Bacteria
 
Screen 2 of 2
They
are
 
in
 
the
air,
on
our
skin,
 
in
our
bodies,
 
 
in
 
the
ground,
 
and
all throughout
nature.
 
Most
bacteria
aren't
dangerous,
 
but
some
are
 
and
can
make
us
sick.