Quick answer
Thermal fogging is a smoke odor treatment in which a machine heats a deodorizing solvent into a fine fog, with particles close in size to smoke, so that the product reaches the cracks, crevices and pores where smoke settled, and it is used as one late step after cleaning, not as a stand-alone fix.
Trade sources describe it as only one step in a larger process. People and pets leave during treatment, technicians wear respirators, and the building is ventilated before anyone returns.
Quick facts
The key facts about Thermal Fogging, with sources:
- What it is
- A machine heats a deodorizing solvent into a fine fog to reach the places smoke settled 1
- Who must leave
- All people and pets leave the treated area 1
- Worker protection
- Respirators, eye protection and skin protection for technicians 1
- Notice
- Notify the local fire department and post a notice with the time occupants can return 1
- Regulator view
- EPA advises avoiding products that add chemicals to the air to neutralize smoke odor, naming ozone and hydroxyl generators 3
- Standard behind the trade
- ANSI/IICRC S700 (first edition, 2025) covers fire odor management in general terms 9
Key takeaways
- Thermal fogging treats smoke odor with a heated solvent fog. It is a finishing step after residue is cleaned and removed, not a replacement for cleaning 12.
- People and pets leave the area during treatment, and technicians wear respirators and other protection 1.
- The fire department should be told first, because the fog can look like smoke to neighbors 1.
- A strong smell after fogging is not a clearance of the building. Odor control does not establish that surfaces or air are safe 5.
- The product label, the safety data sheet and the machine manual set the real rules for a job. A reader’s guide cannot replace them.
What thermal fogging is
A thermal fogger is a machine that heats a liquid until it becomes a visible fog. In smoke odor work, the liquid is a deodorizing product the trade calls an odor counteractant 1.
A trade article by a restoration training instructor explains the logic. The fog’s particles are very small, close to the size of smoke particles, so they can reach tiny cracks, crevices and pores where the original smoke deposits settled 1.
A second trade article describes the idea as recreating fire conditions. It says the method relies on two effects. Agglomeration makes particles heavier so they settle on surfaces where they can be cleaned.
Adsorption is the chemical attraction of smoke odor molecules to the deodorant molecules 2. Both articles come from the cleaning trade press, so they describe how practitioners explain the method. They are not independent test results.
Fogging is therefore a delivery method. It is a way of getting a product into places a sprayer cannot reach. What the product does depends on the product, and that is why the label and the safety data sheet matter more than the machine.
The same trade sources say fogging is one step in a larger process: suppression spraying with a pressurized sprayer, plus removal of as much of the odor source as possible by vacuuming and hand-cleaning 1.
In one description of professional work, the solvent-based counteractant applied with a thermal fogger comes last, once no smoke odor is detectable 2.
The smoke odor removal entry explains the whole sequence, and the fire and smoke damage restoration page shows how odor work fits into a fire job.
How a fogging treatment is run
The steps below summarize one instructor’s published procedure for professional crews 1. They are given so owners can recognize a careful job. This is not a how-to, and a product’s own label and manual override any article.
- Prepare the building. Make sure all people and pets have left. Close exterior doors and windows. Open cabinets, closets and drawers, staggering drawers so the bottom one opens farthest 1.
- Notify and post. Tell the local fire department. Post notices that fogging is underway, with a time when occupants can return, because passersby may mistake the fog for smoke 1.
- Remove ignition and alarm risks. Shut off open flames, including pilot lights. Cover or disable smoke detectors. Cover fish tanks and food containers 1.
- Protect the crew. Technicians wear respirators, eye protection and skin protection 1.
- Work in a set order. Teams of two fog the open drawers, closets and cabinets first, then start in the farthest corner and move back toward the exit, room by room 1.
- Let it work, then ventilate. The article describes leaving the area undisturbed for 30 to 60 minutes and then ventilating for at least 30 minutes. That is one instructor’s practice, not a clearance standard, and product directions may differ 1.
- Handle sensitive people with care. The article says people with respiratory or other sensitivities should ask a healthcare professional whether extra ventilation is advisable 1.
- ClearanceFire department says the building is safe
- Remove sourceSoot, debris and burned material out
- Clean and sprayVacuum, hand-clean, suppression spray
- Check odorIs smoke odor still detectable?
- Fog if plannedPeople and pets out; crew protected
- VentilateBefore anyone returns, per the plan and label
The sequence follows two trade articles by restoration training instructors. They describe practice. They are not a standard. Source: [1] [2]
The preparation list is long because the treatment puts a chemical fog through every room. The re-entry decision belongs to the contractor’s written plan and the product label, not to a rule of thumb.
Kinds of odor treatment and where fogging differs
| Treatment | How it works, in the sources’ words | Occupancy or safety note | Source |
|---|---|---|---|
| Thermal fogging | Heated solvent fog with smoke-sized particles reaches pores and crevices | People and pets leave; crew wears respirators | 1 |
| Surface counteractant spray | Water-based product sprayed on floors to keep odorous gases from becoming airborne | Used earlier in the sequence | 2 |
| Hydroxyl generator | Produces oxidizing gases that break apart odor molecules | EPA advises avoiding; see the hydroxyl entry | 83 |
| Ozone generator | Produces ozone gas | Lung irritant; no federal approval for occupied spaces | 4 |
| Cleaning and removal | Takes out the residue and materials that hold odor | Needs soot and PPE precautions | 56 |
| Masking sprays | Cover the smell | FEMA says not effective at eliminating odor | 5 |
Fogging
Example: reading a fogging line on an estimate
The thermal fogging estimate below is an illustration of how to test an estimate, not a real quote. Imagine a fire estimate with a line that says “thermal fog — whole house.” The questions in the middle column follow the trade procedure described above 12.
| Estimate detail (example) | Question to ask | Why it matters |
|---|---|---|
| “Thermal fog — whole house” | What cleaning and removal come before it? | The trade sequence puts fogging after source removal and cleaning 2 |
| No line for HVAC or cavities | How are ducts and wall cavities handled? | FEMA recommends professional duct and furnace cleaning after smoke 5 |
| “Product: proprietary deodorizer” | Which product, and may I see the label and safety data sheet? | The label and SDS set precautions and re-entry; articles cannot |
| “Occupants may remain” | Why, and under which label statement? | The trade procedure says all people and pets leave the area 1 |
| No notice mentioned | Will the fire department be told? | The trade procedure says to notify it and post notices 1 |
| “Odor guaranteed gone” | What exactly is guaranteed, and for how long? | No public standard defines an odor-free result |
- If Fogging follows documented cleaning and removal
- Then Reasonable sequence; confirm the product and the occupancy plan
- If Fogging is the whole odor plan
- Then Ask what is being removed; the trade sequence treats fogging as a late step 2
- If The plan has you stay in the building
- Then Ask for the label statement that allows it; the trade procedure has people and pets leave 1
A good answer to each question is specific and written. A vague answer is a reason to compare quotes. The estimate review tool and the hiring guide help with that comparison.
Where thermal fogging shows up
On a fire estimate. It appears as “thermal fog,” “deodorization” or “odor control,” which may be priced as a service or a machine rental. The word alone tells you little. Ask what comes before it.
In the work authorization. A good authorization names the treatment and the access rules: who leaves, for how long and who tells the fire department.
In the claim file. Adjusters may ask for the product and the reason for the treatment. Policies vary on how odor work is covered, so read your wording, and see the insurance claims guide.
In contents and structure scopes. Fogging touches both. Contents cleaning is a separate scope; see the contents restoration page.
Before a rebuild. Odor treatment normally finishes before new finishes go in. The how restoration works guide shows the order of trades.
What fogging is said to do well
- It reaches small spaces. The trade description says the fog is close in size to smoke particles and can reach cracks, crevices and pores 1.
- It can treat many surfaces in one pass, including areas where drawers and cabinets are opened first 1.
- It fits the end of a sequence. After soot and debris are gone and the smell is faint, a fog can address what remains 2.
- It does not need to be wiped on every surface by hand, which may reduce hand labor in hard-to-reach places. Treat this as a trade claim, not a tested result.
Where thermal fogging falls short
- It does not remove the source. The instructor’s article says fogging alone does not remove the odor source, so it must be combined with vacuuming and cleaning 1.
- Some odors need other methods. The same article says tobacco odors may need different procedures and specially formulated products 1.
- It is not a safety clearance. FEMA says its cleanup approaches can reduce but not eliminate contaminants, and recommends environmental testing after cleanup before long-term occupancy 5. A treated smell tells you nothing about soot toxicity.
- Regulators lean away from added chemicals. EPA’s ash fact sheet advises avoiding products that add chemicals to the air to remove or neutralize smoke odors, naming ozone and hydroxyl generators and other oxidizers 3. It does not name thermal foggers, so this page does not claim it covers them. It does show the cautious stance.
- Evidence is mostly trade-reported. The sources loaded for this page are trade articles and a university extension guide. No independent study or manufacturer safety data sheet was loaded, so this page does not rate effectiveness.
What drives the cost of a fogging service
The thermal fogging page gives no prices. Fogging may sit inside a larger fire scope, and costs vary by region and contractor, so no figure here would meet our cost standard.
The cost drivers are the size of the treated area, the number of passes, the product used, crew size and the time needed to prepare and ventilate. The trade procedure works in teams of two and covers every room and every cabinet, so preparation is a real share of the labor 1.
The real cost question is what else is on the estimate. If fogging is paid for in place of cleaning and removal, the odor may return. Compare line items, not totals.
There is no lifespan or warranty on a fog as such. Ask for any guarantee in writing, with its limits, and see the cost guide.
Who does what, and what needs notice
| Party | Role | Source |
|---|---|---|
| Restoration contractor | Plans the sequence, chooses the product, runs the machine, ventilates | 12 |
| Technicians | Wear respirators, eye and skin protection | 1 |
| Owner and occupants | Leave the area with pets; return only when the plan and label say it is safe | 1 |
| Local fire department | Notified before fogging; sets building entry rules after the fire | 17 |
| Insurer | Reviews odor scope and charges under policy terms | Policy wording varies |
- The fire department has cleared the building for work
- Soot and debris are removed first
- The contractor has shown the product label and safety data sheet
- People, pets and food containers are out or covered as the plan says
- The fire department is told and a notice is posted
- Re-entry follows the written plan, not a guess
After the fog: ventilation and follow-up
Ventilation comes first. The trade procedure calls for ventilating after the fog has been allowed to work 1. Follow the contractor’s written re-entry plan and the product label. If you notice irritation, leave and tell the contractor.
Keep air moving and filtered. FEMA suggests a filter rated MERV 11 or higher in constant fan mode once the bulk of soot is gone, and activated charcoal for light odor 5.
Check the smell over several days and in different weather. If it returns, ask the contractor what source remains. A returning smell can mean a source was not removed, which is why the sequence starts with removal.
Keep the product name, label and safety data sheet in your claim file. They matter if anyone in the home reports a reaction.
Warning signs, and when to stop
- A plan that has you stay home during fogging, with no label statement to support it.
- No product name, label or safety data sheet on request.
- Fogging proposed in place of cleaning, removal or duct work.
- No fire department notice, which the trade procedure treats as standard 1.
- Irritation of the eyes, nose, throat or lungs after treatment. Leave and ventilate, and ask a health professional if symptoms continue.
- A household member with asthma, heart or lung disease, or chemical sensitivity, who should not be present and who should ask a health professional about return.
Safety and risk
Do not run a thermal fogger or deodorizing fog yourself, and do not stay in or enter a building during treatment. The trade procedure has all people and pets leave, technicians wear respirators and the fire department be told 1.
Do not enter a fire-damaged building before it is cleared 7. Fogging does not show that a building is free of soot or toxic residue 5. Follow the product label and safety data sheet over any article.
Standards, guidance and rules
Industry standard. ANSI/IICRC S700 covers fire and smoke damage restoration, including restoration cleaning and fire odor management. The first edition is dated 2025, and a new consensus body is revising it 9.
The IICRC does not publicly detail fogging, and the standard is paid, so this page does not describe its text. A standard is voluntary unless a contract or law adopts it.
Product law and labels. Chemical products carry labels and safety data sheets that set use, protection and re-entry conditions. Those documents govern a job. This page did not load a specific product’s label or sheet, so it states no product-specific rules.
Government guidance. EPA’s ash fact sheet advises avoiding products that add chemicals to the air to remove smoke odors and names ozone and hydroxyl generators and other oxidizers 3. It does not mention thermal fogging.
Worker safety. Respirator and chemical handling for employees fall under OSHA rules, which this page does not summarize.
Local rules. Fire departments and building departments set re-entry and notice rules. Insurance policies set their own terms.
Thermal fogging compared with related terms
| Term | What it is | Read more |
|---|---|---|
| Thermal fogging | Heated solvent fog delivered to small spaces | This page |
| Hydroxyl generators | Devices that produce oxidizing gases | Hydroxyl generators |
| Ozone treatment | Ozone gas used in unoccupied spaces | Ozone treatment |
| Soot removal | Cleaning the physical residue | Soot removal |
| Protein residue | Kitchen fire residue that can hide odor | Protein smoke residue |
Common myths about fogging
- Myth A fogger removes smoke odor by itself.
- Reality The trade instructor’s article says fogging alone does not remove the source and must be combined with vacuuming and cleaning 1.
- Myth Fogging is safe to sit through.
- Reality The trade procedure has all people and pets leave and technicians wear respirators 1.
- Myth Once the smell is gone, the house is safe.
- Reality FEMA says cleanup can reduce but not eliminate contaminants and recommends environmental testing before long-term occupancy 5.
- Myth Fog on a lingering odor fixes soot.
- Reality Soot is a physical residue to be cleaned first; UF/IFAS says soot must be removed before deodorizing textiles 6.
- Myth It works the same on every smell.
- Reality The trade article says tobacco odors may need different procedures and products 1.
Where local rules change the picture
No state variable changes the physics of fogging, so this page names none. The rules that do vary are local: fire departments decide when a building can be entered, may expect notice before fogging and may restrict open flames and alarms.
The trade procedure names notifying the local fire department, and your own fire department can tell you what it expects 17. Insurance rules for odor claims also differ by state. Ask your insurer and the fire department before work starts.
When this matters to you, and what to do next
Fogging matters when a contractor proposes it. Your job is to check the sequence: cleaning and removal first, then the product, then the occupancy plan. If any of those is missing, slow down.
Ask for the product label and safety data sheet, and ask who leaves, for how long and who tells the fire department. The scam avoidance guide flags promises that cannot be measured.
If someone in the home has respiratory disease or sensitivities, talk to a health professional and ask the contractor for a non-fog plan. FEMA’s ladder of cleaning, filtering and absorbing is a cautious baseline 5.
Decision rule
Fogging after cleaning is a reasonable question to ask about. Fogging instead of cleaning is a reason to get a second quote.
Questions about Thermal Fogging
What is thermal fogging?
It is a smoke odor treatment in which a machine heats a deodorizing solvent into a fine fog, so the product reaches the cracks, crevices and pores where smoke settled. A trade article describes it as one step in a larger process that includes cleaning and removing the odor source 1.
Does thermal fogging remove smoke smell?
It can reduce it as part of a sequence, but trade sources say fogging alone does not remove the odor source and must be combined with vacuuming and hand-cleaning 1. One description of professional practice puts it last, after smoke odor is no longer detectable 2.
Is thermal fogging safe for people and pets?
Not during treatment. The trade procedure has all people and pets leave the area, technicians wear respirators and the area be ventilated afterward 1. The product’s label and safety data sheet set the exact conditions, so ask the contractor to show them.
How long do I stay out after fogging?
It depends on the product, the label and the written plan. One trade article describes leaving the fog undisturbed for 30 to 60 minutes and then ventilating for at least 30 minutes 1. That is one instructor’s practice, not a standard, so follow the label and contractor plan.
Why does the fire department need to be told?
The fog can look like smoke. A trade article advises notifying the local fire department and posting notices with a return time, because neighbors may see fog leaving the building and call it in 1. Your local department may have its own expectations.
Can I rent a thermal fogger and do it myself?
This page does not recommend that. The trade procedure involves respirators, covering alarms, shutting off pilot lights and clearing the building 1, and the product has its own label and hazards. Smoke odor work is better left to trained crews working to a written plan.
How is thermal fogging different from ozone or hydroxyl treatment?
Fogging delivers a heated solvent product as a fog, while ozone and hydroxyl generators produce oxidizing gases. EPA says ozone can damage the lungs and has not been approved by any federal agency for occupied spaces 4. See the ozone and hydroxyl entries for details.
Does fogging replace soot cleaning?
No. Soot is a physical residue that has to be cleaned. UF/IFAS says soot must be removed before textiles are cleaned or deodorized 6, and the trade sequence has fogging after cleaning 2. Fogging a sooty house may cover the smell without removing the cause.
Will thermal fogging make my home safe to live in?
Fogging addresses odor, not safety. FEMA says cleanup can reduce but not eliminate contaminants from smoke and recommends environmental testing after cleanup before long-term occupancy 5. Ask your contractor and, where needed, a qualified environmental professional what the treatment does and does not show.
What should I ask a contractor who proposes thermal fogging?
Ask what will be cleaned and removed first, which product will be used, to see its label and safety data sheet, who must leave and for how long, whether the fire department will be told and what happens if the odor returns. Get the answers in the written scope.
Sources
- Cleanfax (ISSA), Effective Thermal Fogging (November 6, 2014), by a restoration technical training instructor, retrieved .
- Cleanfax (ISSA), After the Fire (July 20, 2015), retrieved .
- U.S. EPA, Protect Yourself from Ash (fact sheet EPA-452/F-26-011), retrieved .
- U.S. EPA, Ozone Generators That Are Sold as Air Cleaners, retrieved .
- FEMA, Marshall Fire Mitigation Assessment Team: Homeowner’s Guide to Risk Reduction and Remediation of Residential Smoke Damage (revised April 2025), retrieved .
- UF/IFAS Extension, Handling Smoke Damage after a Fire: Getting Soot and Smoke Out (publication DH 1317), retrieved .
- U.S. Fire Administration, After the Fire Strikes: More Information (archived page), retrieved .
- Restoration Industry Association, Are Hydroxyl Generators Safe for Odor Removal?, retrieved .
- IICRC, ANSI/IICRC S700 Standard for Professional Fire and Smoke Damage Restoration (edition and scope), retrieved .
Expert review
Written by the HyreRestore Research Desk. Not yet reviewed by an outside expert. We say so rather than imply a review that has not happened; see our editorial policy.
How the numbers were checked: Two Cleanfax trade articles by restoration training instructors supplied the description of how thermal fogging works, where it sits in a job and the preparation and safety steps.
They describe practice and are not independent tests. EPA’s ash and ozone pages, FEMA’s smoke damage guide and a UF/IFAS extension publication supplied the regulator and government context.
The IICRC page supplied the S700 scope; the standard is paid and was not reproduced.
No manufacturer safety data sheet or product label was loaded, so no product-specific rule, re-entry time or hazard is stated beyond what the trade articles say, and the page tells readers the label governs.
The estimate lines in the worked example are an illustration. No dollar figures are given. The page is held for review by a qualified fire and smoke restoration professional.
Suggest a correction. We fix errors and say what changed.