“Chlorine” is a track about the cleansing power that music has on the narrator. Chlorine, while being a deadly chemical, is used to eliminate unwanted substances. As stated in the lyrics, the chemical is compared to a “vibe” or “beat.” While the chlorine has poisonous properties and could potentially cause harm, the narrator just can’t get enough.

A similar idea is found in an earlier song when Tyler says,

You gotta bleed to know
That you’re alive and have a soul

In both cases, the concept of pain, or something which would generally be unwanted is flipped on its side and used as a metaphor for that which is beneficial.

On January 22, 2019, Twenty One Pilots released an official music video for Chlorine, featuring a tiny, horned, anthropomorphic bipedal monster they call “Ned”.