question_subject:
question_exam:
stats:
keywords:
The correct answer is option 3, 2.5. PM stands for Particulate Matter, which refers to tiny particles suspended in the air. These particles can come from various sources such as vehicle emissions, industrial processes, and natural sources like pollen and dust. The number associated with PM, such as PM 2.5, refers to the size of these particles. PM 2.5 particles have a diameter of 2.5 micrometers or smaller.
These smaller particles are particularly concerning because they can penetrate deep into our respiratory system and even enter our bloodstream, posing a significant health risk. Long-term exposure to PM 2.5 can damage vital body organs such as the lungs, heart, and brain, and result in various health problems, including respiratory and cardiovascular diseases. Therefore, controlling and reducing PM 2.5 levels in the air is essential for protecting public health.