Study says tugboats are sootiest for amount of fuel used

They may be relatively small, but tugboats puff out more soot for the amount of fuel used than other commercial vessels, according to a new study.

Scientists from the National Oceanic and Atmospheric Administration and the University of Colorado found that tugboats emit almost a gram of soot per kilogram of fuel burned. Oceangoing tankers and freighters release half a gram of soot per kilogram of fuel burned while at dock and slightly less while moving, according to the study in the journal Geophysical Research Letters.

Tugboats can have a large impact on air quality because they typically operate close to urban areas, pushing ships in and out of harbors and moving barges.

Soot is a black substance formed by combustion that, if inhaled, can cause health problems.

Hampton Roads' two largest tugboat companies operate 29 tugs in the port.

Steps are being taken to reduce tugboats' emissions. In March, the U.S. Environmental Protection Agency announced new air pollution requirements that require diesel-burning tug s and other vessels as well as locomotives to cut soot emissions by 90 percent and smog-causing chemical releases by 80 percent. The regulations will be phased in starting next year, with all ships and locomotives expected to meet the new standards by 2030.

On Wednesday, a tugboat trade group said the vessels are environmentally friendly, as they can push a ton of cargo farther on a gallon of fuel than can a train or a truck.

"Overall, we are the cleanest mode of freight transportation," said Mary McCarthy, a government affairs associate with The American Waterways Operators in Arlington.

Gregory Richards, (757) 446-2599, gregory.richards@pilotonline.com