  The dynamical critical exponent $z$ is a fundamental quantity in
characterizing quantum criticality, and it is well known that the presence of
dissipation in a quantum model has significant impact on the value of $z$.
Studying quantum Ising spin models using Monte Carlo methods, we estimate the
dynamical critical exponent $z$ and the correlation length exponent $\nu$ for
different forms of dissipation. For a two-dimensional quantum Ising model with
Ohmic site dissipation, we find $z \approx 2$ as for the corresponding
one-dimensional case, whereas for a one-dimensional quantum Ising model with
Ohmic bond dissipation we obtain the estimate $z \approx 1$.
