The vent hood is a large venting system in a restaurant that allows steam, smoke and pollutants to exit the kitchen. When grease and oil builds up on this system it can become a fire hazard, so restaurant hoods need to be cleaned regularly.
The National Fire Protection Association and all insurance companies, health inspectors, and federal, state and local laws require that all restaurant vent hoods be inspected regularly. How often they should be inspected depends on what kind of food is prepared, how much is prepared, and how it is prepared. All restaurants will need to be inspected at least twice a year.
There are no certification requirements for vent-hood cleaning, but it is best to use professionals who are familiar with the chemicals and special tools needed.
Don't assume that if the company is certified that they will provide quality work. It is best to use companies that provide before-and-after photos of their work.
Ensure that the entire system is cleaned. This includes the fan top and bottom, grease box, ducts, any access panels and the hood itself. If any part of the system is visible, then grease can reach it and needs to be cleaned.
Also, make sure a certificate of completion is provided by the company doing the work. That certifies the date the system was cleaned.