If someone doesn't have access to washing their body and their clothes then for sure they will over time have a very large population of bacteria on them and these bacteria are the source of the smells. Even human urine is not necessarily a powerful reek until bacteria get to work on it.
Body odor happens when bacteria on your skin come in contact with sweat. Our skin is naturally covered with bacteria. When we sweat, the water, salt and fat mix with this bacteria and can cause odor. The odor can be bad, good or have no smell at all.
Starting at about age 40, human bodies begin to subtly change the way that omega-7 unsaturated fatty acids on the skin are degraded. As these acids are exposed to oxygen in the air, the change creates a smell, called “nonenal” after the 2-nonenal molecule that is produced in the breakdown process.
Not all homeless people smell, and plenty of people with homes do. Many homeless people don't have access to a private bathroom where they can shower every day, or do laundry regularly.
Trimethylaminuria is a disorder in which the body is unable to break down trimethylamine, a chemical compound that has a pungent odor. Trimethylamine has been described as smelling like rotten or decaying fish.
A person with kidney failure may have breath that smells like ammonia or urine. Serious liver disease can make breath smell musty or like garlic and rotten eggs. Compounds that are transported through the blood can also be released through your sweat glands. That can make your armpits and skin smell bad.
Foetor hepaticus is a feature of severe liver disease; a sweet and musty smell both on the breath and in urine. It is caused by the excretion of dimethyl disulphide and methyl mercaptan (CH3SH)2, arising from an excess of methionine.
Apparently there is something called “Occupant Odor.” These odors come from the detergents you use, cooking smells, cleaning supplies, and room fresheners. These scents then occupy spaces like curtains, carpets, cushions and pillows. Combined together, the meshing of these scents creates your distinct home smell.
Scientists have found that dozens of illnesses have a particular smell: Diabetes can make your urine smell like rotten apples, and typhoid turns body odor into the smell of baked bread. Worse, yellow fever apparently makes your skin smell like a butcher's shop, if you can imagine that.
An olfactory hallucination (phantosmia) makes you detect smells that aren't really there in your environment. The odors you notice in phantosmia are different from person to person and may be foul or pleasant. You may notice the smells in one or both nostrils.
Living a healthy lifestyle can help reduce the smell of nonenal. Drinking plenty of water dilutes fatty acids. Similarly, drink green tea, which breaks down the compounds responsible for causing the nonenal smells. Exercise and eat nutritiously.
Many believe the distinct odor in nursing homes is urine, but it really it's something called nonenal. The good news is that the Japanese have created a product from natural persimmon that removed what American visitors to the homes of elderly relatives or nursing homes sometimes speak as “old person smell.”
Trimethylaminuria (TMAU) is an uncommon condition that causes an unpleasant, fishy smell. It's also called "fish odour syndrome". Sometimes it's caused by faulty genes that a person inherits from their parents, but this isn't always the case. There's currently no cure, but there are things that can help.
The most common cause for a belly button smell is poor hygiene. All areas of the body need to be washed regularly to stay clean and healthy. Skin is home to trillions of bacteria, which develop naturally and are usually harmless. The belly button has folds of skin that provide a place for bacteria to grow.
Body Odor
Poor digestion causes imbalances with the bacteria in your digestive tract. In addition to the chemicals made from the digestion process causing bad breath, the odor is also absorbed into the body and then emitted through your skin when you sweat.
"The evolutionary theory behind why stress sweat smells so bad is that it's believed the odor triggers an alert response in our brains," Hafeez said in an email to CNET. "When humans smell this type of perspiration, we can tell it's the physical response to a mental concern, like fear or anxiety."
Hair is another place where bacteria like to hide. If you still smell a strong body odor after a shower, consider shaving the hair in your armpits, groin, and chest. The hair's surface is a perfect place for bacteria to call home, and it's harder to eliminate them from the hair than your bare skin.
A weird smell in a house can come from numerous sources, including appliances, furniture, carpets, fabrics or issues like mold or mildew. Occasionally, odors may be caused by sewer gas, natural gas leaks or animals that have died between walls, in attics or under decks.
Food and drink spills, leftovers and crumbs could all contribute to smells accumulating in your room. Check under your bed, your mattress and within your covers for any spilled food, and return plates and bowls to the kitchen as soon as you're done to avoid the smell of leftovers lingering in the morning.
Blocked Drains
Any type of blockages, whether they are partial or full, can prevent waste water from properly leaving your home. Over time, this stagnant water sitting in the pipes can build up bacteria and produce pungent odors throughout the night.
Chronic kidney disease (CKD) is one possible cause of having an ammonia taste in your mouth, sometimes called “ammonia breath.” Some people describe ammonia breath as having a metallic taste, while others have reported that it smells similar to urine.
Smelling of the breath is common after having certain food or in the morning, but with people suffering from fatty liver conditions, it remains throughout the day. The breath may have a distinct sulfur and musty smell throughout the day. It is an obvious sign of fatty liver disease and should not be ignored.
The scent of fetor hepaticus is more distinct and smells like sulfur. It happens as a result of liver disease. Learn more about fetor hepaticus and how to manage the condition.