Respiratory
and inhalation hazards on fire scenes
By
Alan Perry
August
30, 2014
Smoke
is a complex and dangerous by-product of combustion presenting many dangers to
firefighters and building occupants during and after a fire event. The most
obvious concern is during the fire where super-heated gases loaded with toxins
and asphyxiants can enter the airway & lungs causing immediate acute
respiratory problems. These are well understood as are the dangers of post-fire
exposure to carbon monoxide and cyanide, but this is only the tip of the
iceberg so-to-speak. I would like my comrades to consider a fuller disclosure
about the dangers of post fire exposure to the other asphyxiants, irritants,
chemicals and particulates that are also present during overhaul, investigation
and recovery stages that we do not routinely monitor. I believe many are lulled
into a false sense of security by the lack of information about the harm caused
by, and technology for measuring these harmful agents. Consider the typical
fire where the scene is declared safe for removal of SCBA because of a low
level of carbon monoxide. What other agents may be present? What are the
compounded effects of multiple agents’ short term and long term? If a
firefighter or citizen has detectable levels of CO in their bloodstream and/or evidence
of cyanide exposure, what other agents have they also been exposed to? The
by-products of combustion are not always present in a recognizable form such as
smoke; they can linger for hours or days in the debris and residue at a fire
scene and on tools and turnout gear. Just because you can’t see it does not
mean it is not there.
The
compounds present in the post-fire environment include asphyxiants, irritants,
complex compounds and particulates. Most of these are present in all fires; the
exact composition will depend on what is burned and how it burns. The
transition in home construction and furnishings, as well as items kept in
storage areas such as garages and sheds can yield a very wide variety of
harmful agents when burned. This makes it virtually impossible to predict exactly
what, or how much, is present in any given fire event. As I stated earlier,
most every firefighter is aware of the dangers associated with CO and cyanide,
we talk about these a lot, and we have tools to measure and treat the effects
of these. Now let’s look at the “other stuff”
Asphyxiants- these compounds interfere with
transport of oxygen in the blood stream and use of oxygen by target tissues or
displace oxygen, causing hypoxia.
Substance Source effects begin
·
Carbon Monoxide (CO) incomplete oxidation of
organic fuels
·
Hydrogen Cyanide (HCN) organic fuels containing carbon
& nitrogen <130ppm
·
Carbon Dioxide (CO2) organic fuels
·
Oxygen deficient atmospheres
Irritant gases- these compounds irritate and in
many cases damage the airways and lung tissues reducing their ability to
function and causing pulmonary edema and introducing toxins.
·
Hydrogen chloride (HCL) plastics, polymers, PVC 35
ppm
·
Hydrogen bromide (HBr) synthetic polymers, flame
retardants 5 ppm
·
Hydrogen fluoride (HF) fluorinated synthetic
polymers 0.5
ppm
·
Sulfur dioxide (SO2) fossil fuels,
rubber, tires 0.4
ppm
·
Nitrogen Oxides (NOx) any combustion in
ambient air 20 ppm
·
Phosphorous pentoxide (P2O5) electrical components, flame
retardants n/a
·
Acrolein wood,
cotton, paper 0.5
ppm
·
Formaldehyde wood, cotton, polymers,
plastics 0.1
ppm
·
Ammonia (NH3) wood, coal,
paper, household waste 50 ppm
·
Chlorine plastics,
polymers, synthetic rubber 1 ppm
·
Phosgene (COCL2) chlorinated compounds,
plastics, polymers 3 ppm
Complex
molecules- long
carbon-chain and carbon ring compounds. These compounds can have acute effects and
are known carcinogens & mutagens, in addition to their irritant and toxic effects.
Several have delayed onset of symptoms.
·
Polycyclic aromatic hydrocarbons (PAHs) organic materials n/a
·
Dioxins/Dibenzofurans PVC, PCB, plastics n/a
·
Isocyanates polyurethane foam &
plastics 1
ppm
·
Perfluoroisobutylene (PFIB) PTFE, fluorine containing polymers n/a
·
Particulate matter
The sources of these materials are not
unusual, therefore nearly all of these agents can be found in varying
concentrations during and after a fire event. The interactions and effects on
the human body are still largely unexplored but clearly are likely to affect
the health of those exposed. The effects may be delayed for hours, weeks or
years and the cumulative effects will be even harder to predict.
Firefighting causes a great deal of
stress on the body from the combined effects of hyperthermia and physical
stress causing profound changes in physiological function, particularly with
the circulatory system. Firefighters experience coagulopathy for up to two
hours after a fire event, in this state the blood does not clot properly even
when properly hydrated. When you are exposed to smoke, injuring lung tissue and
poisoning the circulatory system with toxins, it is easy to see why we suffer
cardiovascular problems and death.
Something to think
about before you pull your face
piece off next time.
References:
Wakefield,
J.C., A Toxicological Review of the
Products of Combustion, Health Protection Agency, 2010
Demling,
Robert H., Smoke Inhalation Lung Injury:
An Update, Harvard Medical School, Burn Trauma Center, 2008
