If breathing carbon dioxide seems uninviting, the density of the air will appear worse.

如果说呼吸二氧化碳令人生厌的话，那么空气的密度就显得更为糟糕。

youdao

This occurs because during NREM sleep the automatic, metabolic system has exclusive control over breathing and the body uses less oxygen and produces less carbon dioxide.

这是因为在非快速眼动睡眠中，自动的新陈代谢系统对呼吸有排他的控制，身体消耗更少的氧气，产生更少的二氧化碳。

youdao

Only after several inadequate breaths under such conditions, resulting in the considerable elevation of carbon dioxide and reduction of oxygen in the blood, is breathing effort adjusted.

在这种情况下，只有在几次呼吸不足出现，导致血液中二氧化碳大量增加和氧气减少后，呼吸的力度才得到调整。

youdao

Breathing in two hundred parts per million of carbon monoxide will cause the first signs of poisoning.

VOA: special.2011.01.25

Usually the treatment for carbon monoxide poisoning involves breathing in large amounts of oxygen.

VOA: special.2010.02.02

This will happen within two hours of breathing in this amount of carbon monoxide.

VOA: special.2010.02.02

Katie Haines, 31, of Wokingham, drowned in the bath after breathing in carbon monoxide from a leaking boiler.

BBC: Wokingham man sets up charity after wife's gas death

His wife, Katie Haines, 31, of Wokingham, drowned in the bath after breathing in carbon monoxide from a leaking boiler.

BBC: Husband welcomes carbon monoxide decision

Rescuers have long monitored patients' breathing tubes for carbon dioxide to make sure the device was correctly placed in the windpipe instead of the esophagus.

WSJ: New Strategies to Revive Victims of Cardiac Arrest