Home → Blog → Resources → What Causes Bad Odors? The Science Behind Bad Smells – Polygiene
Odors are part of everyday life and, as one of the five senses, remain central to how we understand the world around us. Good smells can be incredibly stimulating, transporting you back in time to long-distant memories or getting you excited for an upcoming meal. But bad smells have just as pronounced an effect. Whether it’s musty towels and sweaty gym clothes or strong body odor, unpleasant smells can have a considerable impact on our self-confidence, comfort, and well-being.
In this article, we’ll explore what bad odors actually are, how they are created and detected, what causes bad odors, and what causes us to perceive certain smells as unpleasant. We’ll examine the chemistry behind bad odors, their environmental and biological sources, and the practical strategies you can use to counter them. We’ll also explore innovative odor-control technologies, including solutions developed by Polygiene, and answer some of the most frequently asked questions about body odor and smelly fabrics.
An odor is the interaction between gaseous chemical compounds in the air and the odor receptors in our nose. They occur when the volatile compounds suspended in the atmosphere enter the nose and bind to the specialized smell receptors in the olfactory epithelium. We have around 400 of these receptors, and molecules tend to trigger a range of these. Consequently, specific odors correlate with certain patterns of signals from our receptors.
The process of smelling an odor works in the following way:
We’ve explained what odors are, but what causes bad odors? To a certain degree, value judgements about odors are personal and cultural. People respond differently to odors, and what smells good to one person may be unpleasant for another. However, evolutionary biology also plays a role, and there are some bad smells that transcend personal and cultural distinctions and are almost universally disliked.
These bad smells are typically caused by the breakdown of organic matter. When bacteria, fungi, or other microorganisms digest proteins, fats, and similar compounds, they produce VOCs as byproducts. Our brains often interpret these as unpleasant smells.
Common compounds that cause by odors include include:
In many cases, bad smells are the result of microbes breaking down organic matter. However, it’s important to recognise that the microbes don’t smell themselves. Instead, it’s the byproducts they release as part of their metabolic process.
Many bad smells share common characteristics. They are often volatile molecular compounds capable of both easy evaporation and strong binding with our olfactory receptors. However, this is a purely chemical explanation. From an evolutionary standpoint, humans have evolved to identify and avoid sources of infection and decay. The brain links certain chemical signatures with potential danger and responds by triggering an unpleasant response. These dangers include things like waste, spoiled food, and disease.
In some instances, bad smells are a warning from our body to stay away from potentially harmful substances.
Environmental odors are those smells that originate in our external surroundings. We often distinguish them from personal body odors. Environmental bad odors can be caused by almost anything. However, some of the most common sources include:
Household odors
Mold and mildew
Mold also releases microbial VOCs that result in a damp, musty smell. You’ll often smell these odors wherever the conditions favour mold growth, such as in damp bathrooms, basements, and mattresses.
Industrial and urban odors
These odors often contain sulfur compounds, nitrogen oxides, and other pollutants.
Biological odors originate from living organisms and their metabolic processes.
Body odor
Sweat itself is mostly odorless. The bad smell is caused by bacteria on the skin breaking down sweat proteins and lipids. This occurs most frequently in the armpits, feet, and groin.
In the armpits and groin, apocrine glands produce sweat that is rich in proteins and lipids, which are ideal food sources for bacteria. The high concentration of sweat glands on the feet ensures there’s plenty of nutrition there, too. Cool, dark, and damp, all three spots are suited to bacterial growth and associated smells.
Decomposition
When organisms die, bacteria rapidly break down tissues, releasing putrescine, cadaverine, and sulfur-containing gases. This is why organic matter starts to smell pretty strongly when left in the bin or anywhere where airborne VOCs can reach our olfactory receptors.
Oral and digestive odors
Finally, bad breath (halitosis) is commonly caused by sulfur-producing bacteria in the mouth. Digestive processes can also produce gases that carry strong odors.
The most effective way to prevent and remove bad odors is to address the root cause, which is typically bacteria, mold and mildew, or decaying organic compounds.
You can achieve this by:
In some materials, particularly textiles, odors can linger after thorough cleaning. We’ve created several guides to help you eliminate smells in these cases.
Everyday clothing and workout gear, like gym tops, base layers, underwear, and leggings, are especially prone to odor retention. In many cases, this is because they are exposed to heavy sweating and are made from synthetic fibers that trap moisture and bacteria.
To remove bad odors from clothes, we recommend:
For more detailed advice on removing odors from textiles, check out our comprehensive guide to keeping clothes smelling fresh and our guide to removing sweat smells from clothes.
We’ve already explained what causes bad body odor, but how can you prevent it? Eliminating and reducing body odor requires you to minimize bacterial growth by preventing the build-up of nourishing sweat. To achieve this, you can:
If you want to know more, we have put together a dedicated guide to eliminating body odor.
Modern odor control technology encompasses a lot more than cleaning agents. Today, there’s an extraordinary range of advanced odor control solutions to explore.
In the house, HEPA air filters remove around 99% of dust, pollen, mold, and bacteria. Though they cannot remove existing VOCs and odors, they can help prevent odor-causing microbes. Activated charcoal absorbers are regularly used in enclosed spaces, such as closets and cupboards, while enzymatic cleaners can break down the compounds responsible for bad odors much more effectively than traditional agents.
However, the most significant improvements in odor control technology have come in the textiles sector. Here, Polygiene additive technologies are changing the way we think about odor protection, sustainability, and fabric design. In the context of odor control, Polygiene produces two main solutions.
Polygiene® StayFresh
Polygiene® StayFresh is designed to prevent the growth of odor-causing bacteria in textiles. The technology is based on silver chloride, a salt with antibacterial properties that has been used for centuries and occurs naturally in soil and water.
By inhibiting bacterial growth, StayFresh stops smells from forming and keeps clothing fresher for longer, even during warm weather or physical exertion. As it keeps odor in check, Polygiene StayFresh enables users to go longer without washing their clothes. This is highly practical when it comes to sportswear and outdoor apparel.
Arguably more importantly, it’s great for the planet, too. Less washing extends the lifespan of the clothing, preserves fabric performance, and reduces water and energy consumption. This means Polygiene-treated solutions last longer and are more sustainable.
Learn more about Polygiene StayFresh.
Polygiene® OdorCrunch2.0
Polygiene® OdorCrunch tackles environmental odors, such as cooking smells, smoke, and some body odors. Its unique silica-based formula captures and crunches the VOCs responsible for bad smells, such as sulfur and nitrogen, ensuring that they don’t cling to fabric fibers.
Similar to Polygiene StayFresh, Polygiene OdorCrunch2.0 keeps unwanted smells at bay, keeping clothes fresher for longer and reducing the need for washing.
Learn more about Polygiene OdorCrunch2.0.
Both Polygiene odor control solutions are integrated quickly and easily into textile products during the manufacturing process. They provide long-lasting, around-the-clock odor protection, and can be used individually or in combination. Polygiene provides assistance during initial integration and ongoing marketing support, ensuring our customers communicate the benefits of odor control in the most effective and impactful way.
What causes body odor?
Body odor is caused by bacteria breaking down sweat components, especially proteins and lipids. Sweat itself is largely odorless, and it’s the bacteria’s metabolic byproducts that cause most unpleasant smells.
What causes clothes to smell after washing?
Odor can persist if bacteria survive the wash cycle, if clothes aren’t dried properly, or if detergent buildup traps odor molecules. Again, bacteria are the primary cause of unpleasant odors in this situation, and prevention should focus on stopping bacterial growth and eliminating microorganisms from the fabric.
What bacteria cause body odor?
The main culprits are common skin bacteria, such as species from the genera Corynebacterium, Staphylococcus, and Cutibacterium, which break down sweat into odor-producing compounds.
What’s the most effective way to prevent odors?
Thorough washing and air-drying will usually eliminate most bacteria, and Polygiene Freshness technologies will stop them from returning, preventing smells in textiles and allowing you to wash products less frequently. This ensures you can wear and use your textiles for longer without worrying about odors.
Polygiene technology is used in almost every textile sector, from leisurewear and uniforms to bedding and pet products. If you’re interested in learning more about our Freshness solutions, head to our dedicated solutions page or reach out to our expert team today.
