Three international shipping firms were fined by the California Air Resources Board after failing to shift from dirty “bunker” fuel to cleaner burning fuel when they entered into state waters.

Oslo-based Hoegh Autoliners Shipping AS Co., NCN Corp. Panama and Singapore-based Twin Phoenix Shipping S.A. received a total of $440,250 in fines after the board investigated their visits to the ports of Long Beach, Los Angeles and Stockton.

Adopted in 2008, the board’s Vessel Regulation curbs 15 tons of diesel particulate matter a day from ship exhaust.

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