Matthew Thomas, supervisor of the traffic enforcement unit at the sheriff's office of Pinal County, which contains the highest-speed stretch of Route 79.

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Border Patrol officers originally spotted the white Ford Excursion around 4:30 a.m. off the side of Interstate 8 in western Pinal County, about 60 miles south of Phoenix.

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But one of the biggest reasons for Phoenix's high pollution levels is actually cattle ranches found south of the city, in Pinal County and vicinity.. "Those cattle ranches are contributing a lot of fine particle pollution to the small communities near them that are part of the Phoenix metro area, but also to the tribe adjacent to it, " says Nolen.

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