Hopefully, you never have, or will need to, use an oxygen mask on a plane. Even though the chances of using one are low, passengers are well aware of oxygen masks and how to use them – ‘put your own mask on before assisting’ has been committed to memory subconsciously at this point – thanks to numerous preflight safety demonstrations. 

But what we didn’t know was that said oxygen masks are not actually directly connected to an oxygen air tank. TikTok user JoeSpinsTheGlobe posted a video explaining that the drop down emergency masks are connected to an oxygen generator or oxygen candles. 

@joespinstheglobe if you smell something burning *after* the masks come down, it’s probably this thing. If beforehand… 😬 #science #travel #medicine ♬ original sound – JoeSpinsTheGlobe

When you pull down on the mask, you ignite a primer that heats up the ‘candle’ which burns a solid form of sodium chlorate. When sodium chlorate burns at over 600 degrees Celsius it decomposes the sodium chlorate into oxygen and table salt. 

Which, in all honesty, makes so much more sense considering if you open a valve on an oxygen tank too quickly it can cause it to explode. So, there you have it folks. Then next time you’re on a plane you can share this fun fact with your travel buddy or stranger sitting beside you as a conversation starter. You’re welcome. 

Related story: The most useful travel hacks according to a flight attendant