Pep Boys agreed to a $5 million settlement with the Environmental Protection Agency (EPA) Monday over alleged Clean Air Act violations.

The car repair chain imported at least 241,000 vehicles and generators manufactured in China that did not meet U.S. environmental standards between 2004 and 2009, according to the complaint. Pep Boys supplier Baja Inc. is also settling with the EPA. When combined, these become the largest vehicle importation settlement ever brought under the Clean Air Act.

“Importers of foreign made vehicles and engines must comply with the same Clean Air Act requirements that apply to those selling domestic products, and this settlement demonstrates that we will take strong action to ensure that importers comply with their obligations,” said Ignacia S. Moreno, assistant attorney general for the EPA’s environment and natural resources division, in a statement.

In addition to the civil penalty, Pep Boys and Baja will be required to pursue measures that offset the emissions produced by imported products already sold to consumers. Pep Boys will, for example, provide discounted push mowers to consumers who wish to trade in gas-powered mowers.