[Stoves] particulate size retention

[Andrew Heggie]

On Fri, 25 May 2018 at 03:57, Crispin Pemberton-Pigott <
crispinpigott at outlook.com> wrote:


> Now we can understand why there is such controversy about the health
impacts of nanoparticles.

I'm nowhere near yet but hoping I'm beginning to get a handle on some of
it, with help from discussion here.

> Burning grass, as in veld fires, creates a huge amount of ultrafine PM.
This has been going on for eons, literally. How much additional material
like that is produced by, say, diesel engines, the cleanest of which
produces hardly any detectable PM1 at all. It has been pointed out that the
engines shift the PM from larger sizes into the range that has nearly no
efficiency at being impacted in human lings. Diffusion, yes, and that
applies to the nose, eyes, anything I suppose.

Yes I suppose that is still an agrarian practice in some places, and of
course certain species of plants are adapted to  surviving wildfires, gum
trees being one and giant redwoods another .  Burning of cereal stubble was
banned here in 1993 so there must be comparative data somewhere to show a
change in background particulates in July.

The diesel engine business is attracting so much criticism from articles in
the Lancet  and elsewhere but given that publication also seems to have
misinterpreted the results from the African study we discussed some months
back I  don't give them the credence I once would have. I still don't
understand how a most modern (Euro stage 5 and above) diesel  which has a
particulate filter and NOx catalyst can still be considered unacceptable
yet it produces a hundred times less particulate than one twenty years ago,
or so we are told. I have a particular interest here as I spent 30 years
driving diesel plant with no cabs or filtration and do have some
respiratory problems.

If we are allowed to assume that black carbon particles from incomplete
combustion are potentially among the worst things for causing health
problems, because they are small enough to get into the lungs and act as
carriers of PAHs, then we have to assign a weighting to the particle size
and yet I still don't understand if the there is a correlation between the
total mass of particulates that reach the lungs  or the numbers. Plainly a
particle that is half the dimension  needs 8 times as many to make the mass
of one larger one.

> Our lives are full of ultrafine particles. We should not be making
precise claims for something we cannot even measure well, let alone
characterise. Smoke is bad for you. Fine. Let's get on with deleting it. We
don't have to create an inverted pyramid of wild guesses standing on that
single point.

As I said before I wholly agree with this point else there is not much
reason for our continuing discussion.

Andrew