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Why Does California's Central Valley Have Such Bad Air Pollution?

The farming communities of the Central Valley breathe some of the worst air in the nation
relates to Why Does California's Central Valley Have Such Bad Air Pollution?
Paulo Whitaker / Reuters

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.