Bacterial contamination of confined, sealed space during long-term human occupation.

The long-term presence of human beings in a closed room of small volume is accompanied by the accumulation of a common and hemolytic microflora on their bodies, clothes, in the air, and on the room surfaces. A study was made of the dynamics of the spreading of such microflora in rooms measuring from 5-21 m3 when occupied by 1-3 persons for 5-30 days. With minimal sanitation the skin, after 30-40 days, is covered with several thousands of microbes per cm2, of which the hemolytic staphylococci amount to about 500 cells per cm2. Linen contained tens of thousands of bacteria per cm2, including up to 7000 hemolytic staphylococci per cm2. Generally, air contamination increases during the experiment. The rate of increase depends on many factors, and includes, in addition to common microbes, hemolytic staphylococci, streptococci, including pathogenic ones. The distribution of microbes in the air depends on human activity, and the total number is lowered by improved sanitation. While initial surface contamination depends on preliminary disinfection, there is a steady accumulation of micro-organisms on the chamber surfaces. No Escherichia coli could be found on chamber surfaces. Most bacteria were found on horizontal surfaces, working areas and floors (thousands of microbes per cm2), while ceilings and walls yielded from units to hundreds of cells per cm2.