Molds in house dust, furniture stuffing, and in the air within homes

1.1. The mold colonies isolated from 76 samples of house dust collected in homes in and near St. Paul and Minneapolis, Minnesota, in the winters of 1950 and 1951 to 1952 varied from less than 10,000 per gram to more than 3,000,000 per gram. with an average of 179,966 mold colonies per gram. 2.2. The number of bacteria from 14 samples of house dust ranged from 1,144,000 to 20,000,000 per gram, and averaged 10,700,000 per gram. 3.3. Molds and bacteria were present in some numbers in the samples of new furniture stuffing, and were present in considerably greater numbers in some used materials. 4.4. Foam rubber appears to be somewhat susceptible to invasion by molds, though to a lesser degree than certain fibers. Bacteria do not appear to be present in any considerable numbers in either new or used foam rubber. 5.5. The molds present in the air within homes may differ in both kind and numbers from those in the outdoor air at the same time. The number of viable mold spores (or other inoculum) in the air within homes may fluctuate sharply during a single day, apparently increasing when the amount of physical activity within the home increases.