问题,在讨论“PM2.5”,有标准化的理解粒子还是不包括?这是所有的2.5微米和小吗?还是一切* * 2.5和0.1微米之间?同样可吸入颗粒物包括所有PM2.5吗?和“大小”指定的方法是什么?这是一个空气动力大小从某种惯性撞击器配置(虚拟或真实),或从散射光学尺寸,还是别的?背景——PM2.5和其他类颗粒的“热门话题”。从维基百科的微粒;大小、形状和溶解性物质)(https://en.wikipedia.org/wiki/Particulates大小,_shape_and_solubility_matter): > […]10-micrometer大小并不代表一个严格的呼吸道和non-respirable粒子之间的界限,但已经约定了空气颗粒物的监测监管机构。 Because of their small size, **particles on the order of 10 micrometers or less (coarse particulate matter, PM10)** can penetrate the deepest part of the lungs such as the bronchioles or alveoli; when asthmatics are exposed to these conditions it can trigger bronchoconstriction. >Similarly, so called fine particulate matter (PM2.5), tend to penetrate into the gas exchange regions of the lung (alveolus), and very small particles (ultrafine particulate matter, PM0.1) may pass through the lungs to affect other organs. Penetration of particles is not wholly dependent on their size; shape and chemical composition also play a part. To avoid this complication, simple nomenclature is used to indicate the different degrees of relative penetration of a PM particle into the cardiovascular system. Inhalable particles penetrate no further than the bronchi as they are filtered out by the cilia. Thoracic particles can penetrate right into terminal bronchioles whereas PM0.1, which can penetrate to alveoli, the gas exchange area, and hence the circulatory system are termed respirable particles. In analogy, the inhalable dust fraction is the fraction of dust entering nose and mouth which may be deposited anywhere in the respiratory tract. The thoracic fraction is the fraction that enters the thorax and is deposited within the lung's airways. The respirable fraction is what is deposited in the gas exchange regions (alveoli). >The smallest particles, less than 100 nanometers (nanoparticles), may be even more damaging to the cardiovascular system. Nanoparticles can pass through cell membranes and migrate into other organs, including the brain. Particles emitted from modern diesel engines (commonly referred to as Diesel Particulate Matter, or DPM) **are typically in the size range of 100 nanometers (0.1 micrometer).** [...] ---- From AirNow.gov's [Particle Pollution (PM)](https://airnow.gov/index.cfm?action=aqibasics.particle): > - **Coarse dust particles (PM10) are 2.5 to 10 micrometers in diameter**. Sources include crushing or grinding operations and dust stirred up by vehicles on roads. > - **Fine particles (PM2.5) are 2.5 micrometers in diameter or smaller**, and can only be seen with an electron microscope. Fine particles are produced from all types of combustion, including motor vehicles, power plants, residential wood burning, forest fires, agricultural burning, and some industrial processes However, EPA.gov's [Particulate Matter (PM) Basics; What is PM, and how does it get into the air?](https://www.epa.gov/pm-pollution/particulate-matter-pm-basics#PM) says: > - **PM10:** inhalable particles, with diameters that are **generally 10 micrometers and smaller**; and > - **PM2.5:** fine inhalable particles, with diameters that are **generally 2.5 micrometers and smaller.** [![enter image description here][1]][1] [Source](https://www.epa.gov/pm-pollution/particulate-matter-pm-basics#PM) [1]: https://i.stack.imgur.com/JIdjz.jpg