Cristobal Huet made 27 saves in taking the loss. Chicago has dropped three out of four.
St. Louis owned a 16-3 shot advantage in the opening period, but did not score until 1:55 remained in the stanza. Woywitka fired a blast that trickled through Huet's pads.
It was Mason's 14th career shutout and his second with the Blues.
Wisconsin business offering 'therapeutic cuddling' forced to close
N.J. man wakes up from 10-hour sleep with knife in back