A food handler is assigned to monitor self-service food bars because customers may:

Self-service areas, such as buffets and salad bars, present a significant challenge to food safety because the food is exposed to the public. ServSafe Manager guidelines require that these areas be monitored by trained employees primarily to preventaccidental or intentional contaminationby customers. Unlike a controlled kitchen environment, customers in a self-service line may not be aware of food safety protocols. Common risks include customers using the wrong utensil for a dish (cross-contamination of allergens), returning to the line with a "dirty" plate for seconds (introducing saliva or bacteria from their previous meal), or children touching the food or sneeze guards.

The presence of a food handler acting as a monitor is a critical "Active Managerial Control" measure. This employee’s role is to ensure that sneeze guards remain in place, that utensils are kept in the food with handles pointing out, and that customers follow proper hygiene practices. If a customer is seen contaminating food—for example, by using their hands or sneezing near the display—the monitor must immediately remove the contaminated product and sanitize the area. While helping customers select food or preventing "food theft" may be secondary tasks, the primary safety objective is to protect the integrity of the food from biological, physical, and chemical hazards. The FDA Food Code specifically mandates that "effective measures" must be taken to protect food in self-service areas, and dedicated monitoring is often the most effective method. Furthermore, the monitor ensures that the food remains at proper temperatures (135°F or higher for hot food, 41°F or lower for cold food) and that the "First In, First Out" (FIFO) method is used when replenishing items.