Which of the following is false regarding repairable dust: March2010
**Core Concept**
The question is related to the concept of repairable dust, also known as repairable particulates, which are small particles that can be cleared by the body's natural defense mechanisms, such as mucociliary clearance or phagocytosis. This is in contrast to non-repairable dust, which can cause chronic inflammation and damage.
**Why the Correct Answer is Right**
Repairable dust particles are typically small in size, usually less than 10 micrometers in diameter, and are composed of materials that can be easily engulfed and cleared by macrophages and other immune cells. This process is often mediated by the action of surfactant proteins and the enzyme surfactant protein-A (SP-A) which helps to facilitate the recognition and uptake of these particles by alveolar macrophages.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because repairable dust is actually composed of small particles that can be easily cleared by the body's natural defense mechanisms.
* **Option B:** This option is incorrect because repairable dust is not associated with chronic inflammation and damage, unlike non-repairable dust.
* **Option C:** This option is incorrect because the size of repairable dust particles is typically less than 10 micrometers in diameter, not greater than 10 micrometers.
**Clinical Pearl / High-Yield Fact**
It's essential to remember that the size and composition of dust particles play a crucial role in determining whether they are repairable or non-repairable. Understanding this concept is important for clinicians to assess the risk of chronic lung disease in patients exposed to dust particles.
**Correct Answer: B.**