State commission looking into the origin of dust on the Nipomo Mesa

December 8, 2021


At a special meeting on Thursday, a scientist with the Scripps Institute of Oceanography will explain her investigation and findings into the origin and composition of airborne particulate matter (PM10) collected on the Nipomo Mesa.

Since 2007, the San Luis Obispo County Air Pollution Control District (APCD) has consistently maintained that high PM10 concentrations detected during high wind days on the Nipomo Mesa were comprised of windblown mineral dust from the Oceano Dunes.

However, the APCD did not test the PM10 for mineral dust until 2020, after Scripps had done so, according to the commission’s website. That APCD data has not been made public.

In her report, atmospheric chemist Dr. Lynn Russell discovered that during the windiest days of the year, when the winds are blowing from the west and PM10 readings on the Nipomo Mesa are high, the amount of mineral dust in the PM10 is on average 14% and not the 100% the APCD claims.

“The primary purpose of this investigation, which is part of a larger three-year study, is to quantify that portion of measured PM that consists of mineral dust,” Russell says in her report. “Mineral dust is generated from the windblown sand dune building process called saltation, and so quantifying the mineral dust portion of PM at the (APCD air quality monitoring station on the Nipomo Mesa) provides a conservative measure of that portion of PM on the Mesa that could possibly be from the Oceano Dunes State Vehicle Recreation Area (SVRA). The mineral dust measure is conservative because saltation occurs in the dunes inside and outside the SVRA, and mineral dust is also derived from agricultural operations and vehicles driving on dirt roads—activities that occur in the region that lies between the SVRA and the Mesa.”

Though the APCD’s 2020 testing for mineral dust in PM10 has not been made public, Russell was able to review the analytical results from that testing. Russell found APCD’s 2020 testing supported the findings of her investigation.

Watch the commission meeting at 9 a.m on Thursday at Cal-Span. Find information on how to participate here.


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All you have to do is go to the cliffs near Shell Beach. On a clear and usually windy day, you can see that haze of dust over the dunes. That has gone on for thousands of years. It has nothing to do with off road vehicles. I anyone is silly enough to build houses downwind of the dunes, that’s simply your fault. I used to live in an RV park in Oceano (Pacific Dunes). The wind and dust was almost constant except after a heavy rain. It literally comes with the territory.

Adam Trask

Isn’t it ironic that many of those who are applauding the Scripps Institute’s study on the Nipomo Dunes would turn around and deny the same institute’s conclusions on climate change. Scripps has consistently warned that global warming and the continued burning of fossil fuels (as ATV’s do) pose an existential threat to the survival of humans.


I’ve been visiting the dunes for over 50 years ….The dunes change shape overnight sometimes if there is high winds .The dunes constantly change shape ….The large clouds seen all over the central valley sky are Dust clouds from winds .There is not a giant off road facility covering the entire central valley . If a person does not want sand in the air or in their house they should not live near a beach .Same as the case of not wanting dirt in the air or in their house in central valley they should not live their either …they would be much happier in a damp forest that has no dust or flying sand ….but then they’d complain about forest fires


I have two solutions to this problem and they will be 100% effective. 1. pave the whole beach. or 2. stop the wind. Now where do I pick up my check?


I have a better solution: keep studying the problem forever while effectively doing nothing.