from the Riverside Press-Enterprise Newspaper -- May 2, 2006
Tiny bits a big problemDeadliest pollution still unregulated
Andrew Silva, Staff writer
A whole new layer of regulations may be needed to deal with the tiniest and most dangerous bits of air pollution, as scientists released another study Monday showing children who live next to busy roads are twice as likely to have asthma symptoms.
"This is a major health issue," said John Froines, director of the Southern California Particle Center, during a conference in Los Angeles on ultrafine particles.
Ultrafine particles are unregulated, and are so small they can actually penetrate into cells, carrying toxic compounds right to a person's DNA and other critical areas.
As regulators struggle to scrub the air clean during a time of explosive growth in the diesel-powered shipping industry, scientists continue to warn that pollution from diesel sources is by far the most deadly. And the smaller the particle, the greater the danger.
"Ultrafines possess the greatest toxic potential compared to other particles," Froines said.
The South Coast Air Quality Management District will begin an in-depth examination of ultrafine particles in its next air quality management plan this year, said Barry Wallerstein, executive officer of the region's smog-fighting agency.
Regulations to control the toxic flecks of pollution are expected to follow in the next few years.
The study on asthma and roads, published this month in the journal "Environmental Health Perspectives," looked at more than 5,000 children, ages 5 to 7, who live in 13 Southern California communities .
It found those who live within about 80 yards of a major road are 50 percent more likely to have had asthma symptoms in the previous year than those who live farther away.
The study dovetails with previous research showing concentrations of ultrafine particles are greatest near roadways and drop off dramatically with distance.
"Ultrafines may be the cause" of respiratory problems, said Rob McConnell, one of the study's authors and a professor at USC.
Restrictions are in place for larger particles, those 10 microns in diameter, or PM10, which is about one-seventh the diameter of a human hair, and the smaller PM2.5. A micron is one-millionth of a meter, or about the thickness of a dime sliced 1,000 times.
The regulations may be having a strange side effect.
Reductions in larger particles may actually spur an increase in the number of ultrafine particles, scientists said.
"Little particles attach to larger particles," Froines said. If you lower the number of big particles, there are fewer for the small particles to glom onto, he said.
That phenomenon has scientists calling for a change in the way particulates are measured.
Currently, particles are regulated by their mass, which is to say the particles in a cubic meter of air are basically weighed.
Instead, the particles should be counted, which is now being done in Europe.
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