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Study: Air quality worst near freeways

Posted: September 10, 2008 10:24 p.m.
Updated: November 12, 2008 5:00 a.m.
When it comes to breathing in the Santa Clarita Valley, the most significant factor diminishing air quality and increasing the risk of cancer is microscopic cancer-causing chemicals released in the diesel emissions from trucks traveling along freeways.

A new report released this week by the South Coast Air Quality Management District found diesel exhaust was the key driver for air toxics risk, accounting for more than 80 percent of the total air toxics risk in the overall Southern California area sampled.

Between 1999 and 2005, the time period covered by the study, the cancer risk from air pollution declined an overall 8 percent throughout Southern California, the study said.

But scientific models generated by the study show air quality along Santa Clarita Valley's two major corridors - Interstate 5 and Highway 14 - is worse than in other local areas.

In areas where there is more truck traffic and in areas near ports - such as Long Beach, central Los Angeles and Riverside County - air quality levels were at their worst.

"The closer you are to the freeway, the closer you are to higher levels of tailpipe emissions," said Jean Ospital, health effects officer for the group that conducted the study.

When asked Wednesday what advice he had for Santa Clarita Valley residents who live near freeways, he replied, "We need to effectively focus on reducing air toxics and, in particular, diesel emissions.

"If we do this then we ought to see (particulate) levels come down."

The report is the third in an ongoing study of air quality with two other reports preceeding it - the first completed in 1986, followed by one in 1998.

The latest study - released as a draft in January and revised this year using improved computer modeling and emissions inventory methodologies - showed an overall decrease in the cancer risk from air pollution in the region from 931 in 1 million to 853 in 1 million from 1998-1999 to 2005.

While the region's overall risk decreased, the cancer risk from air pollution around the ports increased by about 17 percent from 1998 to 2005, in spite of ongoing cleanup efforts, due to the near-doubling of container shipments.

Slight increases were also seen in areas of Riverside County.

The increases are likely due to growth in trade at the ports and increased truck traffic and warehouse development in Riverside County.

"Cancer risks from air pollution are still far too high in the Southland," Barry Wallerstein, executive officer of the South Coast Air Quality Management District, said in a news release issued Tuesday.

"The study results show that we need to continue pursuing all feasible measures to reduce toxic emissions," Wallerstein said.

About 84 percent of all cancer risk from air pollution is due to diesel exhaust from trucks, trains, ships, locomotives and other diesel equipment.

The remaining risk is due to toxic emissions from gasoline-powered motor vehicles, businesses and industrial facilities.


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