It’s a common thing you might hear about sharks. “They can smell a single drop of blood from over a mile away!” But what if I told you that not only is that false, but humans are actually better at smelling something surprising: rain.

Sharks do have an amazing sense of smell and can typically smell blood in water at concentrations as low as 1 part per million, depending on species and chemical composition of blood.

(MORE: Weather.com's Week-Long Exploration Of Sharks, From Their Forecasting Capabilities To Their Public Perception)

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That’s a ratio of 1 part blood to 1 million parts water, and it’s about equivalent to a single drop of blood in a standard backyard swimming pool.

This alone disproves the “one drop a mile away” myth, because the blood becomes more diluted as it gets farther from the source and ocean currents may not carry the molecules toward a shark.

But here’s where things get interesting.

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Petrichor is that warm, earthy scent that comes from a rainstorm, and it gets the “earthy” smell from a chemical compound called geosmin.

Humans can smell geosmin at concentrations as low as 4 to 10 parts per trillion. Not billion… trillion.

(MORE: Rain Smells Different Depending On The Season; Here's Why)

On the low end, that’s 4 geosmin molecules for every 1 trillion water molecules, making the human ability to detect the earthy scent of rain 250,000 times as efficient as sharks’ ability to smell blood.

A quick caveat in defense of sharks

I don’t know about you, but rain doesn’t smell like food to me, and it doesn’t make me hungry.

It might surprise you to learn that the same thing is true for sharks and human blood.

Sharks are attracted to the scent of blood from animals that make up their diet, and fish blood contains amino acids and oils that human (and other mammal) blood doesn’t have. Those amino acids and oils basically tell a shark, “Hey, there’s food over here!”

So if you’re swimming and cut yourself on an oyster shell or step on an anemone, you don’t need to worry about sharks from all around coming to investigate. You should probably get out of the water, though, because there’s a bigger threat lurking in the shallows: bacteria (which is far scarier, in my opinion).

Sara Tonks is a content meteorologist with weather.com and has a bachelor’s and a master’s degree from Georgia Tech in Earth and Atmospheric Sciences, along with a master’s degree from Unity Environmental University in Marine Science.