Primary health impact of carbon monoxide (CO) exposure Which effect best describes the hazard of carbon monoxide to humans at elevated concentrations?

Introduction / Context:
Carbon monoxide (CO) is a colorless, odorless gas produced by incomplete combustion. It is a common indoor and outdoor pollutant, especially from engines, heaters, and poorly vented combustion appliances. Understanding its primary health mechanism is essential for prevention and emergency response.

Given Data / Assumptions:

• Exposure scenarios include enclosed or poorly ventilated spaces with combustion sources.
• Acute health impact is of interest.

Concept / Approach:
CO binds preferentially to hemoglobin to form carboxyhemoglobin, reducing blood’s oxygen-carrying capacity and impairing oxygen delivery to tissues. This leads to hypoxia and can cause headache, dizziness, loss of consciousness, and death. CO does not primarily damage building materials, nor is it a plant growth regulator at ambient levels; asthma exacerbation is more associated with other pollutants (e.g., ozone, particulate allergens).

Step-by-Step Solution:

Verification / Alternative check:
Medical guidance emphasizes rapid removal from exposure and oxygen therapy to displace CO from hemoglobin—consistent with an asphyxiant mechanism.

Why Other Options Are Wrong:

Common Pitfalls:
Underestimating risk in garages and enclosed spaces; even brief exposures at high CO levels can be lethal.

Final Answer:
asphyxiation (suffocation) leading to death.