The salt breeze on the deck of a cruise ship may not be as fresh and clean as the beach air its meant to evoke, a new study reveals.
An associate professor at the Johns Hopkins Bloomberg School of Public Health, Ryan Kennedy, secretly measured the amount of ultrafine particles in the air on four cruise ships. He found measurements similar to prominently polluted places such as Beijing and Taipei, Taiwan, with the worst readings taken in areas designated for exercise or children's activities.
Carnival Corporation said Kennedy's tests were "completely ridiculous, inaccurate and in no way represent reality".
Kennedy's research contradicts the long-held belief that the air at sea is clean, and that the emissions from cruise ships don't affect passengers.
"I think there's a perception that these ships are out there in the middle of nowhere and the winds just disperse it," Kennedy said. "You're still being exposed to these ultrafine particles."
Kennedy tested the air on four cruise ships: Carnival Liberty in October 2017, Carnival Freedom in April-May 2018 in the Caribbean, Holland America Amsterdam in October 2018, and Princess Emerald in November 2018 off the west coast of the United States.
He counted the tiny particles of pollutants in the air on board, called ultrafine or nano particles because each piece is smaller than 0.1 cubic centimeters. Currently, the Environmental Protection Agency doesn't have standards for safe limits of those particles, although an EPA scientific advisory board met last month to begin reviewing data.
Naresh Kumar, an associate professor of environmental health in the University of Miami's department of public health sciences, said the elevated levels found on the ships' decks "should be a matter of concern" given how easily those tiny particles can infiltrate the body.
In this study, Kennedy secretly counted pollutants at port and at sea. He found average particle counts ranging from 1,540 to 33,514 particles per cubic centimeter across all four ships. Before the study began, he tested the air on a beach and found an average reading of under 500 particles per cubic centimeter. A nearby idling diesel car registered in the tens of thousands.
He compared these results to tests done with the exact same device in infamously polluted cities. A busy street in Beijing in 2009 showed concentrations of about 30,000 particles per cubic centimeter, and a train station in Taipei in 2009 had readings averaging 15,500 particles per cubic centimeter.