Two former importers of vehicles and engines from China have agreed to pay fines for violating the Clean Air Act, U.S. officials said Wednesday.

The U.S. Environmental Protection Agency and the U.S. Justice Department announced a settlement with Yuan Cheng International Group Inc. and NST Inc., located in Montclair, Calif., which allegedly imported and sold vehicles and engines from China in violation of the act's requirements on emission levels.

The settlement resolves allegations that between 2006 and 2011 the companies imported and sold 17,521 recreational vehicles, highway motorcycles and non-road spark ignition engines without proper EPA certifications.

John Cheng and Jenny Yu, senior company executives, have agreed to pay a combined civil penalty of $50,000, the EPA said.

Both companies are no longer in business.

"When companies or their executives fail to comply with U.S. standards when importing vehicles and engines into the United States, it affects the nation's air quality, impacts consumers and puts businesses that play by the rules at a disadvantage," said Cynthia Giles, assistant administrator for EPA's Office of Enforcement and Compliance Assurance.