South County (San Luis Obispo) Phase 2 Particulate Study

The San Luis Obispo Air Control Board released a study on February 22, 2010 regarding the impacts of off-road vehicle use at the Oceano Dunes and the resultant air pollution at the nearby Nipomo Mesa.  The study was initially slated for release in December 2009, but was postponed until this week.

A preliminary study was originally undertaken in 2004 to determine what was causing high levels of air pollution at the Nipomo Mesa – causing potentially significant health problems for the people in this community.   That study was somewhat inconclusive on certain points.  Thus a second phase was begun in 2008 and completed in 2009 to hone in on the source of the pollution, with two primary targets – a ConocoPhillips refinery and the Oceano Dunes State Vehicle Recreational Area.  It turns out the refinery was completely exonerated in the study, while the ORV area was fully implicated.

Here’s the crux excerpt from the Executive Summary:

The 3-pronged field investigation effort for the Phase 2 study gathered well over two million data points, requiring nearly a year to review, validate and analyze the data and compile the results. The data analysis was performed by the three independent research groups involved in designing and implementing the study, followed by peer review of the draft study report by a diverse and respected group of scientists with expertise in this field. This wealth of data and critical review of the results by numerous independent experts, combined with the results from the Phase 1 study, provides a much more complete understanding of the particulate pollution problem in the area, leading to the following major findings:

• The airborne particulate matter predominantly impacting the region on high episode days does not originate from an offshore source.
• Neither the petroleum coke piles at the ConocoPhillips facility nor agricultural fields or activities in and around the area are a significant source of ambient PM on the Nipomo Mesa.
• The airborne particulate matter impacting the Nipomo Mesa on high episode days predominantly consists of fine sand material transported to the Mesa from upwind areas under high wind conditions.
• The primary source of high PM levels measured on the Nipomo Mesa is the open sand sheets in the dune areas of the coast.
• The open sand sheets subject to OHV activity on the SVRA emit significantly greater amounts of particulates than the undisturbed sand sheets at the study control sites under the same wind conditions.
• Vegetated dune areas do not emit wind blown particles; the control site dunes have significantly higher vegetation coverage than is present at the SVRA.

The major findings resulting from detailed analysis of the diverse and comprehensive data sets generated during the Phase 1 and Phase 2 South County PM Studies clearly lead to a definitive conclusion: OHV activity in the SVRA is a major contributing factor to the high PM concentrations observed on the Nipomo Mesa.

 For the full report, click on the link to the San Luis Obispo Air Pollution Control District website to the right, or click on the attachment, below.