Home Podcasts THMG025 – Decontamination, Part II

THMG025 – Decontamination, Part II


In this episode, Bob and Mike begin to discuss the different techniques we employ to decontaminate people, places, and things.

Complete Show Notes

4:35 Science Behind Washing

  • Understanding the science behind washing allows you to choose the right method
  • This series will discuss the types of decon (AKA the actual method of removing contaminated materials) and the methods of decontamination
  • Exposure
    • Difference between exposure and contamination – exposure is the product getting into your system
    • In radiation exposure, for example, the source gets into you and your biomass reacts with the radiation being given off
    • Once you’re exposed, there’s nothing you can do mechanically – at this point, you need to get medical help or take the time to see how the exposure will affect you
    • Avoid exposure by using PPE and SCBA; in radiation, avoid exposure by time, distance, and shielding

6:30 Absorption and Adsorption

  • NFPA 472 – gives a list of decon procedures that technicians must understand
  • Absorption
    • Think of absorption as sponging up a substance with sawdust, soil, oil, acid pads, sponges, towels, etc.
    • Hazardous material is removed from the person or object and then disposed of
    • Pros
      • Materials are generally cheap and easy to control, apply, or sweep up
      • Hazardous material isn’t changed, so we don’t have to worry about creating a chemical that we don’t know
      • Generally easy to collect because it’s in a solid form or trapped in another substance
      • Works great on tools because it’s easy to wipe off
    • Cons
      • Almost never used for personnel other than placing a few pads in front of a rig to wipe our feet
      • Doesn’t change the chemical properties – there are times when we want to change the properties to choose a method that removes the hazard of the material
      • Disposal can be highly regulated – make sure to choose a method that doesn’t generate a large waste mass to reduce disposal costs
      • Not all of the hazardous materials are removed from the object – not the best method if you need to get something really clean
  • Adsorption
    • When we adsorb, we are only using the SURFACE of the the absorbent – it doesn’t go into the adsorbent like a sponge does
    • Think of sand – sand doesn’t pull oil or water into its granules; instead, the oil or water sits on the surface and coats the sand, making it easy for us to pick it up
    • Pros
      • Just like absorption – materials are generally cheap and easy to control (or apply and sweep up)
      • No chemical change in material
      • Great for surfaces
    • Cons
      • Not used for personnel – no use for people
      • Disposal is highly regulated
      • It doesn’t get anything off

14:50 Solidification

  • A liquid is treated with a chemical that turns that liquid into a solid – the solid can then be picked up and over packed
  • Pros
    • Fast and easy for cleaning up spills
    • Doesn’t change chemical compositions
    • Easy to pick up and over pack
    • Great for large areas to prevent the flow of liquids
  • Cons
    • Cannot be used on people
    • Not meant to remove residue from tools
    • Doesn’t change the chemical, so the hazard may still be present
    • You have to make sure the solidifier and the product are compatible

16:45 Vacuuming

  • On the most basic level, you’re using a difference in air pressure to suck contaminants off of nouns
  • By nouns, we mean a person, place, or thing
  • We only use vacuuming on dry contaminants like powders, dust, and debris
  • Most “wet” hazards stick to surfaces and can’t be vacuumed up
  • Make sure everyone is using respiratory protection – vacuuming has the potential to kick the hazmat into the air
  • You have to use a special vacuum with HEPA filtration – important to filter anything more than .3 microns
  • Pros
    • Can be a fast and effective way of removing particulates
    • If done correctly, it minimizes waste products such as gray water or adsorbent materials
    • Excellent way to minimize radiation, cross-contamination, and waste
  • Cons
    • Requires special equipment and electricity
    • Only works with dust, fibers, and particulates – can’t be used with vapors or liquids

19:15 Chemical Degradation

  • Refers to breaking down a complex chemical into a simple chemical
  • Chemical degradation is really just an enhancement of a natural process
  • Many chemicals are unstable and will react over time to become something else – however, there are things we can do to speed the process up
  • Examples:
    • Ultraviolet light on H2O2 will cause it to break down much faster than it would naturally – this is why all H2O2 bottles are solid black or brown
    • In underground soil remediation, chemicals are injected into the earth to break the hydrocarbons down
  • RSDL (reactive skin decontamination lotion) pads are often used on people
  • Pros
    • Can be a very effective method when decontaminating areas or environments
    • Very little waste to dispose of since the bad stuff is broken down into harmless byproducts
    • Quick and proven process
  • Cons
    • Not really intended for use on people
    • You have to be very specific with the method being used – be 100% sure of what the contaminant is
    • Not really great for emergency immediate decontamination

23:35 Dilution

  • The process of reducing the concentration of a solute in solution – usually done by mixing with more solvent
  • This is what we do when typically discussing emergency or mass decon
  • We use regular water to wash off a substance
  • Pros
    • Fast and easy for firefighters because they have tons of hose
    • Can be performed even without a fire apparatus – you can use a garden hose, shower or sink faucet, sprinkler, hydrant, etc. because there are endless sources of water
  • Cons
    • Can only be used on polar substances, which are chemicals that have both positive and negative sides (created by unbalanced forces when atoms are bonded together)
    • Not useful for acids or bases – most of these are highly soluble in water, but it takes a tremendous amount of water to dilute an acid or base
    • All of the operations for water must be accounted for – might need to be isolated and disposed of, neutralized, filtered, or contained, which can be extremely time-consuming

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