Comparison between the FWHM of the broad Balmer line as calculated in the present work (solid lines) with those calculated by van Adelsberg et al. (2008, dot-dashed lines). The dashed lines represent the FWHM calculated using our technique, but requiring that the partial distribution functions of broad neutrals are Maxwellian for k > 2, with the same temperature and the same bulk velocity as the ions. Dots show the FWHM calculated in the presence of CRs with acceleration efficiency equal to 0.1 and 0.2 and for shock speeds of 4000 and 6000 km s^-1.