認識PM 與生命的奧秘

認識PM 與生命的奧秘

"Particulate matter," also known as particle pollution or PM, is a complex mixture of extremely small particles and liquid droplets. Particle pollution is made up of a number of components, including acids (such as nitrates 氮and sulfates硫), organic chemicals, metals, and soil or dust particles.

The size of particles is directly linked to their potential for causing health problems. EPA (環保局) is concerned about particles that are 10 micrometers in diameter or smaller because those are the particles that generally pass through the throat and nose and enter the lungs. Once inhaled(吸入), these particles can affect the heart and lungs and cause serious health effects. EPA groups particle pollution into two categories:

         

• "Inhalable coarse particles, (能吸入的粗粒)" such as those found near roadways and dusty industries, are larger than 2.5 micrometers and smaller than 10 micrometers in diameter(直徑). 
• "Fine particles," such as those found in smoke and haze, are 2.5 micrometers in diameter and smaller. These particles can be directly emitted(釋出) from sources such as forest fires, or they can form when gases emitted from power plants, industries and automobiles react in the air.

PM2.5的「PM」，是英語『particulate matter』的縮寫，意為『細顆粒物』。

PM50、PM10、PM2.5 是三個臨界值，空氣裡並非只有這三種直徑的顆粒物，50微米以下或者以上的，任何直徑長度的顆粒物都有。

PM50是肉眼可見的臨界值，可以進入鼻腔，但是無法繼續前進。
當PM50在我們鼻腔積累到一定程度，我們就會想擼鼻涕、挖鼻屎。

PM10是可以到達咽喉的臨界值，PM10積累於咽喉所在的上呼吸道，積累到一定程度，我們就想吐痰，所以痰要吐不要咽。

PM2.5是到達肺泡的臨界值。 上呼吸道擋不住，它們可以一路下行，進入細支氣管、肺泡。

     

PM2.5和細菌一般大小。
細菌進入血液，血液中的巨噬細胞（免疫細胞的一種）立刻就會把它吞下，它就不能使人生病，這就如同老虎吃雞。

可是，PM2.5是沒有生命的，巨噬細胞吞了它，如同老虎吞石頭，無法消化，最終被噎死。巨噬細胞macrophages大量減少後，我們的免疫力就會下降。

不僅如此，被噎死的巨噬細胞，還會釋放出有害物質，導致細胞及組織的炎症。可見PM2.5比細菌更致病，進入血液的PM2.5越多，我們就越容易生病。

呼吸系統要好好保養....跟免疫系統 (autoimmune systems)也有很大關係....

我覺得，人體真奧妙！造病環境很可怕！！

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Justin Lai 改編

12/19/2015