The U.S. Environmental Protection Agency has awarded $4.2 million in grant funding for clean diesel projects at six U.S. ports.

The announcement was made Wednesday during the EPA’s inaugural Port Stakeholders Summit in Baltimore.

The grants will be used to improve air quality and reduce carbon emissions with money provided through Diesel Emissions Reduction Act to retrofit, replace, or repower diesel engines resulting in immediate emissions reductions in harmful pollution, according to the agency.

The grant recipients are the Port of Seattle, the Port of Hueneme, the Port of Tacoma, the Maryland Port Administration, the Virginia Port Authority and the Port of Los Angeles.

“Ports are the main gateway for U.S. trade and are critical to our country’s economic growth, yet the communities surrounding ports face serious environmental challenges,” said EPA administrator Gina McCarthy. “Today we demonstrate that through collaboration and innovation we can achieve the goals of economic growth and environmental stewardship.”

Most of the country’s busiest ports are located in or near large metropolitan areas and, as a result, people in nearby communities can be exposed to high levels of pollution, said EPA.

“For example, diesel powered port equipment can seriously impact air quality for nearby residents and generate substantial greenhouse gas and black carbon emissions,” the agency said. “Implementing clean air strategies at ports will reduce emissions and provide health benefits from improved air quality for workers and families who live nearby.”