THE DANGER OF SMOKE
We tend to picture barns as wooden structures inside
and out—the kinds of barns seen on century-old farms and older boarding stables—and
there was a time when wood, hay and straw were the main fuel in barn fires. Where
once the items in a barn were produced from “natural” materials such as leather,
iron, cotton, wool, and rubber, now we rely so heavily on plastics that we
have nearly ceased to be aware of these potential hazards and the toxic byproducts
that may be released or formed in a fire.
We have more
plastic and petroleum-based products in our barns nowadays than we realize, and
in a fire the gases produced by some plastic products can be highly toxic. If you
still have that picture of a wooden barn in your mind, look around your current
barn. You probably have plastic feed tubs, plastic water buckets, nylon hay bags,
nylon halters and lead ropes, nylon saddle bags, plastic stall signs, horse ball
toys, grooming tools, and plastic (bless the person who invented these) manure
forks. And don't forget the plastics used in packaging medications and supplements,
feed bag liners, bagged wood shavings, and even plastic baler twine.
With that in mind, I'd like to start this section with an excerpt from an somewhat scholarly article I wrote about 20 years ago:
"The greatest danger to life in fires are the gases and smoke produced by the burning materials. Smoke has a visible component and an invisible component. The visible component, particles of matter in varying sizes, is dangerous because it cuts down or completely blocks vision, slowing or stopping the evacuation of occupants from a burning structure.
The gaseous component is dangerous because it contains substances that can kill. Carbon monoxide (CO) and hydrogen cyanide (HCN) are the two most common fire gas constituents. It is generally well-known that carbon monoxide is lethal and is present in all fires. In the bloodstream, where carbon monoxide displaces oxygen, the presence of carboxyhemoglobin (COHb) in levels equal to 50% or more of total hemoglobin is considered lethal. A check of the COHb level in a victim's blood is usually the first step in determining the cause of death in a fire. Hydrogen cyanide appears to add to the toxic effect of carbon monoxide in interfering with oxygen transport and metabolism. Hydrogen cyanide is also commonly found by direct analysis at autopsy.
The first realization that toxic combustion products previously unknown might imperil lives came with the Cleveland Clinic fire on May 15, 1929. In that fire, the newly-developed product, nitrocellulose ex-ray film, played a major role. No one is positive how the fire started in the hospital's basement where the x-ray films were stored, but when firefighters arrived, poisonous yellow gas fumes given off by the burning films were filling the clinic building. People inside were quickly overcome, and when windows burst, people on the street were also overcome by the toxic smoke. Firefighters attempting to enter the building were driven back by the gas fumes. Firefighters with hose lines literally cut through the smoke to keep flames away from their fellow firefighters who were trying to resuscitate victims. The gas from the films did not claim all its victims immediately; some people walked out of the building in good condition only to die hours or even days later."
Carbon monoxide is often the largest component of smoke. It’s
a colorless, odorless toxic gas that is a product of incomplete combustion. When
carbon monoxide is breathed in, it takes the place of oxygen at a rate of
300 to 1 and actually suffocates its victim. Even at low levels, over
a period of time, it can be dangerous.
My husband and
I experienced one of the earliest signs of carbon monoxide poisoning one night
while driving home in my husband’s fairly new 1976 Cadillac. We were on
a perfectly smooth road when my husband gave a groan of disgust and said
we had a flat tire. I hadn’t felt any change in the car’s behavior. We both got
out and saw that all the tires were fine. I offered to drive, and got behind the
wheel. Within a couple of minutes, I felt the car lurching as if a tire was flat! By
that time we were at our driveway, so I parked the “crippled” car in the garage
and once more we checked the tires and found them to be fully inflated. We
decided we couldn’t both be crazy, so the next morning my husband took the car
in to be checked (he drove with all the windows down) and sure enough, an inspection
found that exhaust fumes were seeping into the passenger compartment on the driver’s
side! That’s why each of us had become disoriented when we drove, and
through the power of suggestion, why I was also sure a tire was flat.
In addition
to disorientation, such as we experienced, other first stages of carbon monoxide
poisoning can be flu-like symptoms, dizziness, weakness, nausea, vomiting, a headache
or throbbing at the temples, some loss of muscle control and an increase in pulse
and respiration.
In the middle
stages, the victim will be conscious but very confused and may not be able to move
due to muscle weakness.
In the final
stages of carbon monoxide poisoning blood pressure falls, muscular control is lost,
reflexes are dulled, and there may be convulsions. Then breathing grows shallower
until it finally stops.
Now,
imagine yourself or another person or an animal in your barn suffering from these
symptoms when no fire is present, but perhaps, you're operating a tractor in the barn. If you notice a person or animal who is behaving
oddly, or you begin to have symptoms yourself, get everyone involved out
to fresh air immediately.
You now realize that carbon monoxide is the part of smoke
you can't see. The part of smoke you can see has three main effects on your
body (and your horse's body): eye irritation; narcosis (loss of consciousness);
and respiratory damage.
Smoke reduces visibility, which slows you down, making
your evacuation take longer, exposing you and your horses to the toxic products
of smoke for a longer period of time. Smoke causes nerve endings in
the cornea to react, causing pain, blinking, and tearing. Shutting your
eyes to ease these effects definitely impairs the speed of escape.
A narcotic, medically-defined, is a drug that causes unconsiousness
(narcosis) and loss of the sensation of pain. When referring to fires,
however, narcosis refers mainly to toxic gases that can result in central
nervous system depression with loss of conciousness and finally, death. Depending
upon the concentration of such irritant gases in the smoke, your evacuation
efforts can be impeded by the early stages of narcosis which result in disorientation. If
either you or the horse you are attempting to evacuate become disoriented,
the chances of your successful evacuation are poor. That's one
extremely important reason to obey immediately any orders given to you by
firefighters. If the smoke becomes too great a hazard and you are ordered
to abandon evacuation, the order has been given to protect your life.
Firefighters
are aware that many toxic substances may be found in occupied structures in the
form of cleaners, polishes, chlorine bleach, ammonia and pesticides. They
also face dangers that they may or may not know about beforehand such as oxygen
cylinders used for respiratory illnesses, fireworks, powder and caps for shotgun
shell reloading, and even materials for illicit drug manufacturing. These
are just a few of the hundreds of unexpected perils firefighters encounter in fighting
structure fires. One constant factor, though, is the production of toxic
gases from burning contents. It’s now standard practice for every firefighter
entering a burning structure to be using self-contained breathing apparatus (SCBA),
and very often SCBA must be used by those outside but in close proximity to the
burning structure.
Lung irritation produces coughing and bronchial
constriction with resulting tissue inflammation and damage. Death often
follows exposure to high concentrations of irritant gases, usually after 6
to 48 hours, as happened in the Cleveland Clinic tragedy. One reason we are
so prone to lung irritation is that we have a tendency to be mouth breathers,
especially in stressful situations like a fire. By not breathing through
our noses, our bodies can't take advantage of the cleaning ability of our
nasal passages. Coughing,
as a protective mechanism, also slows down our escape because it's extremely
difficult to lead a horse and have a coughing fit at the same time, even
on a clear day when the sun’s shining.
All of this information points to one factor: time is
of the essence when it comes to evacuation, not just to escape the heat and flames
but to escape the equally dangerous smoke.