  The relationship between the pionium lifetime and the $\pi\pi$ scattering
lengths is established, including the sizable electromagnetic corrections. The
bound state formalism that is used is that of constraint theory which provides
a covariant three-dimensional reduction of the Bethe--Salpeter equation. The
framework of generalized chiral perturbation theory allows then an analysis of
the lifetime value as a function of the $\pi\pi$ scattering lengths, the latter
being dependent on the quark condensate value.
