  Recent pulsar scintillation measurements from Ooty, in conjunction with those
from Parkes and other large radio telescopes, are used for a systematic
investigation of the Local Interstellar Medium (LISM) towards the general
direction of the Loop I Bubble. For several pulsars, clear evidence is found
for an enhanced level of scattering which is over and above what can be
accounted for by the enhanced scattering model for the Local Bubble. These
results are interpreted in terms of enhanced scattering due to turbulent plasma
associated with the Loop I shell. Useful constraints are obtained for the
scattering properties of the shell. The inferred value for the scattering
measure for the Loop I shell is found to be ~0.3 pc m^{-20/3}. Assuming a shell
thickness ~5-10 pc, this implies an average strength of scattering in the shell
that is ~100-200 times larger than that in the ambient ISM. An alternative
explanation, where the enhanced level of scattering is due to a possible
"interaction zone" between the Local Bubble and the Loop I Bubble, is also
considered; it is found to be somewhat less satisfactory in explaining the
observations. The best fit value for the scattering measure for such an
interaction zone region is estimated to be ~1.1 pc m^{-20/3}.
  Further, several pulsars beyond ~1 kpc are found to show enhanced levels of
scattering over and above that expected from this "two-bubble model." For some
of the low-latitude pulsars, this is found to be due to enhanced scattering
from plasma inside the intervening Sagittarius spiral arm. We discuss the
implications of our results for the interpretation of scintillation data and
for the general understanding of the LISM.
