The farming communities of the Central Valley breathe some of the worst air in the nation

As we reported earlier this week, the World Health Organization released its latest report measuring air quality in cities all over the world. The report specifically looks at the concentration of particles measuring 10 micrometers or less – those likely to get into the blood stream and cause disease.

Of the 375 U.S. cities included in the list, only 36 of them exceed the WHO’s air quality standard of 20 micrograms of particulates per cubic meter, on average. That’s pretty good. But of the ten worst performing cities, five are located in California’s Central Valley.

So what’s going on here?

The Central Valley of California, anchored by cities like Fresno, Bakersfield, and Modesto, is the farming center of the state, and really the country. Its eight counties grow about half of the nation’s fruits and vegetables. This fact is largely due to its geography – a wide valley that’s also the unfortunate cause underlying much of its persistent problems with air pollution.

Surrounded on three sides by mountain ranges, the Central Valley acts as a pool for pollutants produced by the region’s roughly 3.5 million residents, its industry and its large agricultural community. These emissions get trapped in the valley by an inversion layer of warm air, explains Dimitry Stanich of the California Air Resources Board.

“California has had the worst smog problems in the States for 40 years,” Stanich says.

And the Central Valley is feeling the brunt of it. In addition to the Valley’s unique geographic and meteorological conditions, it’s also a growing population center. Fresno County, the most populous in the region, grew by 16 percent between 2000 and 2010, and now houses more than 930,000 people. More people, and more cars.

“One of the big things we’re dealing with is that we have a 1 to 2 ratio of people to vehicle miles traveled,” says Jaime Holt at the San Joaquin Valley Air Pollution Control District.

These mobile sources of emissions add to the Valley’s problems, but Holt argues they’re not the main cause. The region’s agriculture is responsible for much of the region’s pollution. Up until a few years ago, farmers in the region would regularly burn brush and cuttings at the end of the season, creating huge sources of particulate matter in the air. A new state law, enforced since 2004, regulates the emissions of the agriculture industry in the state, and Holt says the Valley’s pollution problems have already started to decline. In 2002, more than 4,600 tons of 2.5-microgram particulate matter was recorded. In 2008, that figure was down to 1,600 tons.

The problem is getting better, but it’s by no means solved. As agricultural burn-offs continue to decrease, the Valley can expect to see its air quality improve. But regardless of the value of those improvements, its geography and meteorology distinctly disadvantage it to suffer below average air quality.

About the Author

Most Popular

  1. photo: A lone tourist in Barcelona, one of several global cities that have seen a massive crash in Airbnb bookings.
    Coronavirus

    Can Airbnb Survive Coronavirus?

    The short-term rental market is reeling from the coronavirus-driven tourism collapse. Can the industry’s dominant player stage a comeback after lockdowns lift?

  2. Illustration: two roommates share a couch with a Covid-19 virus.
    Coronavirus

    For Roommates Under Coronavirus Lockdown, There Are a Lot of New Rules

    Renters in apartments and houses share more than just germs with their roommates: Life under coronavirus lockdown means negotiating new social rules.

  3. photo: South Korean soldiers attempt to disinfect the sidewalks of Seoul's Gagnam district in response to the spread of COVID-19.
    Coronavirus

    Pandemics Are Also an Urban Planning Problem

    Will COVID-19 change how cities are designed? Michele Acuto of the Connected Cities Lab talks about density, urbanization and pandemic preparation.  

  4. Equity

    The Problem With a Coronavirus Rent Strike

    Because of coronavirus, millions of tenants won’t be able to write rent checks. But calls for a rent holiday often ignore the longer-term economic effects.

  5. A pedestrian wearing a protective face mask walks past a boarded up building in San Francisco, California, U.S., on Tuesday, March 24, 2020. Governors from coast to coast Friday told Americans not to leave home except for dire circumstances and ordered nonessential business to shut their doors.
    Equity

    The Geography of Coronavirus

    What do we know so far about the types of places that are more susceptible to the spread of Covid-19? In the U.S., density is just the beginning of the story.

×