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Comment by ajhurliman | Hacker News Reader

Oxygen is about 21% of the atmosphere in most places, so 80% CO2 doesn't seem very high (most of the atmosphere is CO2, but there's also other stuff in it albeit at much lower concentrations).

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> 80% CO2 doesn't seem very high

Are you a visitor from Venus? :) https://en.wikipedia.org/wiki/Atmosphere_of_Venus

Joke aside, as other posters say the CO2 concentration is more like 0.04% and even an increase for that is considered a contributing factor in global warming.

You probably wanted to say, most of the atmosphere is Nitrogen (~78%). 80% CO² would be quite interesting, effect-wise: https://pubmed.ncbi.nlm.nih.gov/31759856/

Its not just that a large concentration of CO2 dilutes oxygen- in high enough concentrations it can be toxic. 10% of athmospheric volume as CO2 is lethal in minutes- concebtrations over 30% are lethal in seconds, which is why in cases of CO2 poisoning at high concentrations victims will not appear to have been distressed- they quite simply did not have time to react. There are approximately 89 cases of CO2 poisoning in the US every year, about 2/3 of whom are themselves emergency rescue personell.

That doesn't mean that it isn't bad. From the article itself:

    Normal air contains just 0.04% CO2 but Pfanz was shocked to discover that the concentration around the shrine reached a staggering 80%. "Just a few minutes exposure to 10% carbon dioxide can kill you," he said, "so the levels here are really deadly."

Update: I'm dumb and was thinking about nitrogen, thanks for the correction folks

The atmosphere is about 78% nitrogen. Carbon dioxide forms about 0.04%

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