My first thought: what do they mean by “run out of oxygen”? Does the band play until they pass out? If so, how will anyone know, given that the box is soundproofed and opaque? Do they just play until a certain CO2 level is reached? Do they have sensors and an alarm in the box?
My second thought: how long will the band actually play? Or, to phrase the question in another way, how long does it take to use up all the oxygen in the box? Apparently, this isn’t the first time a death metal band has played in the box (though it is the first time this has been done in London). Surely there must be some stats on this, like average length of time spent in the box.