  We have observed 10 interacting galaxy pairs using the Fabry-Perot
interferometer GH$\alpha$FaS (Galaxy H$\alpha$ Fabry-Perot system) on the
$4.2\rm{m}$ William Herschel Telescope (WHT) at the Observatorio del Roque de
los Muchachos, La Palma. We present here the H$\alpha$ surface brightness,
velocity and velocity dispersion maps for the 10 systems we have not previously
observed using this technique, as well as the physical properties (sizes,
H$\alpha$ luminosities and velocity dispersion) of 1259 HII regions from the
full sample. We also derive the physical properties of 1054 HII regions in a
sample of 28 isolated galaxies observed with the same instrument in order to
compare the two populations of HII regions. We find a population of the
brightest HII regions for which the scaling relations, for example the relation
between the H$\alpha$ luminosity and the radius, are clearly distinct from the
relations for the regions of lower luminosity. The regions in this bright
population are more frequent in the interacting galaxies. We find that the
turbulence, and also the star formation rate, are enhanced in the HII regions
in the interacting galaxies. We have also extracted the H$\alpha$ equivalent
widths for the HII regions of both samples, and we have found that the
distribution of HII region ages coincides for the two samples of galaxies. We
suggest that the SFR enhancement is brought about by gas flows induced by the
interactions, which give rise to gravitationally bound gas clouds which grow
further by accretion from the flowing gas, producing conditions favourable to
star formation.
