May 1, 2006
LOS ANGELES -- The Southland’s air quality agency today announced a
preliminary policy initiative to address potential harmful health effects
from ultrafine particles, an unregulated air pollutant produced by diesel
engines and other combustion sources.
“Research on ultrafine particles has raised a cautionary flag indicating
they may be more harmful than larger particles that currently are
regulated,” said William A. Burke, Ed.D., Governing Board Chairman of the
South Coast Air Quality Management District.
In response, Burke announced today that AQMD will develop a component of
its 2007 Air Quality Management Plan addressing the sources, outdoor levels,
health effects and potential control measures for ultrafine particles in the
Southland. A draft of the plan is scheduled to be released this summer.
Burke made his remarks at a media briefing during AQMD’s three-day
international conference, “Ultrafine Particles – the Science, Technology and
Policy Issues.” The conference featured presentations on the latest
scientific findings regarding the health effects, ambient levels, control
methods and policy implications for ultrafine particles.
Ultrafine particles are among the tiniest of pollutants studied to date.
Current federal and state regulations set health standards for PM10 and
PM2.5, particles respectively smaller than 10 micrometers and smaller than
2.5 micrometers. Ultrafine particles are those smaller than 0.1 micrometers
(100 nanometers) -- more than 10,000 times smaller than the head of a pin
and in the same size range as viruses. (See following chart.)
The Size of (Really Little)
Things
|
Object |
Size (micrometers) |
Size (nanometers) |
|
Head of a pin |
1,000-2,000 |
1,000,000-2,000,000 |
|
Dust mite |
200 |
200,000 |
|
Human hair |
60-120 |
60,000-120,000 |
|
Red blood cells |
2-5 |
2,000-5,000 |
|
DNA |
.002-.012 |
2-12 |
|
Ultrafine particles |
<0.1 |
<100 |
One micrometer =
one millionth of one meter Source:
www.nano.gov
One nanometer = one billionth of one meter
Health scientists are concerned about the potential health effects of
ultrafine particles for several reasons. When inhaled, ultrafines are
deposited along the length of the airways, from the nose to deep alveolar
lung tissue. Due to their minute size, studies indicate they can migrate
from the airways to the central nervous system and organs throughout the
body including the heart and brain. Research at the University of
California, Los Angeles, has shown that ultrafine particles penetrate cells
and wreak extensive damage to mitochondria, the body’s cellular energy
factories.
In addition, ultrafine particles can be shaped like tiny branches, rather
than round balls, and have hundreds to thousands of times more surface area
than the same mass of PM2.5 particles. This greatly increased surface area
could make ultrafine particles capable of transporting much larger amounts
of toxic compounds into the body.
Dozens of epidemiology studies have documented the adverse health effects
of PM10 and PM2.5 pollution, including increased asthma and other
respiratory diseases in children, decreased lung development in children,
low birth weight of infants and premature births, cardiovascular disease
including atherosclerosis (narrowing of the arteries) and premature deaths.
To date, the small numbers of emerging clinical and epidemiological studies
focused solely on ultrafine particles have found the potential for health
effects.
Most ultrafine particles are formed as engine exhaust gases exit the
tailpipe and become diluted in air. Measurements along the 710 freeway have
found about 1 million ultrafine particles in a space the size of a sugar
cube. Outdoor concentrations of ultrafine particles tend to be highest in
the western Los Angeles Basin, where most vehicle traffic is concentrated,
and somewhat lower in the inland valleys.
While engineers have successfully designed new heavy-duty diesel engines
and emission control devices that have reduced the total mass of particles
emitted, this has led to an increase in the number of ultrafine particles
produced. In addition, engine lube oils can create ultrafine particles
containing metals.
During AQMD’s conference, speakers outlined some of the steps needed to
control ultrafines:
- Further optimization of the design of both engines and their emission
control systems to reduce both the mass and number of particles emitted;
- Continue reduction of sulfur content in fuels; and
- Establish a standard for lube oils that will result in lower ultrafine
particle emissions.
“This conference is a call to action,” Burke said. “We need to fully
understand ultrafine particles and their health impacts sooner rather than
later so that we can take the necessary steps to protect public health.”
AQMD is the air pollution control agency for Orange County and major
portions of Los Angeles, San Bernardino and Riverside counties.
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