Relative sizes of nanoparticulates

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Relative sizes of nanoparticulates

Postby Wilberforce » Mon Mar 10, 2008 6:22 pm

Relative sizes of nanoparticulates: Tobacco, wood, gasoline, and diesel particle sizes.

Visible light wavelengths are in the 0.4-0.75µm range. Most smoke particles we cannot see because
the particles are too small to scatter light. This means that there is always a much denser smoke than
there appears to be. "Zero visible smoke" cannot be the end goal of combustion effluent reduction.

"The majority of particles emitted from biomass burning, which includes controlled burning and
uncontrolled fires, are ultrafine, with only a small fraction in the larger size range, and with most
of the mass present in particles less than 2.5 ìm in aerodynamic diameter (WHO, 1999). Figure 4.2"


Image

Chart courtesy of the Australian Government/ Department of the Environment and Heritage

http://www.environment.gov.au/atmospher ... mpacts.pdf

Note: this link was published previously
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Postby Wilberforce » Sat Apr 12, 2008 7:09 pm

This chart has been adapted from the above "vegetation burning" chart. The purpose of the chart is to
determine, approximately, the proportion of wood smoke effluent which remains invisible to the naked
eye, due to the extremely small sizes of the majority of the particles. An overall percentage determination
of the invisible portion of smoke was found to be over 98%. This means that more than 98% of effluent
being generated by a biomass fire cannot be seen. Only that proportion of particles which are within the range
of size of visible light can actually be easily seen by humans, and this amounts to less than 2% of the total.

What does this mean: a "zero-visible smoke" chimney thus becomes a sort of volcanic-like exhaust vent,
discharging a cloud of thick, opaque smoke, if viewed under strictly short-wavelength ultraviolet light.

An explanation of nanoparticles and their potential danger to human health:
http://en.wikipedia.org/wiki/Nanoparticle

nanoparticle size distribution picture

Image

How the chart was made:
The original had the horizontal axis (particle size diameter) plotted in logarithmic form. It was converted
point by point to linear form, in order to construct a Riemann sum of the total area under the curve.
(the sum cannot be done in log form, and I did not have access to the original data set)
(note: there is some extrapolation, so the precision of the percentage given may be slightly off.)

For the math-oriented reader:
http://en.wikipedia.org/wiki/Riemann_sum

Data sets:
d (μm) conc Area
0.005 - 15 = 0.15
0.015 - 60 = 0.60
0.025 - 275 = 2.75
0.035 - 549 = 5.49
0.045 - 822 = 8.22
0.055 - 1110 = 11.10
0.065 - 1298 = 12.98
0.075 - 1313 = 13.13
0.085 - 1215 = 12.15
0.095 - 1105 = 11.05
0.105 - 991 = 9.91
0.115 - 873 = 8.73
0.125 - 762 = 7.62
0.135 - 662 = 6.62
0.145 - 557 = 5.57
0.155 - 450 = 4.50
0.165 - 362 = 3.62
0.175 - 296 = 2.96
0.185 - 245 = 2.45
0.195 - 202 = 2.02
0.205 - 168 = 1.68
0.215 - 143 = 1.43
0.225 - 120 = 1.20
0.235 - 100 = 1.00
0.245 - 83 = 0.83
0.255 - 68 = 0.68
0.265 - 56 = 0.56
0.275 - 50 = 0.50
0.285 - 47 = 0.47
0.295 - 43 = 0.43
0.305 - 40 = 0.40
0.315 - 37 = 0.37
0.325 - 33 = 0.33
0.335 - 30 = 0.30
0.345 - 29 = 0.29
0.355 - 27.5 = 0.275
0.365 - 26 = 0.26
0.375 - 24 = 0.24
0.385 - 22 = 0.22
0.395 - 20.5 = 0.205
0.405 - 19.5 = 0.195
0.415 - 18 = 0.18
0.425 - 16 = 0.16
0.435 - 14.5 = 0.145
0.445 - 13 = 0.13
0.455 - 11.5 = 0.115
0.465 - 10.5 = 0.105
0.475 - 10.2 = 0.102
0.485 - 10 = 0.10
0.495 - 9.6 = 0.096
0.505 - 9.2 = 0.092
0.515 - 9 = 0.09
0.525 - 8.6 = 0.086
0.535 - 8.2 = 0.082
0.545 - 8 = 0.08
0.555 - 7.5 = 0.075
0.565 - 7 = 0.07
0.575 - 6.5 = 0.065
0.585 - 6 = 0.06
0.595 - 5.5 = 0.055
0.605 - 5 = 0.05
0.615 - 4.5 = 0.045
0.625 - 4 = 0.04
0.635 - 3.5 = 0.035
0.645 - 3 = 0.03
0.655 - 2.7 = 0.027
0.665 - 2.4 = 0.024
0.675 - 2.2 = 0.022
0.685 - 2 = 0.02
0.695 - 1.7 = 0.017
0.705 - 1.2 = 0.012
0.715 - 1 = 0.01
0.725 - 0.7 = 0.007
0.735 - 0.5 = 0.005
0.745 - 0.3 = 0.003
0.755 - 0.1 = 0.001

d X h = Area of single rectangle
0.01 X Σconc = ΣArea = 145.721 (total area)

visible particles
Σconc from 0.395um to 0.755um = 2.636 (partial area)

2.636 / 145.721 = 0.0181
1- 0.0181 = 0.9819

The bottom line is that:
More than 98 % of the smoke is not visible from "hot-burn" biomass

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Nice Work!

Postby pm2.5mary » Sun Apr 13, 2008 7:27 pm

We have held our ground for 20 years, that 'new' tech stoves don't solve anything. You get a bit less in the visible range, but the output is nastier, more carcinogenic.

Thanks for putting this up!
"Particulate pollution is the most important contaminant in our air. ...we know that when particle levels go up, people die. " (Joel Schwartz, Ph.D., Harvard School of Public Health, E Magazine, Sept./Oct. 2002)
Find more at http://burningissues.org
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Particle size of wood smoke

Postby Ernest Grolimund » Sat Sep 13, 2008 12:43 pm

Thank you Woody for this great find. I was searching desperately for this two years ago and got some limited info that seems to verify this from Dr Naeher et all. I was trying to figure out what size I was up against to see if air filters took it out. Hepa filters let 90% through from what I read and only the IQ Air hyper hepa got most of it. This verifies it and makes me feel better about my purchase. I am very happy with it. It's the health pro plus that Mary has too.

It seems to me that it isn't just the pm or particle size that is the problem with wood smoke. It is the 200 air toxics that are stuck to the pm allong with the water. The combo is heavy and sinks. The pollutants are synergiistic too. It makes sense that better combustion will generate smaller particles and I am grateful to you and Mary for all the great work you are digging up on wood smoke. CAR is the source for information from the whole scientic community on wood smoke. Mary started this whole thing 20 years ago, but you seem to be ready to take her place. I do not know what your credentials are but I can see your searching like a science reference librarian. Better than any I have worked with. I understand that you are a teacher of science. If you are out of work you might want to look into becoming a reference librarian.

Wish we had a camera that could take UV pictures ike an infared camera. Then we could take pictures of the nasty stuff.
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Re: Relative sizes of nanoparticulates

Postby swiper » Mon Dec 28, 2009 5:52 am

This is interesting and thanks for posting.
Very often we smell smoke although we can't see it and this must be why. (I thought my eyesight was failing!)
I wonder if any studies have been done as to what size/concentrations of woodsmoke PM we are capable of smelling?
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Re: Relative sizes of nanoparticulates

Postby taswheezian » Wed Jul 21, 2010 3:46 am

I just wanted to thank you for putting this up. I've been considering whether to get another IQair Health Pro Plus or MGC unit, and this has made my decision for me.

Considering that there are hardly any particles in wood smoke below the .01µm range and the hyper HEPA gets out 99.3% of the 0.003µm particles, it should be very effective. I wonder about the gases, but I think I'd rather have the particulates gone and a good percentage of the gases as well.
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Re: Relative sizes of nanoparticulates

Postby Wilberforce » Sat Jan 15, 2011 6:24 pm

I've reworked the "relative sizes" chart (pictured above) using Riemann midpoints.
It is now clearer and easier to understand.
• The Surgeon General has determined that there is no safe level of exposure to ambient smoke!

• If you smell even a subtle odor of smoke, you are being exposed to poisonous and carcinogenic chemical compounds!

• Even a brief exposure to smoke raises blood pressure, (no matter what your state of health) and can cause blood clotting, stroke, or heart attack in vulnerable people. Even children experience elevated blood pressure when exposed to smoke!

• Since smoke drastically weakens the lungs' immune system, avoiding smoke is one of the best ways to prevent colds, flu, bronchitis, or risk of an even more serious respiratory illness, such as pneumonia or tuberculosis! Does your child have the flu? Chances are they have been exposed to ambient smoke!
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