Volcanoes
blast
more
than
100
million
tons
of
carbon
dioxide
into
the
atmosphere
every
year
but
the
gas
is
usually
____________________
.
When
a
volcano
erupts
,
carbon
dioxide
spreads
____________________
into
the
atmosphere
and
isn't
____________________
in
one
spot
.
But
sometimes
the
gas
gets
trapped
____________________
under
enormous
pressure
.
If
it
escapes
to
the
surface
in
a
dense
____________________
,
it
can
push
out
oxygen
-
rich
air
and
become
deadly
.
Huge
clouds
of
carbon
dioxide
____________________
released
from
California's
volcanic
Mammoth
Mountain
in
1984
,
____________________
thousands
of
trees
.
The
U
.
S
.
Forest
Service
declared
the
area
____________________
-
limits
to
campers
and
keeps
a
close
eye
on
gas
levels
there
to
____________________
day
.