Exterior doors or windows are properly protected except for the use of?

The use of cardboard as a protective measure for exterior doors or windows is inappropriate because it does not provide a reliable barrier against pests, environmental factors, or security threats. Cardboard can easily deteriorate when exposed to weather conditions, be damaged, or be removed altogether, making it an ineffective solution.

In contrast, options such as air curtains, automatic closures, and screens are specifically designed to enhance food safety by maintaining a barrier while allowing for ventilation or access. Air curtains create a continuous stream of air that effectively deters insects and other pests from entering, while automatic closures provide a means for doors to close behind individuals, minimizing the risk of contamination by ensuring that doors are not left open. Screens contribute by allowing airflow while keeping pests out, thus maintaining a safer and more sanitary environment.