Environmental Engineering Reference
In-Depth Information
Nanoparticles
Recent advances in technology have created a new type of air pollution—
nannoparticles—microscopic particles that are present in more than
10,000 over-the-counter products. Nanoparticles are so small that a one-
inch line contains 25 million of them.
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The most commonly used
nanoparticle is titanium dioxide. It is present in everything from medicine
capsules and nutritional supplements, to cake icing and food additives,
to skin creams, oils, and toothpaste. At least two million pounds of
nanosized titanium dioxide are produced and used in the United States
each year. The reason these particles are so dangerous is that, in labora-
tory experiments with mice, they damaged or destroyed the animals'
DNA and chromosomes. It is assumed they can have the same effect on
humans.
Because the particles are so small, they can enter the body by almost
any pathway. They can be inhaled, ingested, and absorbed through the
skin and eyes. They can invade the brain through the nose. They can get
into the bloodstream, bone marrow, nerves, muscles, and lymph nodes.
There are no federal regulations concerning the use of nanoparticles in
consumer products.
Good News
It is clear that there has been major progress in the United States in
cleansing the air. In the 1960s, 1970s, and 1990s, Congress enacted a
series of Clean Air Acts that signifi cantly strengthened regulation of air
pollution. These acts set numerical limits on the concentrations of the
major air pollutants and provided reporting and enforcement mecha-
nisms. As a result, between 1980 and 2008, total emissions fell by 54
percent. Particulate emissions fell by 67 percent, sulfur dioxide by 58
percent, nitrogen dioxide by 41 percent, carbon monoxide by 56 percent,
volatile organic compounds by 47 percent, and lead by 97 percent.
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This has happened even as the country's population, economy, and
vehicle traffi c have exploded. For example, Los Angeles, the stereotypi-
cal smog capital of the nation, has gone from nearly 200 high-ozone
days in the 1970s to fewer than 25 days a year now. Many areas of
the Los Angeles basin are now smog free year round. According to the
American Lung Association in 2007, 46 percent of the U.S. population
lives in counties that have unhealthful levels of either ozone or particle
pollution.
