The wand will be useless unless they hold it above the area for 30+ seconds, which probably won't happen. Or unless the light is extremely intense which sounds dangerous.
I tested this at work. 222nm, 265nm, 275nm, 290nm. Petri dishes colonized with human underarm flora were prepared, closed, then incubated for an hour at 80F. tested times were 30 seconds, 60 seconds, 2 minutes, 3 minutes, 5 minutes.
222nm doesn't take even 30 seconds to wipe things out. Every dish was totally clean.
265nm needed about 2 minutes to sterilize.
275nm almost got the job done at 3 minutes and had the 5 minute dish totally clean.
290nm was frankly pathetic. All of the dishes survived with barely-decreasing colony count across increasing times. I estimate it'd take an hour of exposure to clean the dish.
