No abstract

The levels of airborne contamination in various areas of two hospitals were determined during a 15-month sampling period, using Casella and Andersen volumetric samplers. Based on nearly 5,000 samples, the mean count per ft3 ranged from 4.5 in obstetric-gynecology delivery rooms to 72.4 in waste-handling areas. The mean count for the entire hospital environment was on the order of 20 contaminants per ft3; 48 % were associated with particles >5 u diam, 30 % with particles between 2 and 6 A diam, and 22 7c with particles <2 4 diam. The airborne contamination was influenced by traffic, activity, ventilation considerations, and gross surface contamination, but not markedly by seasonal changes. When suitable control measures were implemented, the level of contamination could be diminished and kept low.

A portable isolation box, provided with a filtered air supply and a means of access for a test subject's head, was attached to an Andersen Sampler and used to measure orally expelled bacterial contaminants before and after masking. This technique yielded more detailed quantitative information than was obtained by either sedimentation plates or Andersen sampling in an unconfined space. During talking, unmasked subjects expelled more than 5,000 bacterial contaminants per 5 ft;

No abstract

The microbial population (types and numbers) of a vertical profile of air in an industrial area of the Twin Cities was determined between May and November 1967. No consistent relationships could be shown to exist between the microbial contamination and the meteorological parameters concurrently measured. The mean viable counts ranged from 58/ft 3 at grade level to 22/ft 3 at 500 ft. Regardless of altitude, molds constituted approximately 70% of the total airborne microflora, bacteria between 19 and 26%, and yeasts and actinomycetes the remainder. The particle size with which the viable population was associated showed a consistent peak in the 3-5 JJ, range.