,” Wang said. ​“Olives are thicker and have more waxy skins than grapes, so olives have nat­ural pro­tec­tions against smoke taint.”

“From an air qual­ity stand­point, olive trees and olive farm­ing cre­ate far less air pol­lu­tion than farm­ing the annual crops that are replanted and tilled up every year to go into refined seed oils,” Samantha Dorsey, pres­i­dent of McEvoy Ranch, told Olive Oil Times. ​“Because olive trees are per­ma­nent crops, they are sig­nif­i­cant car­bon sinks as well.”

Dorsey described McEvoy Ranch’s expe­ri­ence dur­ing times of poor air qual­ity.

“With many years of wild­fire smoke pol­lu­tion in California, we have had lots of oppor­tu­nity to study our olives that have sat in smoke for weeks on end,” she said. ​“We have found zero traces of smoke taint or the smoke taint marker, guia­col, in any of our olives or extra vir­gin olive oil.”

“Olive oil is unique in that it does not absorb any of its aro­matic or fla­vor com­pounds until it is milled, which leaves the oil inside the olive on the tree quite pro­tected against wild­fire smoke,“ Dorsey added.

Looking at the big­ger pic­ture of envi­ron­men­tal impact, olive oil is supe­rior to other edi­ble oils.

“From a long-term sus­tain­abil­ity stand­point (vis a vis air qual­ity and many other envi­ron­men­tal mark­ers), olive oil is supe­rior to any other edi­ble oil on the mar­ket,” Dorsey said.

“Its pro­duc­tion inputs are com­par­a­tively low, the trees them­selves sequester car­bon at a fan­tas­tic rate, it is a per­ma­nent crop that does not require replant­ing each year (unlike seed oils), it is shelf sta­ble (unlike dairy), you can extract the oil phys­i­cally instead of chem­i­cally, and it is incred­i­bly healthy,” she added.

• PBS
• KCRA