To limit the probability that cooking vapours or residue will accumulate and subsequently be ignited, which could lead to a fire or explosion, which could lead to:
To limit the probability that commercial cooking equipment exhaust will ignite nearby combustible material, which could lead to a fire, which could lead to harm to persons.
To limit the probability that fire protection systems for commercial cooking equipment exhaust will not properly operate in a fire situation, which could lead to the spread of fire to other parts of the building, which could lead to harm to persons.