ultraclean

From ultra- +‎ clean.

ultraclean (comparative more ultraclean, superlative most ultraclean)

1. Exceptionally clean.
   • 2009 January 27, Jane E Brody, “Babies Know: A Little Dirt Is Good for You”, in New York Times:

     "Children raised in an ultraclean environment," he added, "are not being exposed to organisms that help them develop appropriate immune regulatory circuits."