Volume I - Section III - Evaluation of Results and Recommendations 
Page III - 45 
Figure 3.61 Comparison of Room Day 4 NH 3 Concentrations 
3.2 NH 3 Concentrations for 10-day cycle 
Table 3.03 shows a summary of mean and maximum NH3 concentrations in the room’s breathing 
zone over 10 days using the different generation rates measured in the experiments. In the 
summary, values between 0.5ppm and lppm have been colored blue, and values above 1 ppm are 
colored red. Smyth (1956) found lppm detected and identified by 10 subjects. In addition, 
analysis of data obtained in plant surveys conducted from 1965 to 1970 by the Bureau of 
Industrial Hygiene, Detroit Department of Health, found the limit of detection to be below 5 ppm 
and the complaint level to be 20 ppm to 25 ppm. Therefore, lppm was chosen as a conservative 
level at which people might be able to detect a smell in the room. 
With the exception of the very low flow rates (5 ACH) for the double density rooms, all the 
room configurations show an acceptable NH3 concentration, on average, in the breathing zone up 
to day 5. The maximum value in the breathing zone, present in just one small location, is 
generally all right up to day 5. By day 5 and day 6 virtually all rooms had at least one spot above 
lppm. This indicates that changing the bedding every 5 days should leave most rooms with an 
acceptable atmosphere. 
Table 3.04 shows a summary of mean and maximum NH3 concentrations in the cages over 10 
days using the different generation rates measured in the experiments. In the summary, values 
over 25 ppm have been colored red, as such high levels are likely to cause problems for the mice. 
