The US Environmental Protection Agency (EPA) is granting $1 million (£0.6m) for tribal applicants to replace diesel engines.
The project aims to cut air pollutants from diesel exhausts which are linked to respiratory problems.
The EPA will award up to five tribal grants between $30,000 (£19,300) and $800,000 (£515,000) each.
Projects may include school buses, transit buses, heavy-duty diesel trucks, marine engines, locomotives, energy production generators and other diesel engines.
Chris Grundlerm, Director of EPA’s Office of Transportation and Air Quality said: “The EPA is committed to improving air quality on tribal lands.
“These grants will upgrade and replace diesel engines, resulting in lower exposure to air pollution for tribal citizens and healthier communities.”