Which one of the following air pollutants combines with haemoglobin and reduces the supply of oxygen to the h… - UPPSC 2017

UPPSC 2017

Biochemistry & Nutrition

Easy

Appeared in: UPPSC 2017

Explanation

Carbon monoxide (CO) is a colorless, odorless gas produced from incomplete combustion of carbon-containing materials.
It has an affinity for hemoglobin that is about 220 times greater than that of oxygen.
When CO binds to hemoglobin, it forms a stable compound called carboxyhemoglobin (CO-Hb).
The formation of CO-Hb prevents red blood cells from transporting oxygen to the body's tissues, leading to systemic hypoxia.
Even low concentrations of CO can significantly reduce the oxygen-carrying capacity of the blood, affecting organs with high oxygen demand like the brain and heart.

Option A: Sulphur dioxide is a respiratory irritant that primarily affects the lungs and airways by causing inflammation and bronchoconstriction. It does not bind to hemoglobin in a way that displaces oxygen.
Option B: Carbon dioxide does bind to hemoglobin as part of the normal physiological process of respiration to be transported to the lungs for exhalation. This binding is reversible and does not have the toxic, high-affinity displacement effect seen with carbon monoxide.
Option C: Ozone is a highly reactive gas that acts as a powerful oxidant, causing damage and inflammation to the respiratory tract lining. It does not enter the bloodstream to bind with hemoglobin.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Toxicology and effects of air pollutants on oxygen transport as background academic context rather than a clinical decision trigger.
Recognizing the signs of CO poisoning (headache, dizziness, nausea, confusion) is a critical nursing skill, as early intervention with 100% oxygen is vital.
Patient education on CO sources (faulty furnaces, generators, car exhaust) and the importance of CO detectors is a key preventative nursing role.
What if? If a patient is a heavy smoker, their baseline carboxyhemoglobin level is already elevated (5-10%), making them much more susceptible to the effects of acute CO exposure. The nurse must consider this when assessing risk and symptoms.

How to Approach the Question

First, identify the core of the question: which pollutant interferes with oxygen transport by binding to hemoglobin.
Recall the functions of hemoglobin and its primary role in carrying oxygen.
Evaluate each option based on its known toxicological properties.
Differentiate between pollutants that are respiratory irritants (Sulphur dioxide, Ozone) and those that cause systemic effects via the bloodstream.
Distinguish between the normal physiological binding of carbon dioxide and the pathological, high-affinity binding of carbon monoxide.
Select the pollutant that is well-known for its ability to out-compete oxygen for hemoglobin binding sites, leading to hypoxia.

Concept Tested & Keywords

Concept Tested: Toxicology and effects of air pollutants on oxygen transport.
Stem keywords: air pollutants, combines with haemoglobin, reduces supply of oxygen
Lead-in keywords: Which one

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