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.
Continued…
Mesa Air Facts!