You cannot know that. Not at all. The beakers are clean as possible right now. You see the thick white paper on the tables? That is changed after every brewing batch.
ALL labs brew in open air environments, very few have over head fans like I do and NONE of hepa filtration
As long as you filter it right, use the right about of BA/BB and your vials, stoppers and caps are sterile and produced wearing sterile gloves in a clean environment (you could even do it in your kitchen under the kitchen fan like home brewers do and that would be sterile enough) I go over kill. There is zero chance of uncleanliness or something ending up in the finished product that should not be there.
AND we use an autoclave, home brewers use toaster ovens... If my gear was not sterile word would be out and I would have caught infections many years back