Some chemicals can be detected easily by smell initially but can then cause
olfactory fatigue or the loss of ability to smell the substance. H2S causes olfactory fatigue and
causes paralysis of the olfactory nerves.
Relying on sense of smell can provide a false and potentially fatal sense of security with
an extremely toxic gas. Never use your nose as a quantifier of chemical concentration or
as a device to determine whether or not the air is safe.
| Material |
Odor Threshold (ppm) |
PEL (ppm) |
| Acetone |
62 |
1000 |
| Ammonia |
5 |
50 |
| Hydrazine |
3.7 |
1 |
| 1,1,2 -
Tricholoroethelyene |
82 |
100 |
| Methyl Formate |
2000 |
100 |
| Hydrogen Sulfide (H2S) |
0.3 |
10 (ceiling limit) |
|
