“…Since every human being carries an immense number of bacteria (Noble & Somerville, 1974), shedding from the upper respiratory tract, oral cavity, skin and hair of every person present in the operating-theatre will occur (Wells & Wells, 1936;Duguid & Wallace, 1948;Noble & Davies, 1965;Bethune et al 1965). Contamination of the air by these microorganisms is reduced by wearing a facemask, a cap and special clothing (Duguid & Wallace, 1948;Blowers & McCluskey, 1965, Bernard et al 1965Mitchell & Gamble, 1974).…”