Population: 442,179
Cardiovascular cases: 89,570
Rank in most ozone-polluted cities: 2
Lying just south of Fresno, the skies of this small city bear the brunt of some of the pollution produced by its larger neighbor.
But Visalia can't blame it all on Fresno. Agricultural lands surrounding the town depend heavily on irrigation and many of the pumps bringing water to dry farmlands burn diesel, which produces both particle pollution and ozone.
"Over the past few years, most of those diesel pumps have been switched over to electricity," said Holt of the Valley's Air Quality District.
Air quality has also improved, she said, because the agency has used federal and state grants to pay residents to replace wood-burning stoves and fireplaces with gas or electricity.
NEXT: 5. Fresno, Calif.
