[Stoves] Particulate size distribution

Andrew Heggie aj.heggie at gmail.com
Wed Feb 1 03:49:37 CST 2017


On 1 February 2017 at 07:50, Crispin Pemberton-Pigott
<crispinpigott at outlook.com> wrote:
> Dear Andrew
>
> At the risk of being corrected by Harold, from whom I learned most of this, I will try to answer.

Harold from SETAR? He has  posted he recently on general points of the
scientific method, perhaps he might help us out here also??


>
>>Are you saying woodsmoke produces very few particles below 2.5?
>
> No, it produces nearly no particles above that cut point.

Okay I see the logic now, so the size classes from stoves are of the
most likely type to reach deep into the bronchial passages.
>
>>>A major concern is the nasal passages provide a direct path by diffusion to the brain, which dispenses with lung arguments. They also enter the lung cells by diffusion of course.
>
>>In the past you said the nasal passage was good at stopping PM10,
>
> Correct. By impact. It turns out the airways are also good at growing the particles by depositing moisture on them making them easier to catch and later expel.
>
>>...are you now saying this path is likely to make these sizes of concern now?
>
> Yes. Very small particles 10-20 nanometers can diffuse directly through the body.

These are 100 times smaller than we have been discussing

>>What other particles (like fly ash) get detected? Can the two be discriminated?
>
> Sometimes. So far everyone, just about, is happy to hear about PM2.5.

Well recent discussions indicate that extrapolating  like this can
lead to a big discrepancy in attributing problems caused. Without an
expert's guidance it's pretty difficult to find or assimilate
knowledge about particulates amid the media storm.
>
>>Back to the distribution, obviously an equal mass below 0.6 microns will have a heck of a lot more particles than above 0.6. As we move forward it is likely the metrics will change from mass or mass-equivalent to counts and size.
>
> Yes. Nothing else to add.



Thanks for your trouble Crispin, I wonder how much I must have in my
lungs by now, a very swift calculation  assuming clean air of about 15
micro gram/m^3 and 40% retention suggests about 2 grams  unless the
body has excreted some. Mind it's likely much worse from bonfires and
sitting in the open cab of a tractor for most of my working life.




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