[Stoves] Particulate size distribution

[Andrew Heggie]

On Tue, 31 Jan 2017 16:18:23 +0000,Crispin Pemberton-Pigott
<crispinpigott at outlook.com> wrote:

>Dear Andrew
>
>With reference to PM sizes: wood and coal fires make particles which have a central 'mass' of PM0.6. Half the mass is above and half below a great deal of the time during tests. In other words they are small.

Thanks Crispin, I've changed the subject line
>
>There are few particles in the size of PM2.5 which is why that number was chosen. If the equipment is a little off it makes nearly no difference to the mass detected.

Are you saying woodsmoke produces very few particles below 2.5?
>
>I have quite a number of tests made using a GRIMM 11-R which gives size 'bins' and the size profile can be easily seen. The GRIMM fortunately reports counts as well as the mass if a density is supplied. The density can be applied per bin so it can be calibrated very well - far better than a Dusttrak which reports PM1.0, PM2.5, PM4 and PM10.
>
>The cleaning up of diesel emissions was in large part the reduction of PM size below the detection limit of optical instruments. Two things have resulted: equipment that can now detect optically to a much smaller particle, and even better combustion.
>
>The health and social impact of nanoparticles is not well known at all. The idea that they penetrate deep into the lungs hides the fact they are also expelled very easily.

One of the reports suggested only 40% of the <PM2.5 got exhaled I think.

>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, are
you now saying this path  is likely to make these sizes of concern
now?

>
>"Differences" in the particles will centre on the chemistry.  Diesel particles will be far more homogeneous that wood smoke particles which will vary a great deal during the process of a burn. Actually you can smell the difference over a period of minutes. Diesel smells like diesel.

Yes, I'm guessinng we are mostly concerned with the health risk from
sooty (black carbon) particles containing polycylic aromatic
compounds. Are these particles full specturm from <2.5 to >PM10. What
other particles (like fly ash) get detected? Can the two be
discriminated?
>
>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 some sort of weighting for number of particles embedded will need
to be ascertained to better reflect the chances of causing a problem.
>

AJH