  A new mechanisms for damping of slow magnetosonic waves (SMW) by pressure
induced oscillations of the ionization degree is proposed. An explicit formula
for the damping rate is quantitatively derived. Physical conditions where the
new mechanism will dominate are briefly discussed. The ionization-recombination
damping is frequency independent and has no hydrodynamic interpretation.
Roughly speaking large area of partially ionized plasma are damper for basses
of SMW while usual MHD mechanisms operate as a low pass filter. The derived
damping rate is proportional to the square of the sine between the constant
magnetic field and the wave-vector. Angular distribution of the spectral
density of SMW and Alfv\'en waves (AW) created by turbulent regions and passing
through large regions of partially ionized plasma is qualitatively considered.
The calculated damping rate is expressed by the electron impact cross section
of the hydrogen atom and in short all details of the proposed damping
mechanisms are well studied.
