Most odor blockers do not destroy scent molecules—they instead use chemicals to surround and trap smelly molecules.

Molecules such as DDT, a synthetic insecticide, and PFAS—"forever" chemicals used to make products resistant to heat, water, and grease—have historically been used across various industries but are now known to be harmful. Microbes that can convert some of these substances into nontoxic products, such as water and carbon dioxide, have already been identified, with ongoing research to find others.

Scent stimulates our olfactory sensor neurons high in the nasal cavity, and the brain attaches labels to those scents. But when we eat, chemicals from the foods travel from our mouths and throat to those neurons. We have roughly 400 odor receptors, and they can be used to decipher more than 10,000 different odors (or more than one trillion by some calculations), including the nuances of different foods.

In a 2025 paper, researchers reported they'd created a proof-of-concept device that bypasses typical olfactory pathways and instead exploits an alternative—the trigeminal nerve in the nose—to detect a few strong scents. The nerve typically helps detect the temperature of inhaled air or the presence of irritants.

Olfactory training, which involves repeatedly smelling a selection of strong odors, teaches your brain to familiarize itself with experiencing smells over a lengthy period, typically multiple months. This can be useful for patients who lose their sense of smell for myriad reasons.

Using spectrographic techniques, scientists determine the chemical composition of planetary atmospheres, comets, and other objects in space. Combining these chemicals in labs on Earth has revealed locations in space that smell like nail polish remover, rotten fish, and urine.

Once a person is accustomed to a specific odor, their neurons have trouble continuing to respond to that smell because of that familiarity. That's why humans may not notice when their house smells like trash until they leave the house and then return to it.

Have you ever picked a travel destination by smell? This Atlas Obscura piece cultivates a list of the most distinct-smelling spots in the world. Learn about these obscure scents to potentially book a trip to a spring that smells like rotten eggs, or a desert valley filled with frankincense trees.

In experiments where people were exposed to a literal fishy smell they were less willing to cooperate with others in economic games requiring trust, but that wasn't the case when they were exposed to another bad odor—the smell of flatulence.

This excerpt from a Mythbusters episode takes on the smell-of-fear question, comparing the sweat composition of individuals exposed to snakes, rats, and scorpions with that of people exercising. Molecularly, the sweats are different to a gas chromatography machine, but to most noses would be indistinguishable.

Smell is imbued with more emotion than visual memories, and research indicates that smell triggers a significantly greater effect on amygdala activation. Scientists believe these powerful responses occur partly because smell signals bypass the thalamus and go directly to the amygdala and hippocampus, brain areas involved in emotion and memory.

Scientists compared the smells of babies and teenagers and identified some of the compounds that make teens smelly. Carboxylic acids present in teens, they wrote, seemed to give off an "earthy, musty, or cheesy" scent. This 2024 research could help inform future odor-control products.

Processes such as air movement and heating cause food to lose aroma molecules, which studies have shown play a major role in our sense of taste. While losing these molecules to the environment leaves fewer to be processed during consumption to intensify flavor, it can also produce previously nonexistent aroma compounds or release previously trapped ones, altering or enhancing the food's flavor.

Myriad bacteria contribute to our body odor, but research suggests that Corynebacterium species are strongly associated with the bad smells emanating from adults. Staphylococcus and Cutibacterium genera may also play leading roles.

As part of a scientific bet, neurobiology researchers dragged a chocolate bar across the grass and sought to see if a human could track it—she could. This led to a more in-depth experiment on human olfactory capabilities and behavior when other senses were blocked.

This paper explores how biomolecular data on past scents can be teased out and then transformed into olfactory museum experiences, adding another component to our understanding of archaeology.

The work identified the 25 most frequent words used to describe body odors across languages, ranked by frequency, and found that "sweaty" topped the list, followed by "sour" and "stinky."

Studies show that microorganisms in chicken manure can break down the hydrocarbons in crude oil without producing toxic by-products. Scientists have also explored avoiding the environmental risks of chemical dispersants and synthetic adsorbents by using human hair and peat moss to adsorb crude oil, which can be taken up by their cuticles and porous structures, respectively.

CFCs, which are used in old refrigerants, air conditioners, and aerosol sprays, do not react with atmospheric molecules. Once they reach the stratosphere, ultraviolet radiation breaks chlorine atoms off of them, which can each break apart more than 100,000 ozone molecules, thinning Earth's protective layer against ultraviolet radiation.

This chemical, used to keep ticks, fleas, mosquitoes, and other nuisance bugs away, is used by an estimated one-third of the US population and has been available to consumers since 1957. Researchers theorize that multiple mechanisms may be at work to deter bugs, including perhaps masking or confusing bugs' olfactory receptors.

That's according to one estimate published in 2014. This figure far exceeds earlier estimates of a human smelling ceiling around 10,000 odors. The newer figure is derived from experiments in which volunteers agreed to sniff varying scents. Researchers mixed odor components and had volunteers sniff the brews to detect subtle scent differences.

Odor is more effective than both visual and verbal cues for triggering autobiographical recall in Alzheimer's disease, according to 2021 research.

Scientists are trying to figure out if there are unique receptors that respond to the molecules that make up flavors we associate with calcium, blood, batteries, and other items that often escape dinner menus. Taste researcher Dr. Danielle Reed says the minimum evidence for a taste category typically involves identifying dedicated receptors and then removing them to show the taste vanishes.

Receptors for "bitter" tastes evolved to detect potentially harmful plant chemicals, such as nicotine. The receptors also trigger bacteria-fighting responses, including waving hairlike projections to bat away bacteria, ordering the release of bacteria-killing nitric oxide, and calling for antimicrobial protein reinforcements.

The product was marketed toward women and framed excessive sweating as a medical disorder that needed to be addressed with the product.

Despite their eco-friendly name, biodegradable plastics often require industrial composting, which most areas lack, to decompose the uncommon compounds found in them. This means they may linger in landfills or contaminate conventional plastics in recycling bins.

Through a series of processes that collectively make up phytoremediation, plants can take up pollutants from soil and water through their roots, then break them down, release them as less harmful gases, or store them within their cells. Any plants that sequester heavy metals or other toxins must be removed and managed after the environment is decontaminated.

Ever had the experience of receiving a bottle of wine with a janky, less-than-favorable odor? This Esquire article ventures to answer this question and offers the explanation that the culprit is likely corked wine. Read to understand why corks can create a moldy or musty scent, and feel emboldened to send a corked bottle back for something with improved quality.

Although they make up no more than 10 out of every million molecules in the ozone layer, ozone provides outsized protection by absorbing the most energetic wavelengths of ultraviolet radiation. This absorption increases thermal energy in the stratosphere, causing temperatures there to rise with altitude.

Developed as replacements for ozone-depleting substances in refrigeration and air conditioning systems, these compounds are released through leaks in and ongoing use of these appliances, as well as from various industrial processes. They can remain in the atmosphere for thousands of years and have warming potentials that are a thousand to tens of thousands of times greater than those of carbon dioxide.