What is PM 2.5 known for in terms of health risks?

PM 2.5 refers to particulate matter that is 2.5 micrometers in diameter or smaller. These fine particles are known for their ability to penetrate deeply into the lungs and even enter the bloodstream, posing significant health risks. Due to their small size, PM 2.5 can evade the body's natural defense mechanisms, making them more dangerous than larger particles.

When inhaled, these particles can cause a variety of health issues, including respiratory diseases, cardiovascular problems, and even adverse effects on the nervous system. Their ability to remain in the body for extended periods leads to chronic health problems, as they can cause inflammation and exacerbate existing conditions. This characteristic makes PM 2.5 particularly concerning in terms of public health and air quality regulations.

In contrast, the other options do not accurately reflect the health implications of PM 2.5. The ease of clearance from the body is not true for these fine particles, and they certainly pose more than minimal health risks while affecting a broad range of health outcomes beyond just respiratory health.