By law, kitchen exhaust cleaning is required for basically every commercial cooking location in the United States. Restaurants, hospitals, hotels, employee cafeterias and other nourishment service areas have a hood and ductwork over the stove to exhaust smoke, steam, and fumes out of the building.
These exhaust gases leave a buildup within the ductwork. Overwhelming grease buildup, regardless of whether in an eatery or home, makes a flame danger.