Some of the world's most popular cruise lines are in hot water with the Environmental Protection Agency (EPA).
Holland America Line-Westours Inc., Princess Cruises, Celebrity Cruises, Norwegian Cruise Line, Carnival Cruise Line and World Explorer Cruises were cited Tuesday.
According to EPA, 13 of the companies' ships violated air pollution regulations.
As a result, the companies could be fined up to $27,500 per incident and could be ordered to install pollution control equipment or take other action.
Spokesmen for Holland America and Princess Cruises said the companies will review their emissions records.
The companies have 30 days to respond to EPA notices.
The citations are the latest in a crackdown on cruise ship pollution in Alaska.
Last year, a federal judge in Anchorage fined Royal Caribbean $6.5 million for illegally dumping waste oil and other pollutants.
EPA's investigation marked the first time the agency has gone after the cruise ship industry for air pollution violations in Alaska.
The investigation was prompted by complaints from the public and because the Alaska Department of Environmental Conservation stopped monitoring cruise ship emissions in 1996, citing budget cuts, EPA investigator John Pavitt said.