Carbon Inhalation & Blood Oxygen: Understanding the Risk

"Carbon" inhalation usually means **carbon monoxide (CO)** or **carbon dioxide (CO₂)** — elemental carbon (soot) is particulate, not gas.

Carbon Monoxide (CO) — The Real Danger

• Source: Incomplete combustion (engines, heaters, fires, generators).
• Mechanism: Binds Hb with 200-250x affinity vs. O₂ → carboxyhemoglobin (COHb) → **functional anemia + left-shifted O₂ dissociation curve** → tissue hypoxia.
• Symptoms: Headache, nausea, confusion, cherry-red skin (late), coma, death.
• Treatment: 100% O₂ (non-rebreather) → half-life 74 min; HBO₂ (2.5-3 ATA) → half-life 20 min.

Carbon Dioxide (CO₂)

• Normal metabolic product; exhaled.
• High ambient CO₂ (confined spaces, rebreathing) → hypercapnia → respiratory acidosis, sedation, death.
• Not directly from "inhaling carbon."

Elemental Carbon (Soot/Graphite)

• Particulate matter (PM2.5).
• Lung inflammation, fibrosis, cardiovascular risk.
• Does not directly lower blood O₂.

Key Distinction

**CO displaces O₂ on hemoglobin** → lowers *oxygen content* and *delivery*. PaO₂ (dissolved O₂) may be normal, but **oxygen saturation (SpO₂) reads falsely normal** on standard pulse ox — need CO-oximetry.

Install CO detectors. Never run generators indoors. "Inhaling carbon" is vague; CO is the lethal gas.