Mask wiggling as a potential cause of wound contamination.

Some operating-theatre staff have a habit of wiggling their surgical masks by moving their facial muscles. The field contamination which can result from this practice was studied. A firmly fitting, moulded, synthetic-fibre mask produced significant bacterial contamination of culture plates held beneath the mask, compared with that found on simultaneously exposed control plates placed nearby. Softer fibreglass masks produced less contamination when moved by facial muscles, and are more suitable for mask wigglers.