Mack Trucks Inc. has received certification from the Environmental Protection Agency (EPA) that nine of its heavy-duty on-highway engines meet the requirements for sale after Oct. 1. Mack applied for certification in early March. With the approvals, Mack becomes the first diesel engine maker to have all of its heavy-duty models certified by EPA. Cummins received in April the first EPA certification for its ISX model. To meet EPA post-Oct. 1 standards, engines must emit no more than 2.5 grams of nitrogen oxides. Bob Martin, communications manager for Mack, said the Mack on-highway engines use cooled exhaust gas recirculation technology, as does the approved Cummins engine. Caterpillar Inc., which has stated it cannot meet the EPA deadline, is pursuing a different technol-ogy.