To be clear and EMP has nothing to do with allergen cross contamination (at least under SQF) and everything to do with pathogens
Environmental Monitoring
A risk-based environmental monitoring program shall be in place for all food manufacturing processes and immediate surrounding areas, which impact manufacturing processes.
The responsibility and methods for the environmental monitoring program shall be documented and implemented.
An environmental sampling and testing schedule shall be prepared. It shall at a minimum:
i. Detail the applicable pathogens or indicator organisms to test for in that industry;
ii. List the number of samples to be taken and the frequency of sampling;
iii. Outline the locations in which samples are to be taken and the rotation of locations as needed; and
iv. Describe the methods to handle elevated or undesirable results.
Environmental testing results shall be monitored, tracked, and trended, and preventative actions (refer to 2.5.3.1) shall be implemented where unsatisfactory results or trends are observed.
What your talking about is VALIDATIONS of your allergen free facility
A simpler way to control allergens in your facility is to get COA with every shipment of ingredients and/or a statement from the manufacturer about how they control allergen introduction at their facilities
If your swabbing in house, it would be because you believe that allergens are being introduced somewhere along your supply/process chain, that should be controlled using other methods
Allergen swabbing is usually done to ensure no cross contamination in facility that do process some products with an allergen(s) and some without