In addition to his Ph.D. in analytical chemistry, Ned Ostojic's biggest business asset is his nose. For the past few decades, he's worked in the field of "odor measurement and control"—a fancy way for saying he’s paid by pet food companies, tuna canneries, and other potentially smelly clients to hunt down noxious aromas and figure out what’s causing them. Scientific American recently profiled Ostojic, describing how he sniffs down stench like a professional.  

The science of smell is complex. Our noses are lined with specialized sensory cells called olfactory sensory neurons. They each have one odor receptor, which detects molecules released by our surroundings and sends messages to our brain so we can recognize and label the odor. The number of smells that exist in the world greatly outnumbers the receptors we have, so molecules can trigger a combination of receptors. Because of this, "smells" are hard to pinpoint. 

That’s why Ostojic uses an olfactometer—a portable machine that detects and measures odor concentration and intensity—for clients like Brooklyn’s Newtown Creek Wastewater Treatment Plant. For them, Ostojic saved the day—and everyone's noses—by creating a ventilation system that absorbed a reeking aroma emanating from the plant’s aeration tanks. He also plans to help Michigan car factories with paint fume odors, and Kentucky landfills with rotting garbage smells.

Technological advances now allow Ostojic and his colleagues to measure and analyze odor compounds, but the jury’s still out on why some scents are horrendous to some, tolerable to others. At the end of the day, smell is a personalized sense—and not even a self-professed “odor specialist” can control that. 

[h/t Scientific American]