Decontamination — the removal of hazardous substances from people, clothing, and surfaces — is one of the most consequential actions you can take after exposure to a chemical, biological, or radiological (CBR) hazard. Studies show that removing outer clothing alone eliminates up to 80% of surface contamination. Rinsing with water for 15–20 minutes removes a further 90%+ of residual contamination. Speed is critical: every minute that a chemical agent remains on skin is additional damage occurring. For radiological contamination, prompt decontamination before particles are ingested or inhaled makes a dramatic difference to long-term dose.
The Core Principle: Remove, Rinse, Relocate
All decontamination — whether performed by trained HAZMAT teams or improvised by individuals — follows the same fundamental sequence:
- Remove — Strip off outer clothing and any visible contamination source
- Rinse — Flush with copious clean water
- Relocate — Move to a clean area away from the contamination zone
Even without specialist equipment, these three steps performed quickly and correctly will dramatically reduce your total exposure and long-term health impact.
General Principles Applicable to All CBRN Hazards
Protecting the Rescuer
Before assisting a contaminated person, assess whether you have adequate protection. Without appropriate personal protective equipment (PPE):
- Do not enter a known contamination zone.
- Keep to an upwind, uphill position.
- Use the longest possible distance when assisting.
- Use gloves if available — even disposable kitchen gloves — when handling contaminated clothing.
- If you must approach without PPE, minimise your time in contact, cover your mouth and nose, and decontaminate yourself afterwards.
Undressing Technique
The way clothing is removed matters significantly:
- Cut clothing where possible — cutting removes it without pulling it over the face and hair, which spreads contamination.
- If cutting is not possible, roll clothing outward and downward from the collar — like peeling off a jumper — to keep contamination away from the face.
- Remove shoes and socks by pulling them away from the body.
- Remove jewellery — rings, watches, and necklaces can trap contamination against skin.
- Place all removed items in a plastic bag. Seal the bag. Label it if possible.
- Move the bag away from the clean area.
⚠️ Do not carry contaminated clothing bags into vehicles or clean buildings. Set them aside at the decontamination site for disposal by trained responders.
Chemical Decontamination
Liquid/Vapour Chemical Agents
Time is tissue. Nerve agents and blister agents continue to cause damage as long as they are in contact with skin.
Immediate steps:
- Leave the area — move upwind and uphill from the source.
- Remove all clothing using the cutting or rolling technique described above. This step alone removes approximately 80% of liquid contamination.
- Flush eyes — if eye contact occurred, immediately flush with copious clean water for a minimum of 15–20 minutes. Tilt the head so water flows away from the unaffected eye. Remove contact lenses before or during rinsing if possible.
- Flush all exposed skin — use a running water source. Begin at the head and work downward. Do not scrub — use gentle water pressure or blotting. Scrubbing can open pores, embed particles, or spread contamination.
- Rinse the mouth — spit, do not swallow. Do not induce vomiting unless directed by poison control.
- Blow the nose and wipe mucous membranes gently with a clean damp cloth.
- Do not use bleach on skin — concentrated bleach causes additional tissue damage. Plain water is correct for skin.
- Seek medical attention even if symptoms appear mild — many chemical agents have delayed effects.
Improvised Chemical Decontamination
When no running water is available:
- Use any available liquid: bottled water, sports drinks, even milk — the dilution effect is the primary mechanism, not the specific fluid.
- A garden hose from a neighbour's tap is an excellent improvised decontamination shower.
- Fire service hydrants may be used by first responders.
- Natural water sources (stream, lake) can be used if no alternative exists — contamination from an unknown source is generally less harmful than continued skin contact with a known chemical agent.
Improvised barrier:
- Before water rinse, dry decontamination using flour, baking soda, or dry dirt applied and then brushed off can physically remove some liquid contaminants (particularly for skin not immediately near water).
- This is a secondary option — do not delay water rinsing for dry decontamination.
| Chemical Agent Type | Primary Decontaminant | Notes |
|---|
| Nerve agents (liquid) | Water flush | Remove clothing first; speed critical |
| Blister agents (mustard) | Water flush | Delay = more damage; thorough rinsing |
| Blister agents (lewisite) | Water; RSDL if available | Faster acting than mustard |
| Cyanide (liquid) | Water flush | Primarily an inhalation hazard |
| Irritants (CS, pepper spray) | Water; soap and water | Do not rub eyes — irrigation only |
| Unknown liquid chemical | Remove clothing, water flush | Assume worst case |
Biological Decontamination
Biological contamination decontamination is somewhat different because the contaminant is a living organism (bacteria, virus, spores) rather than a reactive chemical.
When Is Biological Decontamination Indicated?
- Following a suspected deliberate biological release (aerosol, powder, or liquid)
- After known or suspected exposure to a patient with a highly infectious disease requiring enhanced precautions (e.g., viral haemorrhagic fever)
- After exposure to suspicious powders or materials in the mail/packages
Procedure
- Remove outer clothing using the same technique as for chemical agents. Seal in a bag.
- Shower with soap and water. Soap is more effective than plain water for biological agents — the surfactant action disrupts cell membranes and washes organisms from skin.
- Duration: 5–10 minutes of thorough soaping and rinsing is appropriate (longer than for plain water rinse).
- Shampoo hair. Do not use conditioner — it binds particles to hair shafts.
- Blow nose and rinse mouth with water.
- Dispose of water — shower runoff should ideally drain to the sewage system, not outdoor ground.
What Biological Decontamination Does Not Do
- It does not treat infection already established in the body.
- If you have inhaled biological agents, skin decontamination does not reverse that exposure.
- After decontamination, follow public health guidance on prophylactic antibiotics, vaccines, or monitoring as appropriate to the specific agent.
⚠️ Anthrax spores (Bacillus anthracis) are particularly resistant. If anthrax exposure is suspected, clothing should be bagged and not handled further until collected by authorities. Thorough showering with soap and water is appropriate for skin.
Radiological Decontamination
Radiological decontamination removes radioactive particles from the surface of the body. It does not reverse radiation dose already absorbed — it prevents additional dose from continued contact with contaminating particles, and critically, prevents ingestion or inhalation of particles.
Signs You May Need Radiological Decontamination
- You were outdoors during or after a nuclear detonation or dirty bomb explosion
- You were in a building where a radioactive dispersal device was detonated
- You were near an industrial radiological incident
- Emergency services have identified the area you were in as contaminated
- A radiation meter shows elevated readings from your clothing or skin
Procedure
- Remove all outer clothing. This single step removes approximately 80% of radiological surface contamination. Bag and seal all removed clothing.
- Remove shoes. Shoes accumulate particles from ground contact.
- Blow nose — radioactive particles may have been inhaled and caught in nasal mucus.
- Gently wipe face with a clean, damp cloth, paying attention to eyelids, eyebrows, and areas where dust settles.
- Shower with lukewarm water and mild soap. Avoid hot water (dilates pores) and vigorous scrubbing (micro-abrasions in skin can uptake particles).
- Shampoo hair using mild shampoo. Rinse thoroughly. Repeat if possible.
- Do NOT use conditioner — it bonds to hair and will trap radioactive particles.
- Clean under fingernails with a nail brush if available.
- Change into fresh, clean clothes — ideally from sealed packaging or a drawer that was not exposed.
- If available, a radiation survey meter can confirm decontamination success.
Wound Decontamination (Radiological)
If contamination entered a wound:
- Irrigate gently with sterile water or saline.
- Cover with a sterile dressing.
- Seek immediate medical care — internal contamination in wounds requires specialist assessment.
⚠️ Swallowing, inhaling, or absorbing radioactive particles through wounds ("internal contamination") is far more serious than surface contamination. Internal emitters deliver ongoing radiation dose to surrounding tissues and organs. Preventing it through prompt surface decontamination is critical.
Mass Casualty Decontamination at a Scene
When emergency services establish a formal decontamination corridor:
The "Ladder System" Layout
Professional mass decontamination typically involves:
- Casualty Clearing Station — initial triage, remove from hot zone
- Dry decontamination — remove clothing
- Wet decontamination — water showers (warm if possible, cold if not)
- Secondary dry — towel off with clean materials
- Re-dressing — clean coveralls or blankets
- Secondary medical triage
- Follow directions from emergency responders without hesitation.
- Remove clothing as directed — responders will provide privacy screens or at minimum instruct on technique.
- Move through the shower line at the pace directed — do not rush and do not linger.
- Accept the replacement clothing provided, regardless of quality.
- Do not re-enter the contaminated zone to retrieve belongings.
Post-Decontamination
After completing decontamination:
- Report to medical triage for assessment of symptoms.
- Provide details of your estimated exposure: what you were exposed to (if known), duration, route (skin, inhalation, ingestion).
- Retain your sealed clothing bags for forensic and dosimetry purposes — do not discard them.
- Do not eat, drink, or smoke until cleared by medical personnel.
- Monitor for delayed symptoms in the hours and days following exposure.
Quick Reference
| Contaminant Type | Primary Action | Secondary Action | Do Not |
|---|
| Liquid chemical | Remove clothes, flush water 15–20 min | Seek medical care | Use bleach on skin |
| Blister agent | Remove clothes, water flush immediately | Medical care, sterile dressings on blisters | Pop blisters, delay water |
| Biological powder | Remove clothes, shower with soap | Follow public health guidance | Re-enter area |
| Radiological particles | Remove clothes, shower (no conditioner) | Clean nails, blow nose, change clothes | Use conditioner, scrub hard |
| Unknown CBRN | Remove clothes, water flush | Seek emergency medical care | Re-enter zone |
This article provides general decontamination guidance for preparedness purposes. Formal HAZMAT or CBRN decontamination should be performed or overseen by trained emergency responders whenever possible. Always follow the specific instructions of emergency services on scene.