How to Prevent the "Damp Smell" That Lingers on Summer Evenings: The Cause May Be Your Clothes Rather Than Body Odor

When the hot and humid season arrives, you may notice a smell similar to damp laundry while at the supermarket or on the train after work. It is that distinct odor that drifts from people who have been sweating, regardless of their age or gender. Since it is easy to imagine that the person has been working all day, I think to myself, "Thank you for your hard work." However, the desire to show appreciation and whether or not one finds that smell pleasant are two different things.

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1. An odor that comes from clothes rather than body odor

This smell is easily mistaken for body odor, but in reality, it is often caused by undershirts or shirts dampened by sweat rather than the skin itself. Clothes that smelled like almost nothing when you put them on in the morning can start to emit a damp smell as they absorb sweat in the afternoon. Even if they seem odorless after washing, sebum or bacteria-derived substances remaining inside the fibers begin to smell again due to body heat and moisture.

Therefore, if you think this problem can be solved simply by washing your body thoroughly, you might miss the mark. Even for people who skip bathing, if their clothes are clean, they may not smell enough to be noticeable. While keeping the skin clean is certainly necessary, managing your clothes is just as important, if not more so.

2. The bacteria that create the odor

Sweat itself does not have a strong smell. The cause of the odor is bacteria that multiply by feeding on sweat and sebum.

For the damp smell of clothing, Moraxella bacteria are well-known, and it is understood that they use sebum stains that were not completely removed during washing to create the substances that cause the damp smell.

On the other hand, on the skin, Staphylococcus, Corynebacterium, and Micrococcus break down sweat and sebum, each producing different types of odors.

In other words, the unique smell felt in summer is caused by several types of bacteria. It is not uncommon for body odor caused by skin bacteria to overlap with the damp smell created by bacteria remaining in clothes dampened by sweat.

3. Quick-drying properties and odor resistance are not the same

As summer undershirts, products with high quick-drying properties using synthetic fibers such as polyester are widely available. They are functionally excellent because they dry easily even after absorbing sweat and do not feel sticky. However, this does not mean that odors are less likely to remain.

Synthetic fibers, especially polyester, tend to retain oily stains like sebum, even though they do not hold moisture well. Even if the moisture from sweat dries quickly, sebum and odor-causing substances accumulate in the fibers, and past odors can reappear after sweating just a little. Even if they are comfortable when new, after wearing them for a few months, they become undershirts that smell shortly after being worn, even if they were odorless right after washing.

In my experience, I feel that synthetic fiber undershirts are more prone to a damp-like smell than cotton undershirts. While cotton has the disadvantage of being slow to dry because it absorbs a lot of sweat, it is easier to remove sebum stains through normal washing, and odors are less likely to accumulate over a long period. Of course, if you continue to wear a cotton undershirt dampened with sweat for a long time, even cotton will smell. Still, for those who do not require strong quick-drying properties in their daily lives, choosing 100% cotton or high-cotton-content undershirts makes sense as an odor-prevention measure.

4. Clothes that smell even though they are washed

While some people who emit a damp smell may be wearing clothes without washing them for days, there are also many who wash them properly. In fact, it is difficult for people who wash their clothes thoroughly every day to think that their own clothing is the cause. Because the clothes do not smell when sniffed after being washed and dried, one assumes there is no problem with the clothing.

However, clothes that harbor stains that cannot be removed by normal washing alone will smell again once they absorb sweat. Multiple factors may be overlapping, such as using too little detergent, overloading the washing machine, insufficient rinsing, leaving laundry for a long time after washing, or taking too long to dry indoors. Also, if dirt accumulates in the washing tub or lint filter, the dirt and bacteria will re-adhere to the clothes you just washed.

Undershirts or shirts that have a concerning odor should sometimes be treated separately from normal laundry. If permitted by the laundry label, dissolve oxygen-based bleach in lukewarm water around 40°C and soak them for a certain period before washing. For areas where sebum easily accumulates, such as the armpits, chest, and back, you can also apply liquid detergent directly to those areas before washing. Chlorine-based bleach should be limited to white items where the label indicates it is safe, as it can cause color fading and fabric damage.

However, there are clothes that will smell the moment you sweat, no matter how many times you soak them. In that case, even if they still look wearable, they have reached the end of their lifespan in terms of odor prevention. Beyond the lifespan of an undershirt until it develops holes, there is a lifespan until it begins to retain odors. If you think it is a waste not to use expensive functional undershirts for a long time, but you end up providing odors to those around you, it is not really worth it.

5. Dry indoor laundry in a short time

During hot and humid seasons, the time it takes for laundry to dry is crucial. Even if the outside temperature is high, if the humidity is also high, clothes do not dry as well as you might expect. It is not so much that indoor drying is bad, but rather that the problem lies in the clothes remaining damp for a long period.

The basic rule is to take your laundry out of the washing machine and hang it up immediately after the cycle finishes, rather than leaving it inside. Space your clothes out, use a fan or circulator to blow air on them, and use a dehumidifier or air conditioner if necessary. Using thick hangers allows air to pass through the inside of the garments, and turning thick items inside out or changing their orientation halfway through will speed up the drying process.

You might think that using plenty of fabric softener will mask the damp smell with a pleasant scent. However, when the damp smell mixes with the fragrance, it creates an even more complex odor. While you may feel reassured by the scent of the fabric softener, those around you are hit with both the damp smell and the sweet fragrance at the same time. What is needed is not to add fragrance, but to remove dirt and dry the clothes in a short amount of time.

6. Even if you wash in the morning, you may not be odorless by evening

As for measures on the skin, the basics are to wash and thoroughly dry areas where sweat and sebum tend to accumulate, such as the armpits, neck, chest, back, and feet. However, scrubbing repeatedly with strong cleansers is not necessarily better. If your skin becomes irritated from over-washing, it can lead to other odors and inflammation.

If you use antiperspirants, it is more effective to apply them to clean, dry skin rather than layering fragrance over sweat. Especially for those who sweat a lot, it is more practical to choose products that contain antiperspirant ingredients rather than just fragrance types. Sweat-wiping sheets are also useful, but if you continue to wear the same sweat-dampened undershirt after wiping your skin, the odor will remain on the clothing.

Therefore, one of the most reliable measures is to change your clothes. Simply changing your undershirt during your lunch break or at the end of the workday can significantly reduce odor. If you work outdoors or in a workplace with poor air conditioning, it is better to change not only your undershirt but also your shirt. Do not keep used clothes sealed in plastic bags for long periods while they are still damp; wash them as soon as you get home. Even if you cannot wash them immediately, simply spreading them out to dry can suppress bacterial growth to some extent.

7. The difficulty of the person being unaware

The tricky part about odor problems is that people get used to their own scent and stop noticing it. Even if the person wearing the same clothes since the morning doesn't notice it, people passing by in the evening can clearly smell it. If you take pride in the fact that you do your laundry and bathe, you are even less likely to think that you smell.

If you are very close to someone, you might be able to tell them, "Your clothes smell a bit damp when they absorb sweat." However, it is difficult to tell a colleague or acquaintance, "You smell," and the same problem repeats every summer without the person having the opportunity to improve.

Therefore, this is not a problem to address only after someone points it out; it is better to take preventative measures on the assumption that you might not be able to smell it yourself. There are objective ways to check, such as having a family member check your clothes after you get home, taking off your sweaty undershirt and smelling it yourself immediately, or comparing long-used synthetic undershirts with new ones.

Conclusion

Simply bathing and doing laundry every day is insufficient as a measure against summer damp smells. It only becomes a complete solution when you include choosing the right clothing materials, preventing the buildup of sebum, drying clothes in a short time, and changing your clothes when you sweat.

For daily life, choose undershirts that contain a lot of cotton, and replace synthetic fiber undershirts early once they start to retain odors. Use the appropriate amount of detergent for laundry, and occasionally reset your clothes using oxygen-based bleach. Clean your washing machine tub regularly, and shorten drying times when hanging clothes. If you sweat a lot while working, prepare a spare undershirt.

The damp smell that drifts on summer evenings does not necessarily indicate that the person is unclean. Rather, it often arises from the clothes of people who work every day, sweat, and do their laundry normally. Even so, it remains an unpleasant odor, so it is worth taking a moment to review your undershirts and laundry methods.