BOULDER, Colo. — New research from Energy Futures finds that ports for container ships are among the biggest sources of pollution and greenhouse gas emissions in the United States, and that recent efforts to curb pollution are not yet making a noticeable difference.

The report, "U.S. Container Ports and Air Pollution: a Perfect Storm," studied the pollution control efforts for 10 months in 2007 at the country's 10 busiest container ports, which together handle as much as 80 percent of all U.S. imports.

James Cannon, the president of Energy Futures and the author of the report, said that a combination of factors made ports especially hazardous to human health, in addition to their impacts on air and water quality.

The "perfect storm" of the report's title is a result of three main factors: most ports are located in densely populated coastal settings, diesel is the main fuel source for both container ships and the trucks onto which they offload, and the prevailing winds blow onshore. All combined, areas around ports are often substantially more polluted than further outlying areas, and shipping ports generate a significant amount of greenhouse gas emissions.

Of the ports included in the study -- Los Angeles, Long Beach and Oakland in California; New York / New Jersey; Seattle and Tacoma, Wash.; Savannah, Ga.; Hampton Roads, Va.; Charleston, S.C.; and Houston -- the California ports were singled out for their recent efforts to reduce pollution, including powering down ships while at the docks and mandating newer, less polluting big rigs at the ports.

The report examines the growth of shipping and the resulting rise in pollution, and offers policymakers a series of proposals to reduce the health and environmental impacts of these shipping ports. Among the proposals are an increase in the use of alternative fuels and pollution- and emission-reduction technologies; the creation of a federal strategy to clean up ports, coupled with federal-level funding to finance such a program; the development of global standards for ports' environmental conditions; and creating a global clearing house of information and resources for port clean-up efforts.

The full report is available for download from Energy-Futures.com.