The 4 Principles of Odor Control

Odor control in the cleaning and restoration industry involves much more than covering an unpleasant smell with fragrance.

Malodors are often caused by residues, contamination, smoke, biological materials, moisture-related conditions, or other substances that remain in the environment. Successfully addressing them requires technicians to determine where the odor is coming from, how it traveled, and what materials have been affected.

The ANSI/IICRC S100 Standard for Professional Cleaning of Textile Floor Coverings describes four deodorizing principles:

"There are four deodorizing principles: remove the source (as practical); clean off significant residue, recreate the conditions of penetration using an appropriate odor counteractant, and seal as necessary."

These principles provide technicians with a logical process for approaching odor-control projects. Rather than immediately reaching for a deodorizer, the technician works through the problem step by step.

Principle #1: Remove the Source

Effective odor control begins with one question:

Where is the odor coming from?

Whenever practical, the material producing the odor should be located and removed.

Examples might include urine-contaminated carpet or padding, smoke-damaged materials after a fire, spoiled organic material, or other odor-producing contamination.

Simply treating the air while leaving the source in place may provide temporary improvement, but the odor can return because the material responsible for producing it is still present.

This is why inspection is such an important part of professional odor control.

Odor sources are not always visible. Contamination may be located:

• beneath carpet or flooring
• behind walls or other building materials
• inside wall or ceiling cavities
• within upholstered furniture
• inside HVAC components or ductwork
• on structural materials
• within porous contents

Technicians should carefully evaluate the affected environment before deciding on a treatment method.

Removing as much of the odor source as practical gives the remaining deodorization steps a much better chance of succeeding.

Principle #2: Clean Contaminated Surfaces

Removing the original source does not necessarily remove everything responsible for the odor.

Residues may remain on surrounding surfaces, textiles, contents, or structural materials. These residues should be cleaned or, when appropriate, the affected material may need to be removed.

Professional cleaning agents can help loosen, dissolve, emulsify, or suspend soils so they can be physically removed from the surface.

This distinction is important.

The goal is not simply to make the contaminated area smell better. The goal is to remove as much odor-producing residue as practical.

Depending on the situation, cleaning may involve several steps, such as:

• dry soil or particulate removal
• extraction
• surface cleaning
• washing
• agitation
• rinsing
• controlled application of appropriate cleaning agents

The cleaning method should always be selected based on the material being treated, the type of contamination, and applicable industry standards and manufacturer recommendations.

Some cleaning products may also contain odor-counteracting ingredients, but deodorization should not replace proper cleaning.

If odor-producing compounds have penetrated deeply into porous materials and cannot be adequately removed, additional treatment may be necessary.

Principle #3: Recreate the Conditions of Penetration

This is one of the most important and sometimes misunderstood principles of professional odor control.

To effectively treat an odor, technicians should consider how the odor originally reached the affected material.

Was the contamination:

• deposited as a liquid?
• carried through the air as smoke?
• absorbed into a porous material?
• distributed throughout a room or structure as vapor or airborne contamination?

The deodorization method should be capable of reaching the affected areas in a similar way.

For example, if smoke traveled throughout a structure and penetrated porous materials, treating only easily accessible surfaces may not address all of the affected areas.

Depending on the conditions, technicians may use appropriately selected odor counteractants in liquid, vapor, or other forms to reach the areas where odor-producing compounds remain.

The objective is not simply to add a stronger or more pleasant smell.

Professional deodorization is intended to treat the remaining odor at the places where it exists.

Product selection and application methods should always be appropriate for the contamination, building materials, occupants, and conditions of the project.

Principle #4: Seal as Necessary

Sometimes odor remains even after the source has been removed, affected materials have been cleaned, and appropriate deodorization treatments have been performed.

This can occur when odor-producing residues have penetrated deeply into porous structural materials and cannot reasonably be removed.

In these situations, sealing may be considered.

Restoration-grade sealers or encapsulating coatings can help isolate remaining residues within a material and reduce their ability to release odor back into the occupied environment.

Sealing should generally be considered after appropriate source removal and cleaning—not as a substitute for them.

Before applying a sealer, surfaces should typically be:

• properly cleaned
• free of loose contamination
• adequately dried
• prepared according to the coating manufacturer's instructions

There are different types of sealers available, and the appropriate product will depend on the material, contamination, environmental conditions, and intended finish.

Technicians should always follow product-label instructions regarding application, ventilation, drying, recoating, and compatibility with subsequent finishes.

Why All Four Principles Matter

Professional odor control works best when technicians treat the cause of the odor rather than focusing only on the smell itself.

Skipping one of the early steps can make the entire process less effective.

For example, applying deodorizer without removing the source may only provide temporary relief. Sealing a contaminated surface without properly cleaning it may leave unnecessary contamination behind.

A more systematic approach looks like this:

Remove the source → Clean the residue → Treat remaining odor where it penetrated → Seal when necessary

Each step builds on the one before it.

Odor Control Requires Investigation, Not Just Deodorizer

Odor-control projects can vary considerably.

Smoke damage, pet urine, biological contamination, microbial-related odors, sewage, and other sources behave differently and may require different treatment methods.

That is why professional odor control begins with understanding the source, the affected materials, and the way contamination moved through the environment.

Technicians who understand these principles can make better decisions about inspection, cleaning, deodorization, and restoration rather than relying on fragrance or a single treatment method.

Conclusion

Effective odor control is a process.

The four deodorizing principles described in the ANSI/IICRC S100 Standard provide restoration and cleaning professionals with a practical framework:

1. Remove the source as practical.
2. Clean significant residue from affected materials.
3. Recreate the conditions of penetration using an appropriate odor counteractant.
4. Seal affected materials when necessary.

Following these principles helps technicians address the underlying cause of a malodor rather than simply covering it temporarily.

For cleaning and restoration professionals, understanding why an odor exists and how it traveled is just as important as knowing which product to use.

Want to Learn More About Professional Odor Control?

Restoration Certified offers live online IICRC Odor Control Technician (OCT) training for cleaning and restoration professionals who want to strengthen their understanding of odor sources, deodorization methods, equipment, chemistry, and professional odor-control procedures.