Prevention of Inhalation Injuries

In the emergency response professions there are many examples of inhalation exposures to combustion gases and even chemicals.


Chief Montagna stresses to use our educated noses when we search for the source and to become good detectives. Interview appropriate people that can assist with the identity of the odor's source. Also, return to fresh air periodically to freshen your sense of smell. Remember too, to utilize thermal imaging cameras to assist with finding hot spots that may be sources for odors. Finally, Chief Montagna warns to not give up when looking for smoke or electrical odors; your efforts may save lives. With all of these investigations be wary of any and all inhalation exposure!

Chemical
Anhydrous Ammonia
Benzene
Butyric Acid
Carbon Disulphide
Chloroform
Chlorine
Hydrogen Cyanide
Naphthalene
Phenol
Phosgene
Styrene
Toluene Diisocyanate
Odor
Pungent
Solvent
Vomit
Rotten Cabbage
Sweet
Bleach
Bitter almonds
Moth balls
Medicinal
New mown hay
Solvent, rubbery
Medicinal, pungent

Chemical Odors

One warning of chemical exposure we can use is the sense of smell. Many chemicals do have strong odors but be cautious because awareness of their presence may cause over-exposure. Some well-known chemicals with distinct odors are listed below;

Also, it is important to keep in mind that some chemicals do not have detectable odors or may have poor warning properties. These materials are very dangerous to unprotected responders because over-exposure may not be noticed until toxic effects become apparent. Effects include dizziness, confusion, slurred speech, and nausea. Some of those materials are listed below;

Chemical
Carbon monoxide
Hydrazine
Hydrogen sulfide
Methane
Methylene chloride
Propane
Odor
None
Ammonia odor, poor warning properties
Rotten eggs, cautious of olfactory fatigue
None, odorant added for detection
Sharp, ether smell, poor warning properties
None, odorant added for detection

Additionally, some chemicals may be detected through the sense of smell only to "disappear" a short time later. This happens because of olfactory fatigue. The chemical may still be present it just cannot be detected by smell. Chemicals that cause olfactory fatigue and those that cannot be detected by smell must be regarded as serious threats to responder health and safety. The only method of reliably detecting the presence of such chemicals is with properly selected and maintained monitoring instruments.

Odor Thresholds

Many of the chemicals that have odors possess what is called "odor thresholds" or a range in which the average person can detect their presence through the sense of smell. There are many sources of this information but one source that has spent millions of dollars researching and developing a respirator guide is from the 3M Company. The alphabetical listing of chemicals in the guide was developed to assist respirator users in selecting the proper respirator for use in specific chemical environments.

Up until 1998 it was permissible to use odor thresholds to indicate when cartridge type respirators had reached the end of their service life. It is called "breakthrough" when the wearer can detect the chemical odor inside the respirator. An exit of the area and a cartridge change would be in order. A rule change by OSHA in 1998 now prohibits using breakthrough as the end of service life indicator because it has been found the odor threshold range was not reliable. One worker may smell the chemical breakthrough much sooner than another worker so this individual difference may lead to over-exposure. Obviously, breakthrough is not a concern for responders who wear scba's.

Odors and odor thresholds for specific chemicals may also be found in MSDS's. As for investigations particular odors may assist responders in quickly identifying the source and hazard in order to avoid exposures. Some private industries even have their employees sniff samples of chemicals in order to better detect them in the event of a release. The table below lists many chemicals, their odor, and both the pre-1998 odor threshold range along with the post-1998 odor threshold that can now only be used as a reference.

Chemical

Anhydrous Ammonia
Benzene
Carbon Disulphide
Chlorine
Chloroform
Hydrogen Cyanide*
Hydrogen Sulfide
Methanol
Naphthalene
Phenol
Phosgene
Styrene
Toluene
Odor

Pungent
Solvent, aromatic
Rotten Cabbage
Bleach
Sweet
Bitter almonds
Rotten eggs
Poor warning
Moth balls
Medicinal
New mown hay
Solvent, rubbery
Medicinal, pungent
Threshold(PPM)
1995
.043-53
34-119
.016-.42
.08
133-276
.1-5.0
.0001-.13
4.2-5960
.038
.006
.12-5.7
.017-1.9
.17-2.0
2001
5.75
8.65
.096
.05
11.7
.603
.0005
141
.015
.011
.55
3.44
2.14
Only half of the population can detect the odor of HCN because of genetic reasons.
Source; 3M Respirator Selection Guide
Available through Occupational Health & Environmental Safety Division at 800-243-4630