Breathing The Heaviest Non Toxic Gas

That's funny...and at least somewhat dangerous.

In the above video Cody - I assume that's his name, the YouTube channel is Cody's Lab - breathes in sulfur hexafluoride, a dense, inert gas known to deepen the sound of your voice similarly to how helium raises the pitch of your voice.

Cody then immediately breathes in perfluorobutane, an even more dense gas that makes your voice even deeper.

He then comments, "wow, that's actually hard to get back out of your lungs." 

And there's the danger. 

Neither sulfur hexafluoride or perfluorobutane are reactive or toxic. They won't do anything themselves to your body. but they will push the air out of your lungs and make it tough for that air to get back into your lungs. The perfluorobutane, apparently, is even more effective at blocking your lungs from taking air back in because it's just that much denser than air...

• Density of air - approximately 1.225 kg/m³ (source)
• Density of sulfur hexafluoride - 6.17 kg/m³ (source)
• Density of perfluorobutane - 11.21 kg/m³ (at 28.9^oF source)

So, neither of the gases will hurt you, but they will prevent your body from getting air - which sort of includes a rather important thing to your survival, oxygen.

I'm hopeful that Cody had somebody else around to call for help just in case he didn't get air back in quickly enough.

I'm also hopeful that he didn't do that demonstration too frequently because both gases are also potent contributors to the Greenhouse effect, sulfur hexafluoride being almost 24,000 times more effective than CO2 in warming the planet (source), and perfluorobutane being 4800 times more effective than CO2 (source).