Friday, August 29, 2014

Field Expedient Disinfectants


At least four trends are colliding that will amplify the panic and mortality rate of the future epidemics in the United States.  
  • Our borders have become more porous and even the poorest nations have international airports
  • Medical care has been industrialized.  Cost centers have been rationalized and profit centers have been bloated.  The underlying assumption is that civilians will step up and take on roles they have not been trained for.
  • Emerging diseases generate vast amounts of infective material.  Somebody once likened a patient with Ebola to a slug that has been sprinkled with salt.
  • Social media has turned very citizen over the age of 8 into a shrieking tabloid spewin emotional gibbering devoid of useful information.



You get up at 5:30 in the morning.  You drink two cups of coffee and get in your vehicle.  You fight traffic for 65 minutes to get to work.  You are two hours behind from the second you walk through the door.  It is non-stop chaos as you battle your way through the day.  Because you are conscientious you stay over an extra couple of hours to help get the next shift off to a good start.  Your usual 11 hour shift became a 13 hour shift.  You drive home through the light, late evening traffic.  While it was a long day, so far, there has been nothing unusual or special about it.

Once home you crack open an  adult beverage and turn on the last bit of TV news. 

And then you learn that a foreign exchange student at a high school three zip codes away is in an isolation ward at the University hospital.  The student flew in from Accra, Ghana a week ago and has symptoms that are consistent with Ebola.

You decide this might be a good time to hit the local convenience store and buy a spray can or three of disinfectant.

They have no disinfectant left on the shelves.

Since you are already out of the house you decide to drive down to the big-box store to buy a dozen cans of spray.  They are also wiped out.  It looks like a bomb hit the aisles of the pharmacy.  You curse the social media that has generated the panic and has you the last person in-the-know.

What to do?

A couple of pieces of background information.

Liquid disinfectants are severely limited.  Two of the biggest problems are "the particle problem"   and "the contact time" requirement. The two problems are related.

I have had conversations with Doctors of Veterinary medicine and they poured out their heart and soul.  Few people realize that it can take hours for an antiseptic solution to penetrate infected particles.  Particles are found in vomit, fecal materials, clotting blood and other body fluids especially if it has soaked into fabric or bedding.  Hypodermic needles jammed with tissue or clotted blood are also a challenge for solutions to penetrate.

Most commercial products are formulated with detergents to assist in wetting-out and with pH buffers to keep the solution in the "sweet spot" for the active ingredient.  Those enhancements help but do not eliminate "the particle problem".

My vet buddies strongly advocate that cleanliness is next to Godliness.  The best solution to "the particle problem" is to eliminate the particles.  They recommend power-washing surfaces before attempting to sanitize them. Otherwise you are fighting physics.  Then, saturate the surface with your disinfecting solution.  Then spray it some more.  You want it running off.  Wait a bit.  Wipe it off.  Then spray it again.  Disinfecting solution is cheap.  Your health is not.

Caveat:  This essay is focused on killing viruses

A commonly accepted level of efficacy for killing microbes is (5 log 10).  That is, for every million active microbes before treatment, only ten are viable after the treatment.  Another way to visualize the epic nature of a (5 log 10) event:  If the City of Los Angels, California had a (5 log 10) depopulating event, the survivors would be able to very comfortably fit inside a standard sized school bus.

Virus, in general, are not that hard to kill.  They are small and fragile.  Hepatitis is one of the tougher virus to kill.  For that reason it is probably the most common benchmark.  The viral equivalent of the white lab mouse if you will.

Your options


Many people have one of these turkey friers tucked away somewhere.

Oldest and best way.  It should be your first option.  Heat is very robust with respect to "the particle" problem.  Put it in a pot and bring it to a boil.  Boiling means -never- having to say "I'm sorry."   At least for viruses.


Virus are fragile and easily ripped up by Ultraviolet light.  The problems occur when viruses are embedded inside particles or folded up fabric or are in turgid or opaque discharge.

Fortunately, clothing that is hung on  a line will blow in the breeze.  Also the orientation of the sun will change throughout the day thereby exposing many aspects of the clothing and/or bedding to sunlight (UV).  Line drying objects is not a reliable way to get the Five Log reduction but line drying in direct sun for an entire day is a good second step to backstop chemical methods.  It can also help dissipate odors.

Bleach and water


The old stand-by.  One part bleach (standard 5% sodium hypochlorite) and nine or ten parts water.  Cheap, insensitive to temperature and pH.  Tough on skin and delicate clothing, corrosive to metals and both the stock solution and the dilute have a finite shelf life.  A minimum of a ten second contact time for all disinfecting solutions is recommended....and that is for a particle-free environment. 

Field Expedient:  Swimming pool shock chemicals.  To get the same concentration of the hypochlorite ions as commercial bleach one must use 20 ounces of 60% calcium hypochlorite per gallon or 32 ounces of 40% calcium hypochlorite.  If you want to skip the "stock solution" step you can replicate the 10:1 dilution by mixing 2 oz of the 60% calcium hypochlorite powder to a gallon of water or approximately 3 oz of the 40% dry powder.

Iodine and Polyvinylpyrrolidone (PVP) fall into this category.  Pretty much bulletproof but it stains and some people react to iodine.

Hand sanitizer

Typically 60% ethanol.

If you brought your vehicle you brought a disinfectant.

Field expedients:  Booze.  The CDC reports that ethanol's ability to function as a disinfectant "...drops sharply when diluted below 50% concentration, and the optimum bactericidal concentration is 60%–90% solutions in water."  That means that you need at least 100 proof booze (like Wild Turkey 101) if you are keeping it "for medicinal purposes."

Liquid isopropyl (rubbing) alcohol.  70 percent used straight-up out of the bottle.

Windshield washer solvent (typically methanol solution) is  a much weaker killer of microbes than ethanol or isopropyl alcohol but is better than wishful thinking.

Quaternary Ammonium compounds

Lysol and most other spray disinfectants.  Gentle.  Does not stain.  pH sensitive.  Has  a shelf-life issue after being diluted.  This is probably the picture you had in your head when you left for the convenience store.

Field Expedient:   Swimming pool algae control.  The swimming pool product typically has 10X the concentration of the commercial product.

Phenolic compounds

Field Expedients: Many of the "farm supply" disinfectants are compounded to include a phenolic compound.  Typically not as pH sensitive as the QACs and less sensitive to shelf-life issues.  These ag disinfectants are usually very cost effective.

Many mouth washes contain thymol which is a "phenolic" disinfectant.

There is evidence that tannic acid binds to the protein surfaces of viruses and can reduce their viability.  There is little data regarding concentrations required for effectiveness.  Oak leaves, tea leaves, willow bark are some sources of tannin.  Tannins are sensitive to minerals found in hard water, especially iron.


Formaldehyde, glutaraldehyde...these are the big guns.

Field expedient:  Some of the ag sanitizers.  This is the product that the Eaton Rapids Joe family uses.

Wood smoke.

If you can only remember one thing

Your local ag supply store is your best friend.  Commercial disinfectant concentrate (makes +100 gallons at standard dilution) for $23.  A gallon of iodine and a gallon of alcohol for $17 each.
Pray that you never find yourself in a situation where you actually need to use field expedient disinfectants.  But  if/when you do it is a safe bet that the actual situation will resemble a medical emergency in the calving barn or a boarding kennel more than will it resemble an episode from House.  Bring enough "gun".


A few good links



Detailed essay on the vulnerability of specific families of viruses to disinfecting strategies


  1. Thanks, a good idea to have 'something' on hand...

  2. Don't forget cider vinegar, a very useful disinfectant. I used to use it on open wounds in livestock, make a big bandage from paper towels and duct tape, wash the wound in cider vinegar, dab some on the bang-aid, then put it on the wound. I never had infections in my livestock. Horses look weird with a bid duct-tape bandaid, but they heal really nicely.

  3. We use a ton of the bleach solution to disinfect after being in the field. It's cheap, AND effective. But I'm only worried about HEP and HIV. Ebola is a whole other animal. Good information here and needed. Thanks Joe.

  4. Hello OldNFO, Thank-you for reading and thank-you for commenting. Enjoy your trip.

    Pawpaw: Thank-you for contributing. One of the fantastic things about the blog format is that intelligent discussions and civil dialog can spontaneously spring up.

    Brigid: I have NO doubt that you know way more about this topic than I do. One of the challenges of writing this kind of essay is knowing when to end it.

    We have all seen people at the gym think that they have effectively disinfected exercise equipment by wiping it down with a sort-of damp towellet. I will have succeeded if one person rethinks that approach on game-day and errs on the side of massive overkill.


Readers who are willing to comment make this a better blog. Civil dialog is a valuable thing.