Large spark-ignited engines used in Nissan Forklift's internal combustion forklifts have been certified by US regulatory bodies as meeting 2007 US environmental regulations.

The US Environmental Protection Agency and the California Air Resources Board have approved Nissan's K21 and K25, and TB45 gasoline, LPG, and dual fuel industrial engines engines. Nissan Forklift had redesigned the engines to include technological features to reduce exhaust emissions.