Forest fires are something straight out of Dante’s worst nightmare. Flames hundreds of feet high, heating the air to blast furnace temperatures (1,500 degrees F).
Anything in the path is superheated until it bursts into flames. The tormented air forms whirlwinds of burning debris – a tornado of fire. The forest fire is so furious, it can take weeks or months to control.
We speak of control because forest fires cannot be vanquished; only contained with an immense amount of effort by many heroic people, and cooperative weather.
And there is smoke. Smoke so dense that visibility can drop to zero. Smoke that can darken the skies for as far as the eye can see. For those of us not fighting fires, our health concern is the exposure to smoke.
Wildfire smoke is a complicated mixture of gasses and particles. Its composition depends on the heat of the fire, and what is burned. Common to all smoke is carbon monoxide, which is in high concentration close to the source. This quickly dissipates once the smoke has mixed with air. “Dilution is the solution to pollution,” as my organic chemistry professor used to say in 1978.
There are many irritating chemical compounds in smoke. Acrolein and formaldehyde are both known to trigger asthma attacks. These chemicals are difficult to filter without sophisticated equipment, so an abundance of caution is advised, particularly for those with asthma. If you are near a wildfire, remove yourself from smoke. If that’s not possible, stay indoors with all windows closed and the AC/air cleaner running.
The solids in smoke are a concern due to their extremely small particle size (2.5 microns, or 1/25 the diameter of human hair). These particles can easily pass through a paper mask sold at the local hardware or drug store. They travel deep into the lungs. The lung anatomy is tree-like, and all the work of gas exchange occurs at the alveoli, which is the lung’s equivalent of a tree leaf. These are delicate structures that are easily damaged by microscopic carbon deposits. This can create inflammation, which can progress to temporary or even permanent decrease in lung function.
Smoke exposure may manifest early as bronchitis with a productive cough or wheezing. Treatment is symptomatic: an inhaler for wheezing and perhaps antibiotics or steroids for inflammation or secondary infection. Fortunately, almost everybody recovers from a several-hour lung assault with smoke.
This particle is also a known risk for the heart. This information comes from long-term air pollution studies. Particles of virtually anything, in the size range of 2.5 microns, put stress on the heart. The mechanism for this is not totally figured out, but it’s probably heart artery damage due to inflammation. Existing heart disease, which can be silent, can be worsened by smoke with particles in this size range.
Smoke, we all know, should not be breathed. Unless the forest fire is in a tobacco farm, it is not addicting. Casual exposure to distant forest fire smoke is a very low-risk activity to the normal healthy person. But those with fragile lungs or hearts should be cautious and avoid smoke as much as possible.
Donald Bucklin, MD (Dr. B) is a Regional Medical Director for U.S. HealthWorks and has been practicing clinical occupational medicine for more than 25 years. Dr. B. works in our Scottsdale, Arizona clinic.