Environmental Engineering Reference
In-Depth Information
Tambora in the Dutch East Indies generated a huge aerosol veil that capped virtually
all the north hemisphere, preventing the sun rays from reaching the Earth with their
usual efficiency. The result was an ecological, sanitary, economic and social
disaster.
As mentioned just above, a small reduction in diameter size is enough to reduce
dramatically the volume of a particle and, as a consequence, its being more prone to
stay suspended in the air and be carried by the wind and other atmospheric
phenomena. Nowadays industrial plants, waste incinerators, internal-combustion
engines and, in general, all systems working by burning something emit dust, and
the use of increasingly high temperatures delivers in the atmosphere ever smaller
and more mobile particles. Also explosions are sources of particulate matter. New
weapons like, among others, depleted-Uranium or Tungsten bombs work because
of the very high temperatures they reach when they hit their mark. That heat is
enough to have bomb and part of the target vaporize. In a matter of seconds, as soon
as the atoms and the small molecules of that gaseous-state substance are cold
enough, they consolidate to form particles.
But particles made by human activities are not restricted to high-temperature,
incidentally created ones as an unwelcome side effect.
In the late 1950s scientists realized that matter, when its size is in the nanometer
order, behaves in a then-unexpected way, a way that could be exploited in many
industrial applications. That was the notion that begot Nanotechnology (or Nanotech,
as the name is usually shortened), something that can represent a revolution to our
society, if only for its being the hugest financial investment in Man
s history.
Artificial matter can be created starting from molecules or even from atoms and
assembled into a new lattice (crystalline structure) that we call nanoparticles,
i.e. entities with a size generally not exceeding 100 nm. Those are the basic
constituents, sophisticated bricks of even more sophisticated buildings, of products
with extraordinary properties. Applications are as numerous as they are varied and
the limit to nanotechnologists seems to be imagination. In most cases utilizations
and products are still at an experimental stage, but in other they have already taken
the form of everyday products and, as a matter of fact, reached a multitude of
unaware users. Cosmetics like, for example, sun screening and beauty creams;
clothing, sports equipment, antimicrobial bandages, household appliances (washing
machines, air conditioners, refrigerators, etc.), self-cleaning glass and tiles, paints,
scratch-resisting coatings, swimming-pool disinfectants, drugs and even food are
but some of the nanotech goods already commercially available.
All those things are undoubtedly exciting and promise to make life easier, but the
problem, or one of the problems, is that we are not sure they do not have a negative
impact on the environment and on living organisms
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health. We are not sure simply
because no truly exhaustive research has preceded the marketing of most products
and what, in a way, is more important, has preceded the investments. The conse-
quence is that the investors seek to recoup their investment as quickly as possible
and are not particularly enthusiastic about waiting for the results of researches for
which they should spend more money fearing a negative answer.
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