"R Williams" (force4 at onlink.net) writes:
> what are unsafe levels of amonia indoors and when could you tell when levels
> are unsafe
Estimated LC values for human exposure to ammonia:
Exposure (minutes) LC50 (ppm) LC10 (ppm)
120 3,700 1,900
60 5,300 2,600
30 7,500 3,800
10 13,000 6,600
5 19,000 9,400
2 30,000 15,000
Give or take factors of two or so.
DISCLAIMER (which appeared in the source identified below): It
cannot be emphasized enough that these dose-lethality values are
based on few data and considerable speculation -- they should be
used predictively only with appropriate circumspection.
Source: Engelhardt, F.R. and Holliday, M.G., "Dose-lethality
Relationships of Acute Exposure to Anhydrous Ammonia",
Report No. INFO-0153. Ottawa, Ont.: Atomic Energy
Control Board (1 March 1985).
And, if memory serves, the ACGIH TLV(R) is 25 ppm.
The odour threshold is of the order of 10 ppm and, I am assured on
good authority, concentrations above 400 or 500 ppm cause
noticeable discomfort in the genital area (especially if one is
hot and sweaty :-). Of all mammals, bats seem the most resistant
to ammonia and appear to tolerate atmospheric concentrations of 3000
to 5000 ppm without adverse effects.