Color psychology has long had a place in marketing and advertisements. Red’s association with strength and energy, for example, has made it a favorite among sports networks and gyms. Blue, on the other hand, is more likely to inspire feelings of loyalty and calmness, so banks and other professional organizations favor the hue as a consequence. But what about a muddy looking greenish-brown?

One such color, specifically Pantone 448C, was recently chosen in a marketing survey as the most unappealing color. Participants associated the color with the words “tar,” “death,” and “dirty.” Since this didn’t exactly put it on the top of the list for anyone hoping to sell a product, Australia decided to slap it onto cigarette packaging in 2012. Paired with graphic photos showing the health effects of smoking, the muddy color was meant to deter potential purchasers, and it seems to be working — the country’s cigarette sales have fallen since then.

Now the United Kingdom is hoping the unsavory color will be similarly lucky for them. Lawmakers have approved legislation standardizing the packaging of tobacco products, and Pantone 448C will be the only color allowed.

But why is it this particular shade is so effective at keeping people away?

Color consultant and author Angela Wright told CNN the color has been used to deter people before. In the 1960s, color consultant Faber Birren was tasked with stopping employees from lingering in the bathroom on long breaks.

“The company asked him, ‘Can you improve the working area so they don’t have to leave all the time and use the restrooms?’” Wright said. “Birren actually took a different view and painted the restrooms in a color similar to Pantone 448C. And nobody wanted to spend time in the restrooms after that.”

She explained that the shade’s resemblance to human waste may be why it drives people away so well.

“It makes perfect sense that smoking packets would use a vile green that looks like bodily fluids and makes people feel slightly nauseated,” she explained.

However, all colors are created equal according to Leatrice Eiseman, executive director of the Pantone Color Institute. She told The Guardian that the color had “deep, rich earth tones,” and was popular for sofas. Someone even created a twitter account where the color could defend its reputation.