  We study Birkhoff-James orthogonality and its pointwise symmetry in
commutative $C^*$ algebras, i.e., the space of all continuous functions defined
on a locally compact Hausdorff space that vanish at infinity. We use this
characterization to obtain the characterization of Birkhoff-James orthogonality
on $L_\infty$ space defined on any arbitrary measure space. We also do the same
for the $L_p$ spaces for $1\leq p<\infty$.
