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Is EPA 2000 report showing a 3.3 times increase?

PostPosted: Fri Nov 09, 2007 10:23 pm
by CaptainAir
Hi there,

Is it just me or does the 2000 EPA report show that the emission rates (g/h) of Phase II certified stoves are 3.3 times higher than their actual certification ratings after extensive use?

Actual data is in Table 3-12, here:

My simple calculations:

The last stove in the table is showing 15 times its certification rating on the field! Am I missing something here?


Is EPA 2000 report showing a 3.3 times increase?

PostPosted: Fri Nov 09, 2007 10:37 pm
by CaptainAir

I forgot to mention...
I would need to include this fact in a document that I need to submit on Monday, so if you can help... Now is the time!



Re: Is EPA 2000 report showing a 3.3 times increase?

PostPosted: Sat Nov 10, 2007 9:48 am
by bodhi
CaptainAir wrote:Is it just me or does the 2000 EPA report show that the emission rates (g/h) of Phase II certified stoves are 3.3 times higher than their actual certification ratings after extensive use?

greetings captain,
unfortunately, the results of the study are disheartening.
here is a link for you (in case you haven't seen it)
"it was clear from the results that emission rates for phase 2 stove models reported as part of the NSPS certification process do not represent emission levels of the same stove models in homes after extended use."
~US EPA, Nov, 2000

please note--->this link provides a couple of names and email contacts for info on the study. maybe you can get more data for your project there.

PostPosted: Sat Nov 10, 2007 10:07 am
by CaptainAir
Thanks bodhi...
And thank you for this forum!!

An email has just been sent to the two EPA contacts.

I am pretty confident with the calculation, but I just want confirmation that I am not missing something.


PostPosted: Sat Nov 10, 2007 2:43 pm
by bodhi
CaptainAir wrote:Thanks bodhi...
And thank you for this forum!!

... my many thanks and massive respect go the Rozenbergs for their great work in bringing the burning issues website to the public.


PostPosted: Sat Nov 10, 2007 5:38 pm
by Wilberforce

You're right, an increase of 330% seems high, but you are using simple averaging. [(sum of n)/n] Other figures
have given emissions degradation estimated to be on the order of 150-200% (I don't recall the figures exactly.)
Compared against the the original EPA certification values, perhaps weighted averaging was used, with respect
to some other factor, such as total fuel mass, burn time, or other. Mean and standard deviation are given as data
attributes. This suggests probability may have been used at some point in the calculations, although throughout
the paper, the author repeatedly makes the statement "no correlation found," so maybe not.

In the tables showing moisture content, it seems they often used very high moisture wood, (table 2-4) some of
what seemed to be almost the equivalent of green wood. Maybe the original certification tests used much lower
moisture wood? In this test, they may be trying to simulate actual, real-world burning practices, where the stove
owner may occasionaly toss in a wet, or green log.

"No direct statistical correlation between emissions and wood moisture, burn rate or the conditions of the stoves
could be made due to the number of variables associated with the real-world in-home use of woodstoves. However,
the particulate emissions for stoves in homes in Portland were on the average higher than for stoves in homes in
Klamath Falls. This result is consistent with the average higher fuel moisture content and burn rate characteristic
of the Portland portion of the study as compared to the Klamath Falls portion."

The type of wood used (softwood vs hardwood) is also a very important factor:

"... A possible explanation of the lack of correlation between particulate and POM emissions is that conifer
cordwood was burned exclusively in Klamath Falls whereas a mixture of conifer and deciduous cordwood was
burned in Portland. Cordwood from conifers has a higher resin content than cordwood from deciduous trees.
Resin is chemically comprised of condensed aromatic rings, hence it is closer in structure to POM compounds
then cellulose or lignin. It is generally believed that, if all else is equal, the higher the aromatic compound content
in a fuel the more POM emissions will be produced upon its combustion...."

Building a good, hot, smoke-free wood fire is really as much of an art, as it is a science. For example, the way the
logs are stacked in the firebox has a lot to do with a fire's efficiency and emissions. The study does not seem to
indicate the conscientiousness of the stove operator: "No direct statistical correlation... could be made due to the
number of variables associated with the real-world in-home use of woodstoves."

Considering optimistic EPA ratings of vehicular fuel economy, (the mileage no one can achieve) a higher value
of woodstove emissions than expected seems normal. This is similar to the normal degradation of automotive
catalytic converters over time, especially if leaded gas (now banned) is used, or if a misfiring spark plug in one
engine cylinder sends raw fuel to the device, thus overheating and destroying it. I used to be an auto mechanic.
You would be amazed at the number of people who simply drive their cars into the ground, then are surprised to
find that the neglected machine breaks down, according to the well-known Law of Murphy.

This all boils down to the idea that the original performance of a product, (which had likely undergone extensive
laboratory testing,) seems to have a normal reduction of performance when put into real-world usage. Especially
if the owner/operator is lacking in motivation as to the product's required maintenence and upkeep:

"Of the 16 stoves inspected, all showed the effects of use. However, only six stoves were degraded to the point
that it was speculated that their condition would significantly affect air emissions. Routine maintenance or minor
repairs could have kept all units in good operating condition if the maintenance or repairs had been done."

"Another key finding of this study is that there is no correlation between actual emission rates of older stoves
and their original certification value, that is, emission rates reported in the certification process do not represent
emission levels of stoves in homes after extended use."

I hope all of this is of some help. You know how tedious it can be to decipher scientific writings. Please let us know
what your findings are. By the way, welcome to the world's TOP smoke pollution awareness website/forum!

Excerpts from EPA documents # 600R00100.pdf and # 600sr00100.pdf (quotes in blue italic font)

PostPosted: Sun Nov 11, 2007 1:05 am
by Dorre
There are several interesting points to note:
* stoves in Klamath Falls emitted on average 7.3 g/h, compared to an average certification value of 4.2 g/h - an increase of 72%
* stoves in Portland emitted on average 14.6 g/h, compared to an average certification value of 3.75 g/h - an increase of 290%

So, the stoves in Portland were no better than old, non-certified stoves which (according to Table 3-10) in the AP-42 study emitted 15.3 g/hr.

Stove degradation could be partly to blame, but another factor is a lack of care by the operator. Prof John Todd, an Australian researcher explains "with a wood heat heater, unlike many other appliances, if you use the heater badly you can produce up to 100 times as much smoke as using it really well” – see

Perhaps the residents of Klamath Falls appreciate that woodsmoke is harmful and take more care to minimize smoke emissions than people living in Portland.

The really important question is not whether stoves emit a certain amount of pollution, but the effect this has on our heath. A team of 25 people studied this in New Zealand and came up with some very interesting answers – in Christchurch adverse health effects of air pollution from woodburners costs the community more than NZ$127 million per year, or more than $NZ2,700 per heater per year.

The researchers acknowledged their estimates are very conservative –mortality was assumed to increase by only 4.3% for every 10ug/m3 of PM10 exposure. Yet research comparing the most and least polluted areas found that mortality increase by 8% for 10ug/m3 of additional PM10 exposure – so the true cost is probably at least double – i.e. about $NZ 5,000 per heater per year. For more information, see

It doesn’t take many wood stoves to create a huge amount of pollution. Those in Portland emitted an average of 14.6 g per hour. So a single stove in a single hour can pollute an area 100 metres x 100 metres to height of 10 metres at 146 ug/m3 – nearly 15 times the concentration required (over long periods) to increase mortality by 8%.

A set of powerpoint slides summarising some of the health effects and how the costs were calculated is available at:

Christchurch has banned the installation of new woodstoves, except ultra-low emission models rated < 1g/kg installed as replacements for more polluting models. All woodstoves emitting more than 1 g/kg will have to be removed after 15 years use.

Given the effect woodstoves are having on people’s health, even that seems rather lenient. An alternative approach would be to introduce a polluter-pays levy proportional to the cost to people’s health, which is greater in urban than rural areas.

PostPosted: Sun Nov 11, 2007 12:19 pm
by Wilberforce
Since everyone is posting hyperlinks on this thread, I'll throw you some:

Be sure to follow all of the links given on the web page, especially Particulates and Atmospheric
dispersion modeling
. WIKI has articles on Smoke, Benzopyrene, Polycyclic aromatic hydrocarbon,
and so on. Why not take an hour to read and learn about the poisons you are inhaling when you get
a whiff of that so-called 'nice wood-smoke smell.'

More links:
PARTICULATE MATTER: ... /index.htm ... matter.pdf