RACHEL’s Hazardous Waste News #132

=======================Electronic Edition========================

The most dangerous products of incineration are tiny, invisible,
pollutioncoated particles released into the atmosphere. In the
air pollution business, these are known as “fine particles.”
Despite the best available control technology, incinerators emit
large quantities of such particles, which typically measure two
micrometers or less in diameter. A micrometer is a millionth of a
meter and a meter is 39 inches. Pollution control devices like
Venturi scrubbers and baghouse filters are not very efficient at
trapping these small particles, so to save money for incinerator
operators (and thus encourage incineration, which is the stated
goal of the EPA), the U.S. Environmental Protection Agency has
declared it “OK” for incinerators to emit large quantities of the
smallest particles. Federal law says that an incinerator is
allowed to emit 180 milligrams of particles with each cubic meter
of air (or 0.08 grains with each cubic foot of air). There are
437.5 grains in an ounce. One large incinerator smoke stack may
emit 100,000 cubic feet of air every minute, day in and day out,
or 52 billion cubic feet per year. It would be legal for such an
incinerator to emit 300 tons of particles yearly. Typically, half
of these particles will measure 2 micrometers or less in diameter
and thus will be “respirable,” which means that you and I can
breathe them into the very bottom of our lungs because nature has
provided us with no defense against particles this small. From
our lungs, they can pass directly into our blood. (See RHWN #131,
where we discussed the penetration of these fine particles into
human lungs.)

The National Academy of Sciences, in AIRBORNE PARTICLES
(Baltimore: University Park Press, 1979), discussed the health
dangers of fine particles from many points of view. The
“background level” of these fine particles in uninhabited regions
of Canada is 1 to 3 micrograms in each cubic meter of air; in the
rural Midwest, you’ll find 5 to 12 micrograms in each cubic meter
of air. This is not a “natural” background level; it represents
pollution created by humans. Nevertheless, this background level
is a good standard against which to judge the allowable emission
of particles from incinerators. The allowable emissions from an
incinerator exceed background concentrations by anywhere from a
factor of 15,000 to a factor of 180,000. The EPA is relying upon
dilution to protect you. They will argue that, by the time those
particles reach your lungs, they will be diluted in a lot of
fresh air and thus won’t be quite so far above background levels
when you breathe them. But this, of course, depends upon how
close you live to an incinerator, how the wind currents go,
whether there are thermal inversion conditions in your local
atmosphere, and so forth. There is growing evidence (to be
presented next week) that the EPA’s dilution strategy isn’t safe.

Fine particles remain airborne for long periods of time, and
before they fall to earth they can travel several hundred miles
or even farther. They can present a danger to humans all along
their route. Fine particles weigh so little that they do not
respond predictably to the pull of gravity. The smallest air
current keeps them aloft. These particles are so small that rain
drops do not wash them from the atmosphere. You are no doubt
familiar with the force of air being pushed ahead of a truck
barreling down the highway; it gives your car a push as it goes
by. In the same way, raindrops (which measure 500 to 9000
micrometers in diameter) push air ahead of them as they fall, and
they knock fine particles aside instead of washing them to earth.

Increasing the concentration of fine particles in the atmosphere
is not good for people. Hardest hit are those with bronchitis and
asthma, those who are very young or old, and those who exercise
outdoors. Breathing through your mouth (which is one of the first
things people do when they exercise, play sports, or jog)
increases the intake of fine particles into the lungs. In
addition, some healthy people absorb 50% more fine particles into
their lungs than the average. The reasons for this are not
understood. One particularly important aspect of fine particles
is that they carry into our lungs pollutants that could not
otherwise get there. In this sense, fine particles have
synergistic (multiplier) effects with other pollutants. The
Academy said, “The generally accepted view of synergism extends
beyond potentiation [increasing a pollutant’s power] to include
the role of toxic vector [carrier]. Such gases as sulfur dioxide
are probably either adsorbed to the particulate surface or
absorbed into the particles, and thereby transported into the
alveolar regions [in the deep lung], where they exist in high,
localized concentrations. These localized high concentrations [in
the lung] could not be produced without particles. Accordingly,
sulfur dioxide sorption to particulate matter might effectively
allow sulfur dioxide penetration into the alveolar regions at
even nominal environmental concentrations of the gaseous
pollutant.” In other words, “normal” or “acceptable” levels of
sulfur dioxide may be made dangerous by the presence of fine
particles.

“In summary,” said the National Academy, “particulate atmospheric
pollutants may be involved in chronic lung disease pathogenesis
as causal factors in chronic bronchitis, as predisposing factors
to acute bacterial and viral bronchitis, especially in children
and cigarette smokers, and as aggravating factors for acute
bronchial asthma and the terminal stages of oxygen deficiency
(hypoxia) associated with chronic bronchitis and/or emphysema and
its characteristic form of heart failure (cor pulmonale).”
–Peter Montague, Ph.D.

Descriptor terms: lung disease; particulates; air pollution; air
quality; canada; bronchitis; emphysema

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