What most offends your olfactory senses? Week-old dirty running socks? Rotten eggs? A well-ripened dirty diaper? Think of the odor that curls your nose hairs and sends you into fits of revulsion. Now forget about it, because the stinkiest thing you have ever encountered is like the finest perfume compared to the world’s smelliest substance.

The foul fiend that holds the dubious distinction of the most putrid perfume is known as thioacetone. Its scent goes beyond unpleasant. Its level of revulsion rises to nearly super villain status and sears its imprint on the noses and nightmares of all who encounter it.

This description of thioacetone’s odiferous qualities are far from subjective. Consider the reports of German researchers in the city of Freiburg in 1889. They were working with thioketones and manages to separate thioacetone from a neutralizing compound. The result produced “an offensive smell which spread rapidly over a great area of the town causing fainting, vomiting and a panic evacuation.”

An 1890 report from the Whitehall Soap Works in Leeds refers to the odor as “fearful,” which is really saying something, considering the offensive conditions of a late-19th century soap factory.

More than half a century passed until scientists conducted an intensive study of thioketones as sources of new polymers. The most in-depth analysis took place at the Esso Research Station in Abingdon, UK, where Victor Burnop and Kenneth Latham recorded their own encounter with thioacetone:

“Recently we found ourselves with an odour problem beyond our worst expectations. During early experiments, a stopper jumped from a bottle of residues, and, although replaced at once, resulted in an immediate complaint of nausea and sickness from colleagues working in a building two hundred yards away. Two of our chemists who had done no more than investigate the cracking of minute amounts of trithioacetone found themselves the object of hostile stares in a restaurant and suffered the humiliation of having a waitress spray the area around them with a deodorant. The odours defied the expected effects of dilution since workers in the laboratory did not find the odours intolerable … and genuinely denied responsibility since they were working in closed systems. To convince them otherwise, they were dispersed with other observers around the laboratory, at distances up to a quarter of a mile, and one drop of either acetone gem-dithiol or the mother liquors from crude trithioacetone crystallisations were placed on a watch glass in a fume cupboard. The odour was detected downwind in seconds.”

One unfortunate encounter with thioacetone will undoubtedly make you long for any of the 20 most-recognizable smells, or be willing to pay $3,200 for a pint of Chanel No. 5 perfume.