Hi @Ag8n, with regards to the medical situation vs equipment, it sounds like the particle sizes they are measuring are relevant for (1) respiratory particles (< 5 um) that can travel deep into the lungs and get caught there, and (2) particles that are so small they can enter the bloodstream. The estimated maximum size for being able to enter the bloodstream is 100 nanometers (0.1 um), but as noted in my comment above, those particles are very difficult to measure. I'd love to know exactly what equipment these facilities are using for both size fractions!
With regard to what we are measuring, I think we can discern down to ~ 1 um diameter, thought probably with at least +/- 1 um precision. So, I'd really say we're hoping to look at the PM10-PM2.5 fraction. Some of those would be respirable (< 5 um), some would be inhaled but not respired (5 < x < 10 um). Does that get at the question you're asking? I'm not quite sure I understood correctly. Thanks!
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Yeah, that is part of the question.
The medical devices had direct access to the blood stream and lungs. So particle number and size was critical. It was usually measured with a laser beam. The particle would partially block the laser beam, and you could determine the size by the amount of light that got through. The down side. You could only do one particle at a time. You either had to dilute or go to other methods to get more answers.
This method is commonly used in HEPA filters in the medical industry. So now there are hepa filters being used for particulate removal. I'm trying to get the two fields to sync together. That's where my problem is.
Any help is appreciated. Thank you.
Sorry, I didn't finish the instrument explanation. After determining the size of a particle,most instruments find out how many particles are greater than 5 micron and how many are greater than 0.5 micron in a set period of time. This is then displayed or printed. Heck, some will even give you a bell shaped curve, if you want it.
Other instruments will use the laser diffraction pattern. The last I saw, they needed you to select a " model" for the calculation. That may have changed. These instruments weren't as popular.