The smell of benzene added to gasoline has an addictive effect and the ability to stimulate memories, which is enticing to some people.
Have you ever rolled down the windows at a gas station just to sniff a big hit and turned out to be the only lunatic doing it? Firstly, don’t worry… you are not alone. I would stop right behind you and do the same! Second, there is a perfectly reasonable scientific explanation for this seemingly odd craving.
What Makes Fuel Smell Good?
Gasoline is a complex mixture of over 150 chemical compounds, many of which are hazardous to health, including a Public Health Statement published by the CDC. The compound that gives gasoline its strong and gassy odor — which some of us are drawn to — is a hydrocarbon called benzene. Well, manufacturers don’t just add benzene to give us a little treat. The benzene in gasoline provides better fuel efficiency and improves engine performance. Maybe the lovely scent was just a happy coincidence.
- Houbigant Fougère Royale, a perfume from one of France’s oldest perfume houses, contained benzene, which contributed to its strong scent (Photo: Guiclan/Wekimidea Commons)
benzene in a bottle
The pleasant smell of benzene in gasoline may be just a coincidence, but historically, benzene’s sweet and aromatic smell made it a common ingredient in aftershaves and perfumes in the early 19th century. We can’t be crazy because we like the smell of perfume, right? However, all of these uses were later phased out after scientists determined that benzene is carcinogenic and toxic. Inhaling hydrocarbons like benzene can affect all of our organs, most commonly the lungs. It can cause a severe type of inflammation hydrocarbon pneumonitis.
- Hydrocarbons like benzene can cause pneumonia, a serious type of inflammation. (Image credit: kung_tom/Shutterstock)
Am I sniffing death at the gas station?
Understandably, you are probably outraged that the benzene in gasoline can affect your health. But don’t worry as all substances in gasoline are in tiny and controlled concentrations that are harmless to us. The benzene content in gasoline is only about 1% by volume Mobile Source Air Toxics (MSAT) Rules. Despite its very low concentration, your nose can still absorb it. This is because the odor is pungent even at 1 part per million benzene in the air. It also spreads faster because it evaporates quickly in the air. It’s definitely not because some of us have a “super smell”! But what is it about benzene that makes some of us crazy about it? Well, there are two main theories.
- Even at 1.0% benzene by volume in gasoline and 1 part/million benzene in the air, the odor is so strong and pungent that we can still smell it very well (Image credit: Krakenimages.com/Shutterstock)
Theory 1: Reminisce
Have you ever noticed that it is your sense of smell that leads you back to a very special memory? The smell of freshly baked cookies might remind you of Christmas at home; The smell of an old book might remind you of the hours spent hunched over your favorite novel. There is a very specific reason for this, which you can read about here! However, the short explanation is that the area of the brain that senses smell, unlike the other senses, is close to the areas responsible for emotions and memory. Your brain therefore associates a strong smell with an important memory. One reason some of us like the smell of gasoline is that we associate it with a fond memory. It could have been a fun family outing or long drives with your grandpa.
- Strong odors, such as benzene in gasoline, can attach to core memories
Theory 2: Gasoline SHOTS, anyone?
The second theory that explains why we like the smell of gasoline is that benzene has euphoric effects on the brain. In other words, snorting benzene can get you high. This is because inhaling hydrocarbons like benzene can numb nerve receptors and weaken the central nervous system like an anesthetic. Studies show that this activates the brain’s mesolimbic pathway, commonly referred to as the reward pathway. The reward here is a shot of dopamine, the feel-good hormone that temporarily makes you feel good.
- (Image credit: Pikovit/Shutterstock) (Caption: The green area of the brain highlighted above, called the mesolimbic pathway, is rich in dopaminergic proteins neuronswhich, when activated, release dopamine, the happiness hormone.)
Fair warning, activating the mesolimbic pathway to release dopamine is how most drugs of abuse work their evil magic. The feeling you get when there is a rush of dopamine in your system is somewhat addictive. So the occasional smell of benzene while filling your gas tank is harmless, but intentionally sniffing it can cause addiction and health problems.
Is it just fuel?
Interestingly, gasoline isn’t the only thing that contains benzene. Other common items you may have smelled that contain benzene are tennis balls, nail polish, and paint. If you’ve ever caught yourself sniffing those things curiously, now you know why.
The reason you flare your nostrils to get a nice big whiff at gas stations is the strong but pleasant smell of benzene, which is added to gasoline. Whether benzene does this by evoking a fond memory, releasing a shot of dopamine, or a combination of both is still being researched.
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