User talk:Whoistrm

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I'm just looking at your recent change to the wiki PM2.5/PM10 page (about PM2.5 not referring to particles <2.5µm etc.). It seems your sole reference is a blog post by 'Diamond Env' which doesn't strike me as particularly reliable. The other perhaps more reliable article you link to (Thoracic and respirable particle definitions for human health risk assessment) says: "In 1997, the EPA extended size-selective sampling to include fine particles indicated by PM2.5 (particles with a nominal mean aerodynamic diameter ≤ 2.5 μm) "

I have also done a bit of research on this today (don't get me wrong, I don't have a PhD in Aerosol Science, but am an aeronautical engineer) and it seems that PM2.5/10 is measured using a 'size-selective inlet'. Now the diameter of the 'size-selective' inlet for PM2.5/10 is approximately 2.5µm/10µm respectively (see the table at the end of page 405 on http://www.tandfonline.com/doi/pdf/10.1080/027868299304589 ), so I am not sure how it can be expected to measure particles that are also ABOVE that diameter - as they will never fit through the size-selective inlet. I am not saying you are wrong, just I think you need to provide more reliable and specific information backing up your claim.

I followed the links to ISO7708 in Diamond Env's blog, and it states (see http://ftp.cdc.gov/pub/Documents/OEL/02.%20Kuempel/References/ISO_1995-Report%20No%207708.pdf ) that the THORACIC fraction is given by a log-normal distribution with mean aerodynamic diameter of 11.68µm, but it doesn't mention anything about PM10 there (the respirable fraction refers to a log-normal distribution with mean aerodynamic centre of 2.5µm).

Also, the ACTUAL ISO document referred to in that blog post (ISO23210:2009) states this: "This International Standard describes a measurement method for the determination of mass concentrations of PM10 and PM2,5 emissions, which realizes the same separation curves as those specified in ISO 7708:1995 for PM10 and PM2,5 in ambient air. The method is based on the principle of impaction. During sampling, the particle fraction is divided into three groups with aerodynamic diameters greater than 10 µm, between 10 µm and 2,5 µm and smaller than 2,5 µm. " Pjrobertson (talk) 06:58, 23 February 2016 (UTC)