  We calculate the rate for pair production of light pseudoscalars by strong
inhomogeneous and static electric (magnetic) fields. We show that, in the case
of axions, the stability of atoms over cosmic lifetimes is jeopardised unless
the Peccei-Quinn symmetry breaking scale $f_a$ is larger than ${\cal O}
(10^{10} GeV)$.

High Energy Physics - Phenomenology