Are you referring to environmental swabbing?
Zone 1 surfaces includes all food contact surfaces and utensils.
Zone 1 surfaces should be a priority in order to reduce the risk of cross contamination.
Conveyor Belts
Rollers
Brushes
Table tops where produce is handled
Workers' hands
Reusable plastic containers and storage bins
Sinks
Knives
Bucket elevators
Zone 2 includes surfaces which are not in direct contact with produce but are in close proximity or adjacent to food contact surfaces in packing areas. Although they were not designed to have contact with food, they can still become a source of contamination. These areas are immediately adjacent to Zone 1, and as such need to be cleaned and sanitized with a sufficient frequency to prevent them from becoming a source of cross contamination. Some examples of Zone 2 areas include:
Outer parts of machines
Framework
Walkways
Sidewalks
Pumps and engines
Chill units
Tools and cart wheels
Machinery control panels
Zone 3 includes Non-Food Contact Surfaces. Surfaces that under normal operating procedures do not contact surfaces of the food or container. These are the areas adjacent to Zone 2 such as floors, trash cans, and storage areas. Other zone 3 areas that can contribute to cross contamination if not properly cleaned include:
Restrooms
Storage areas
Drains
Catwalks
Zone 4 includes Non-Food Contact Surfaces in remote areas beyond the packing area. These are remote areas outside of the packing area that generally do not contribute to direct product contamination. Zone 4 areas include:
Hallways
Restrooms and locker rooms
Cafeteria and break room
Offices
Coolers, freezers, storage rooms
Maintenance shop