Been There, Smelled That explores the aromas of places around the world. Travel writer Maggie Downs investigates some of the world’s most potent smells, looks at how odor cultivates a connection to place, and presents how humans engage with smells, from scents that have endured generations to the latest innovations in aroma-making.

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Years ago, when I was a newspaper reporter at my first job out of college, I wrote a series about a teenager waiting for a heart transplant. When the lifesaving organ finally became available, I was lucky enough to be invited into the operating room to witness the procedure.

I barely remember any of it. In my head, I can only visualize it like a collage of images, as quick and jarring as a trending TikTok. I can’t even picture the room. There’s only a gaping white spot, like a cartoon backdrop that’s been erased. It’s as gone as last night’s dream.

What I do remember is the smell. When the surgeon used a sternal saw to open the boy’s chest, there was a distinct and pronounced odor. At that moment, my mind was seared with the scent of bone and burning.

Since then, every once in a while, I’ll smell a certain type of fire that instantly drops me back into that operating room. That’s how odors work. Smell is our only sensory system that does not pass through the thalamus before it’s routed to the cerebral cortex. Instead, odors take a direct route to the parts of the brain that are responsible for emotions and memory. So it doesn’t take much to trigger a flood of associations related to that aroma.

That’s also why there’s a big business for manufactured fragrances—and not just the good ones.

There’s an office park just off Highway 10 near Palm Springs in a location that’s simultaneously isolated enough to be unsettling but close enough to a Best Western to feel slightly comforted. There, you’ll find a pale building that looks like it was snatched from the TV show Severance. It’s the kind of place where you’d go to find a notary or talk with somebody about your mortgage. Except this place is actually a business that sells unforgettable sensory experiences.

This company creates ambient systems that include fragrance, smoke, mist, and sprays, all designed to inspire emotion. One part of the business is focused on creating the kind of immersive experiences you’d find at amusement parks, museums, and live events for marketing or entertainment purposes. The other part of their business involves creating the same kind of immersive experiences, but for the military, law enforcement, and first responders.

That’s why their scent catalog reads like a list of Julie Andrews’s favorite things juxtaposed with a horror reel. Fresh-cut grass, seasoned chicken, and cinnamon bun right alongside blood trauma, burning flesh, and corpse. God forbid cotton candy ever gets mixed up with meth lab.

My first thought was OF COURSE. There’s nothing that the military-industrial complex won’t weaponize for its own gain. I can’t wrap my head around diffusers for gingerbread and mustard gas coming from the same place.

But I do think this highlights how important scent is to our lives. A scent memory is like an invisible thread that connects the past with the present and affects our response in the moment.

Obviously, for first responders, learning to identify smells can prepare them to make critical decisions with a quicker response. Burning electrical smell is an essential cue for firefighters to know what they’re battling. Similarly, flight crews have used sensory training to prepare for a variety of emergency scenarios. I don’t know who needs cyanide or nitric acid or heated brake pads, but those are there too.

About an hour away from the sensory factory, there’s a Marine Corps combat center used for urban warfare training. It’s a mock city about the size of downtown San Diego, and in addition to realistic classroom, market, and hotel settings, complete with real-life role players, the center also includes underground tunnels, weapons caches, riverbeds, courtyards, and compounds.

I haven’t gotten confirmation on the exact atmospheric technology the Marines use there, but I’d wager it involves scent. It takes time to process what you see or hear. Plus, there are optical illusions that trick the eye and sounds designed to confuse. But a smell? A smell is always true. Even more importantly, it gets embedded in your memories.

Amid the chaos of violence and upheaval, people follow their instincts. And there’s nothing that triggers an instinct faster than a scent.

“Smell information translates straight into behavior or mood and evokes whole memories,” says smell expert Tim Jacob in The Atlantic.

And it can put you right back into a location, even when that place is fake.