translation.en: When methane built up, or carbon dioxide built up, or oxygen was diminished, the birds would swoon before people would -- so it acted as an early warning system: Hey, get out of the mine. Things aren't going so well.
translation.zh: 当甲烷或二氧化碳含量过高， 或者氧气减少时， 金丝雀会比人类先昏过去-- 就好像一种预警系统： “伙计，快点出矿去，有什么不太对劲。”