Fire and Smoke Damage
What Causes Death from Fires and What is “Burning”?
Forest fires have burned hundreds of thousands of acres and thousands of buildings in recent years. The greatest loss is in the lives of both humans and wildlife. The number one cause of death related to fires is smoke inhalation (airway or pulmonary parenchymal injury). Smoke inhalation occurs when you breathe in the products of combustion during a fire – the harmful gases, vapors and particulate matter (soot, etc.) contained in smoke. Combustion produces these gases, vapors and particulate matter that results from burning, or the rapid breakdown of a substance by heat.
The exact composition of smoke produced by any individual fire cannot be predicted because of different temperatures, the products being burned in the fire and the amount of oxygen available to each individual fire.
Note that cigarette smoking causes similar damage on a smaller scale over an extended period to the human body. The primary source of injury in the upper respiratory tract is heat, but within the lung it is the deposition of particles, derived from the products burning, together with toxic gases given off by the fire. The combination of heat and toxic substance inhalation can be lethal.
How Smoke Inhalation Damages the Body
The harmful materials given off by combustion injure the airways and lungs by: (1) heat damage; (2) tissue irritation by irritant compounds and (3) oxygen starvation of the tissues defined as asphyxiation. Remember that smoke inhalation victims may not show injury symptoms until 24-48 hours after the inhalation event. Also, children under age 11 and adults over age 70 are most vulnerable.
The degree of heat involved in the fire creating the smoke is directly related to the seriousness of potential damage from smoke inhalation. According to W.R. Clark, Jr., “The mortality rate of smoke inhalation victims without a burn is <10%. With a burn, the mortality rate is 30-50%, suggesting that thermal injury or its treatment is responsible for further lung damage.”
The primary source of injury in the upper respiratory tract is heat, but the thermal injury does not usually extend beyond the bifurcation or forking of the trachea (commonly known as the windpipe). Within the lung the particulates, or particles of matter resulting from the combustion, combined with the toxic gases, cause the majority of damage in what appears to be a response to stimulation of the inflammatory response.
Smog particulates can create a similar irritation, but are derived from other environmental particulates such as auto emissions and industry pollutants. Unless this particulate matter is removed, the continued presence may lead to damage and an impaired respiratory function.
While we focus on external defenses from equipment to chemicals and trained personnel, internally your immune cells are the first-line defense mechanism. The primary function of the white leukocyte immune cells, known as alveolar macrophages in the lungs, is to engulf and dispose of any matter, especially smoke, entering the lungs not produced by the body (non-self) – a process described scientifically as phagocytosis.
The function of these large white immune cells is part of the innate immune response of the body. For the body to be able to fight back successfully against the soot, carbon and other particulates from the smoke inhalation and smog, these macrophage cells, or immune soldiers, must be in peak condition and not be suppressed or damaged.
If suppressed or damaged, the immune response cannot naturally dispose of the invasive and damaging pathogens in an orderly manner and the signs and symptoms of smoke inhalation, including asthma and severe respiratory problems, can occur.
Chemical asphyxiants from a fire can produce compounds that damage the body by interfering with the oxygen use at the cellular level. Carbon monoxide, hydrogen cyanide and hydrogen sulfide are all examples of such chemicals. Why is this so important? If either the delivery of oxygen or use of oxygen is inhibited, cells will die. Carbon monoxide is the leading cause of death in smoke inhalation for this reason.
What is known as simple asphyxiation refers to combustion using up all oxygen near a fire, which then leaves no oxygen to breathe. When you have no oxygen to breathe for even a brief period, lung and respiratory damage can occur and, if for an extended period, you die. Asphyxiation is recognized by shortness of breath, blue gray or bright-red skin coloration and in extreme cases by loss of consciousness or breathing.
Diagnosis of Smoke Inhalation Damage
In addition to inspecting for signs of heat damage, tissue irritation and asphyxiation, the attending medical personnel will assess the victim’s breathing by the number of breaths per minute (respiratory rate) and motion of the chest as the lungs inflate and deflate. The victim’s circulation is evaluated by the number of heartbeats per minute, or pulse rate.
The damage of fires, external and internal, can be life threatening and take decades if ever to totally overcome. Frankly speaking, be aware and practice safe actions to avoid fire damage both externally and internally.