What is the dune dust and what causes it?

The   dune   dust   plume   blows   up   onto   the   Nipomo   Mesa   from   the   off-highway   vehicle   park   on   the   Oceano   Dunes. The   dust   is   particulate   matter   (PM),   also   known   as   fine   particle   pollution.      One   misconception   is   that   the   dust   is caused   by   vehicle   tires   crushing   the   sand   grains.      This   makes   only   a   small   contribution   to   dust   particle   creation. Most   of   the   dust   is   caused   when   vehicle   tires   break   the   naturally   occurring   crust,   which   allows   the   loosened   sand grains   to   be   blown   across   the   surface   of   the   dunes   by   the   prevailing   on-shore   winds.      In   a   process   known   as saltation,   the   windblown   sand   grains   collide   with   each   other,   which   breaks   down   the   sand   grains   and   creates   fine dust   particles.      When   the   wind   is   high   enough,   the   fine   particles   are   picked   up   into   the   air   and   carried   inland   in   a dust plume that blows across the Nipomo Mesa and beyond.  The   saltation   process   and   resulting   dust   pollution   is   made   worse   by   the   loss   of   natural   vegetation   caused   by vehicle activity.  Dune vegetation slows down the surface winds and reduces saltation and dust emission.

What are the health threats from breathing dune dust?

Fine   particulate   matter   that   is   10   micrometers   (PM10)   or   less   in   size   is   classified   as   pollution   because   it   is   a   proven health   threat.      When   particulate   matter   is   inhaled,   it   is   trapped   in   the   lungs,   and   some   of   it   can   become   embedded in   the   lining   of   the   lung,   where   over   time   it   causes   scar   tissue   that   damages   lung   function.      The   effects   of   this   are cumulative.      The   more   PM   that   is   inhaled   the   more   the   lungs   are   affected.      The   smallest   particles   can   be   absorbed by   the   lungs   into   the   blood   stream   and   cause   heart   problems.      There   are   thousands   of   studies   linking   exposure   to particulate   matter   with   increased   risk   of   respiratory   and   cardiac   disease.      Inhaled   crystalline   silica   dust   is   known to cause lung cancer.   ( learn more… ) While   state   and   federal   authorities   have   set   maximum   PM   concentration   exposure   standards   to   protect   public health,   there   is   no      safe   level   of   exposure.      What   matters   is   how   much   PM   has   been   inhaled   over   time.      The   health risks   increase   with   the   cumulative   amount   of   PM   inhaled   in   a   person’s   lifetime.      Long-term   exposures   to   low   levels of   PM10   or   smaller   particles   and   short-term   exposures   to   higher   concentrations   can   both   have   serious   health effects.  

What level of dust emission is considered excessive?

The   California   Air   Resources   Board   (CARB)   has   established   standards   for   outdoor   exposure   to   PM10   and   PM2.5.     These are as follows: Annual Average 24 Hour Average PM10       20 µg/m3         50 µg/m3 PM2.5           12 µg/m3               none                 (µg stands for micrograms) In California, emissions greater than these are by law considered excessive. However,   these   standards   are   based   on   a   24-hour   average   and   thus   do   not   truly   reflect   the   health   risks   caused   by dune   dust   from   the   Oceano   SVRA.      On   the   Nipomo   Mesa,   PM   concentration   peaks   occur   when   people   are   most likely    to    be    active    outdoors    –    between    the    hours    of    10    a.m.    and    about    5    p.m.        During    these    hours,    PM10 concentrations   often   exceed   hundreds   of   µg/m3.         A   person   outdoors   at   this   time   can   receive   in   a   few   hours   many times   the   exposure   they   would   have   experienced   had   PM10   levels   been   a   constant   50   µg/m3   over   24   hours.     Remember, there really is no completely safe level of exposure.  

What can Nipomo Mesa people do to protect themselves?

People   who   live,   work   or   go   to   school   on   the   Nipomo   Mesa   can   protect   against   PM   exposure   by   avoiding   PM exposure   as   much   as   possible.   T his   means   avoiding   outdoor   activity   in   areas   affected   by   the   dust   pollution   during the   time   of   day   when   the   PM   concentrations   are   high.      People   can   monitor   the   air   quality   forecasts   on   the   Air Pollution   Control   District   and   EPA’s   AirNow   web   sites   (click   here   to   learn   more).      PM   concentrations   are   typically highest   between   10   a.m.   and   5   p.m.      Furthermore,   the   pollution   can   often   be   seen.   If   the   wind   is   blowing   and   you can actually see dust in the air, stay out of it.  Very   fine   particulate   matter   can   infiltrate   indoors.   Make   sure   window   and   door   seals   are   in   good   order   and windows   are   closed   during   high   wind   days.      Consider   using   high-performance   air   purifiers   for   the   places   in   your home   where   you   spend   most   of   your   time.      Running   central   air   fans   can   also   help   reduce   airborne   indoor   PM levels; high-efficiency return air filters work best.

From where is excessive dust being emitted?

Dune dust emissions that exceed State of California PM standards primarily come from the Oceano Dunes State Vehicle Recreation (SVRA) areas where off-highway vehicle activity is allowed.  Emissions often are greatest in the area known as the La Grande Tract, a 585-acre parcel within the off-highway vehicle park, in the northern part of the SVRA riding area. 
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Mesa Air Facts!

Concerned Citizens for Clean Air