Carbon monoxide (CO), an air pollutant when inhaled readily binds with the hemoglobin in the blood stream to form a life threatering compound known as

The correct option is Carboxy hemoglobin.

Let us understand the step-by-step physiological explanation of how this compound forms and why it is dangerous:
1. Normal Oxygen Transport: Under normal conditions, hemoglobin in our red blood cells binds reversibly with oxygen (O₂) in the lungs to form oxyhemoglobin, which distributes oxygen throughout the body.
2. Carbon Monoxide Exposure: Carbon monoxide (CO) is a colorless, odorless gas. When inhaled, it quickly diffuses across the lung membrane into the bloodstream.
3. High Binding Affinity: Carbon monoxide has a binding affinity for hemoglobin that is roughly 200 to 250 times greater than that of oxygen. Because of this extremely strong attraction, CO easily displaces oxygen and binds to the iron molecules in hemoglobin.
4. Formation of Carboxyhemoglobin: The chemical combination of carbon monoxide and hemoglobin results in the formation of a stable, bright red coordination complex called carboxyhemoglobin.
5. Toxicity and Danger: Because carboxyhemoglobin is highly stable, the hemoglobin becomes locked and loses its ability to transport and release oxygen to bodily tissues. This leads to systemic oxygen deprivation (hypoxia), which can cause tissue damage, loss of consciousness, and death, making it a life-threatening compound.