diff --git a/tardis/transport/montecarlo/base.py b/tardis/transport/montecarlo/base.py
index 6638f43e917..5662a6be9c8 100644
--- a/tardis/transport/montecarlo/base.py
+++ b/tardis/transport/montecarlo/base.py
@@ -110,9 +110,10 @@ def initialize_transport_state(
             self.line_interaction_type,
             self.montecarlo_configuration.DISABLE_LINE_SCATTERING,
         )
-        opacity_state = opacity_state[
-            simulation_state.geometry.v_inner_boundary_index : simulation_state.geometry.v_outer_boundary_index
-        ]
+        opacity_state = opacity_state.slice(
+            simulation_state.geometry.v_inner_boundary_index,
+            simulation_state.geometry.v_outer_boundary_index
+        )
         estimators = initialize_estimator_statistics(
             opacity_state.tau_sobolev.shape, gamma_shape
         )
diff --git a/tardis/transport/montecarlo/numba_interface.py b/tardis/transport/montecarlo/numba_interface.py
index 7499f8fdb3f..2496f230520 100644
--- a/tardis/transport/montecarlo/numba_interface.py
+++ b/tardis/transport/montecarlo/numba_interface.py
@@ -119,8 +119,9 @@ def __getitem__(self, i):
             i (int, slice): shell index or slice
 
         Returns:
-            OpacityState a shallow copy of the current instance
+            OpacityState : a shallow copy of the current instance
         """
+        #NOTE: This currently will not work with continuum processes since it does not slice those arrays
         return OpacityState(
             self.electron_density[i],
             self.t_electrons[i],
@@ -146,6 +147,40 @@ def __getitem__(self, i):
             self.k_packet_idx,
         )
 
+    def slice(self, i):
+        """Get a shell or slice of shells of the attributes of the opacity state
+
+        Args:
+            i (int, slice): shell index or slice
+
+        Returns:
+            OpacityState : a shallow copy of the current instance
+        """
+        #NOTE: This currently will not work with continuum processes since it does not slice those arrays
+        return OpacityState(
+            self.electron_density[i],
+            self.t_electrons[i],
+            self.line_list_nu,
+            self.tau_sobolev[:, i],
+            self.transition_probabilities[:, i],
+            self.line2macro_level_upper,
+            self.macro_block_references,
+            self.transition_type,
+            self.destination_level_id,
+            self.transition_line_id,
+            self.bf_threshold_list_nu,
+            self.p_fb_deactivation,
+            self.photo_ion_nu_threshold_mins,
+            self.photo_ion_nu_threshold_maxs,
+            self.photo_ion_block_references,
+            self.chi_bf,
+            self.x_sect,
+            self.phot_nus,
+            self.ff_opacity_factor,
+            self.emissivities,
+            self.photo_ion_activation_idx,
+            self.k_packet_idx,
+        )
 
 def opacity_state_initialize(
     plasma,
diff --git a/tardis/transport/montecarlo/tests/test_numba_interface.py b/tardis/transport/montecarlo/tests/test_numba_interface.py
index 25d907049f6..10830cb1463 100644
--- a/tardis/transport/montecarlo/tests/test_numba_interface.py
+++ b/tardis/transport/montecarlo/tests/test_numba_interface.py
@@ -4,8 +4,9 @@
 import numpy as np
 
 
-@pytest.mark.parametrize("input_params", ["scatter", "macroatom", "downbranch"])
-def test_opacity_state_initialize(nb_simulation_verysimple, input_params):
+
+@pytest.mark.parametrize("input_params,sliced", [("scatter", False), ("macroatom", False), ("macroatom", True), ("downbranch", False), ("downbranch", True)])
+def test_opacity_state_initialize(nb_simulation_verysimple, input_params, sliced):
     line_interaction_type = input_params
     plasma = nb_simulation_verysimple.plasma
     actual = numba_interface.opacity_state_initialize(
@@ -13,12 +14,19 @@ def test_opacity_state_initialize(nb_simulation_verysimple, input_params):
         line_interaction_type,
         disable_line_scattering=False,
     )
+    print(dir(actual))
+    if sliced:
+        index = slice(2, 5)
+        actual = actual.slice(index)
+    else:
+        index = ...
 
     npt.assert_allclose(
-        actual.electron_density, plasma.electron_densities.values
+        actual.electron_density, plasma.electron_densities.values[index]
     )
     npt.assert_allclose(actual.line_list_nu, plasma.atomic_data.lines.nu.values)
-    npt.assert_allclose(actual.tau_sobolev, plasma.tau_sobolevs.values)
+    print(actual.tau_sobolev.shape,  plasma.tau_sobolevs.values[:, index].shape)
+    npt.assert_allclose(actual.tau_sobolev, plasma.tau_sobolevs.values[:, index])
     if line_interaction_type == "scatter":
         empty = np.zeros(1, dtype=np.int64)
         npt.assert_allclose(
@@ -32,7 +40,7 @@ def test_opacity_state_initialize(nb_simulation_verysimple, input_params):
     else:
         npt.assert_allclose(
             actual.transition_probabilities,
-            plasma.transition_probabilities.values,
+            plasma.transition_probabilities.values[:, index],
         )
         npt.assert_allclose(
             actual.line2macro_level_upper,