[Stoves] PM emissions from engines

[Andrew Heggie]

 On Tue, 6 Jun 2017 03:03:23 +0000,Crispin Pemberton-Pigott
<crispinpigott at outlook.com> wrote:

>
>This throws even more confusion on the subject, gasoline engines produce more PM than diesel engines, presumably running on standard fuels.

The article is misleading in that very few spark ignition engines are
direct injection, though the proportion may be rising. Also
particulates are not small molecules but rather large agglomerations
of compunds.

It does lead to another  question though and that is what is more
significant, the number of particles or their mass? Plainly if we
restrict our attention to PM4, as perceived wisdom is larger particles
are efectively filtered out by the nasal passage, then as particle
mass goes up with the cube of it's dimensiones then a device producing
many small pm1 particles can emit 8 times as many particles as one
emitting pm4 before it reaches the same mass.

>
>"The laboratory studied the emissions of 7 gas engine vehicles equipped with direct-fuel-injection systems. The research found that they emit from 10 to 100 times more particulates than modern diesel engines. In fact, they have higher particulate emissions than older diesel without particulate filters.?"

In this country all diesel vehicles have to have particulate traps and
many have urea injection to reduce NOx (itself a precursor of
particulates amongs other associated problems)


Therein lies another worry: Nikhil's scepticism  does raise the
question about premature death in that many of the people affected
will have spent most of their lives exposed to higher levels of
particulates, in UK the majority of adults smoked in the 50s, we had
lead in fuel and open burning much of which has decreased to
negligible amounts. Surely we won't see an improvemt in life
expectancy for a generation?

Don't let this drift too far as vehicles are not a pertinent subject
though particulate emmissions are but using Nikhils equitoxity concept
what are the differences between fine fly ash (50% silica) and black
carbon with Poly Cyclic Aromatic compounds adsorbed on their surface?

Andrew (in the good enough camp)