I think the question was what country has the toughest emission
standards.
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Emission testing is only in the densely populated areas of Utah,
according to DMV. That includes areas such as Salt Lake and Davis
counties. Washington County has a safety inspection, but not
emission testing.
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Alabama
Arkansas
Alaska
Florida
Hawaii
Iowa
Kansas
Kentucky
Maine
Michigan
Minnisota
Mississippi
North Dakota
Oklahoma
West Virginia
None of these states have emissions testing.
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United states
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Foreign car manufacturers will have to meet those emission standards on cars they export to the U.S.