Olfaction, or the sense of smell, is one of the most primitive and powerful human senses. It is directly linked to the limbic system, the brain region responsible for emotion and memory. While most people agree on the appeal of a rose or freshly baked bread, there is a fascination with “weird” scents—aromas that are technically chemical, biological, or industrial in nature. Here are ten weird scents that many people love, along with the science behind them.

1 Old Books

Old books have a warm, slightly sweet smell that many readers recognize immediately. The scent mainly comes from the slow breakdown of lignin, a natural polymer found in wood-based paper.

As paper ages, lignin decomposes and releases aromatic compounds such as vanillin, the same compound responsible for the smell of vanilla. These chemicals gradually accumulate in the pages, creating the distinctive “old book” aroma that many people associate with libraries and antique bookstores.

2 Permanent Markers

Permanent markers have a strong, sharp smell due to organic solvents in their ink. Many markers contain chemicals such as xylene, which evaporate easily and quickly reach the nose when the cap is removed.

Solvents like xylene can affect the nervous system when inhaled in large amounts. Studies on inhalant exposure show that such chemicals may produce light-headedness or temporary neurological effects, which some people interpret as a mild feeling of euphoria.

Because of these effects, inhaling marker fumes intentionally is dangerous and is considered a form of substance abuse.

3 The Smell of Rain (Petrichor)

The familiar earthy scent that appears when rain falls on dry ground is often called petrichor. One of the main chemicals responsible for this smell is geosmin, a compound produced by soil-dwelling bacteria known as actinomycetes.

When raindrops hit dry soil, they trap tiny air bubbles that burst, releasing microscopic particles containing geosmin into the air. These particles are then carried by the wind, allowing people to smell the characteristic earthy scent.

4 Gasoline

Many people say they enjoy the smell of gasoline, even though gasoline vapors are toxic. Gasoline is a complex mixture of hydrocarbons and contains chemicals such as benzene.

When inhaled, these vapors can affect the nervous system. Research has shown that exposure to gasoline fumes can stimulate the brain’s dopamine reward pathway, which may create a brief feeling of pleasure or stimulation.

However, benzene is a known carcinogen, and inhaling gasoline fumes is harmful; therefore, intentional exposure is strongly discouraged.

5 Our Own Odor

It may sound strange, but many people find their own flatulence less unpleasant than someone else’s. Psychologists believe this reaction is related to familiarity and biological instincts.

Humans tend to be less sensitive to odors produced by their own bodies because the brain already recognizes them as familiar. In contrast, unfamiliar bodily odors may elicit stronger reactions because the brain treats them as potential warning signals of germs or disease.

This difference in perception helps explain why people often tolerate their own smells more easily than others’ smells.

6 Freshly Cut Grass

The smell of freshly cut grass is widely associated with parks, gardens, and summer days. The scent comes from chemicals known as green leaf volatiles (GLVs).

Plants release these compounds when their leaves are damaged, such as during mowing or cutting. The chemicals act as distress signals, helping nearby plants prepare their defenses against insects or environmental stress.

Although the compounds serve a protective role for plants, humans often interpret the scent as fresh and pleasant because of its strong association with outdoor environments.

7 New Tennis Balls

Opening a fresh can of tennis balls releases a distinctive smell that many people recognize and love. Tennis balls are stored in sealed, pressurized cans to preserve their bounce and internal pressure until they are used. When the seal is broken, trapped air and vapors escape from the container.

The scent mainly comes from materials used in the ball’s construction, including the rubber core, the felt covering, and adhesives applied during manufacturing. The pressurized can keeps these vapors contained, which is why the smell becomes noticeable as soon as the container is opened.

8 The “Pool Smell”

The strong smell people associate with swimming pools is often assumed to come from chlorine itself. In reality, the scent is mainly caused by trichloramine, a chemical formed when chlorine reacts with substances introduced by swimmers.

When chlorine mixes with sweat, body oils, or urine, it produces chloramines such as trichloramine. These compounds evaporate into the air above the water, creating the familiar “pool smell.”

Ironically, a strong pool odor can actually indicate that the chlorine is reacting with contaminants rather than simply being present in clean water.

9 Nail Polish

Many nail polishes have a sweet or fruity smell while they are drying. This scent comes from solvents such as ethyl acetate and butyl acetate, which help keep the polish liquid inside the bottle.

These solvents evaporate quickly after application, allowing the polish to harden on the nail. During evaporation, they release vapors that naturally smell like fruit aromas, such as pear or banana, which explains why the scent may seem pleasant despite being a chemical solvent.

10 New Car Smell

The smell inside a brand-new car is created by off-gassing, a process in which materials slowly release trapped chemicals into the air.

Modern car interiors contain many synthetic materials, including plastics, vinyl, adhesives, sealants, and fabrics. More than 50 different volatile organic compounds (VOCs) can evaporate from these materials inside a new vehicle.

These vapors mix together to produce the recognizable “new car smell” that many people associate with purchasing a new vehicle.