A dangerously low oxygen level—usually below 92%—can cause shortness of breath, confusion, chest pain, or fainting. It’s often triggered by lung or heart conditions like COPD, asthma, or heart ...

Elizabeth Cooney is a cardiovascular disease reporter at STAT, covering heart, stroke, and metabolic conditions. You can reach Liz on Signal at LizC.22. Oxygen is the breath of life, right? Because it ...