Marian Benjamin

Particulate matter was first recognized as a direct health issue because of radioactive fallout from above-ground nuclear tests worldwide.1 Technology led to improvements in air quality and to the ability to categorize particulate matter according to size: particulate matter with a diameter ≤10 µm but ≥2.5 µm (PM10), particulate matter with a diameter ≤2.5 µm but ≥0.1 µm (PM 2.5), and particles with a diameter ≤0.1 µm—ultrafine particle fraction (UFPs).2

The smaller the particle, the deeper it can penetrate into the lung cavity. Investigators overlooked the significant health impact of UFPs, however, until 1994, when researchers3 hypothesized that UFPs could cause toxicity to the human respiratory tract. Since that time, studies of children have demonstrated an association between UFP exposure and slower growth of lung function.4

Emissions from automobile and truck exhausts contain the insidious UFPs, and, in fact, “ultrafine particles are highest on and around freeways and … appear to have much higher levels of the damaging chemicals that are found to have health effects,” says Andre Nel, MBChB, PhD, California NanoSystems Institute, University of California, Los Angeles, Medical School.

Studies have shown that children living next to highways are more likely to develop respiratory diseases, such as asthma. Further, results of a study published in The Lancet5 found that children who grew up near freeways risk having their lung development impaired, which can increase the later possibility of serious respiratory disease. W. James Gauderman, PhD, and colleagues from the University of Southern California, Los Angeles, followed 3,677 children, age 10 years, for 8 years. At study’s end the researchers found that lung growth in children who lived within 500 meters of a freeway was significantly less than that of children who lived 1,500 meters or more from a freeway.

A MedLine search provided plenty of evidence that living, working, or going to school near a heavily trafficked freeway puts individuals at risk for lung disease or exacerbations of such. The evidence is strong enough that the State of California, in 2003, passed a law that prohibits school districts from building campuses within 500 feet (150 meters) of a freeway, unless the district can “mitigate the pollution.” Despite this law, the Los Angeles Unified School District (LAUSD) is planning to add five new schools that will be within 500 feet of freeways. A spokesperson for the school board president said she was concerned about children’s health, but would support the decision if the risks were mitigated. The school district has determined that air filtering would eliminate enough toxins to make the schools safe for children.

Editor’s note:
Search the RT archives for more articles about air pollution.

All well and good, but back to UFPs: They are so light and tiny that they are hard to capture or filter. According to a September 24 article in the Los Angeles Times,6 the district did not address these ultrafine particles that researchers believe cause the most harm.

The schools in question will be located in areas surrounded by freeways and plagued by poverty and low literacy rates—this is not a population likely to be aware of these studies or have any idea what UFPs are. It is shocking to me that the school district, to which children’s safety is entrusted, is prepared to put these young people in harm’s way.

For those of you who do not live in LA but do live in cities with freeways, interstate highways, or toll roads, find out whether your state has laws that prohibit building schools near a heavily trafficked roadway. Do some research. You might be as surprised as I was at what you find.

—Marian Benjamin
[email protected].


  1. Hughes JD. Pan’s Travail: Environmental Problems of the Ancient Greeks and Romans. Baltimore: Johns Hopkins University Press; 1996.
  2. Stradling D. Smokestacks and Progressives: Environmentalists, Engineers, and Air Quality in America, 1881-1951. Balitmore: Johns Hopkins University Press; 2002.
  3. Lalit BY. The relationship of the strontium-90 to caesium-137 activity ratio in milk to the rate of fallout from nuclear activity. Health Phys. 1974;27:565-69.
  4. Ibald-Mulli A, Wichmann HE, Kreyling W, Peters A. Epidemiological evidence on health effects of ultrafine particles. J Aerosol Med. 2002;15:189-201.
  5. Oberdorster G, Utell MJ. Ultrafine particles in the urban air: to the respiratory tract —and beyond? Environ Health Perspect. 2002;110(8):A440-1.
  6. Ultrafine particles. Effects. Available at: [removed][/removed]. Accessed September 27, 2007.
  7. Gauderman WJ, Vora H, McConell R, et al. Effect of exposure to traffic on lung development from 10 to 18 years of age: a cohort study. Lancet. 2007:369:571-7.
  8. Larrubia E. Schools still rise close to freeways. Los Angeles Times. September 24, 2007:1, 12.