Funding worth up to $5 million (£3m) has been made available for clean diesel projects aimed at reducing emissions from marine and inland water ports.
Older diesel engines emit large amounts of air pollutants such a nitrogen oxides, the US Environmental Protection Agency (EPA) said.
Port authorities, state and local governments can apply for up to $2 million (£1.6m) in funding for projects including engine upgrades, exhaust controls and vehicle replacement. Funding is limited to projects at ports located in areas of poor air quality, the EPA added.
Janet McCabe, Acting Assistant Administrator for the Office of Air and Radiation said: “Communities surrounding ports often face serious air quality and other environmental challenges.
“By working with fleet owners to replace or update older equipment with cleaner technologies, we can find collaborative solutions that foster both economic growth and improve public health.”