diff --git a/cara/models.py b/cara/models.py
index ec81b37c..291dcfc1 100644
--- a/cara/models.py
+++ b/cara/models.py
@@ -526,8 +526,8 @@ Expiration.types = {
 
 @dataclass(frozen=True)
 class Activity:
-    inhalation_rate: float
-    exhalation_rate: float
+    inhalation_rate: _VectorisedFloat
+    exhalation_rate: _VectorisedFloat
 
     #: Pre-populated examples of activities.
     types: typing.ClassVar[typing.Dict[str, "Activity"]]
diff --git a/cara/tests/models/test_exposure_model.py b/cara/tests/models/test_exposure_model.py
index 34ed03af..464f25a9 100644
--- a/cara/tests/models/test_exposure_model.py
+++ b/cara/tests/models/test_exposure_model.py
@@ -46,20 +46,37 @@ populations = [
         10, halftime, models.Mask(0.95, 0.15, np.array([0.3, 0.35])),
         models.Activity.types['Standing'],
     ),
+    # A population with some array component for inhalation_rate.
+    models.Population(
+        10, halftime, models.Mask.types['Type I'],
+        models.Activity(np.array([0.51,0.57]), 0.57),
+    ),
 ]
 
 
 @pytest.mark.parametrize(
-    "population, cm, expected_exposure",[
-    [populations[1], KnownConcentrations(lambda t: 1.2), np.array([14.4, 14.4])],
-    [populations[0], KnownConcentrations(lambda t: np.array([1.2, 2.4])), np.array([14.4, 28.8])],
-    [populations[1], KnownConcentrations(lambda t: np.array([1.2, 2.4])), np.array([14.4, 28.8])],
+    "population, cm, expected_exposure, expected_probability",[
+    [populations[1], KnownConcentrations(lambda t: 1.2),
+     np.array([14.4, 14.4]), np.array([99.6803184113, 99.5181053773])],
+
+    [populations[2], KnownConcentrations(lambda t: 1.2),
+     np.array([14.4, 14.4]), np.array([99.4146994564, 99.6803184113])],
+
+    [populations[0], KnownConcentrations(lambda t: np.array([1.2, 2.4])),
+     np.array([14.4, 28.8]), np.array([99.6803184113, 99.9989780368])],
+
+    [populations[1], KnownConcentrations(lambda t: np.array([1.2, 2.4])),
+     np.array([14.4, 28.8]), np.array([99.6803184113, 99.9976777757])],
     ])
-def test_exposure_model_ndarray(population, cm, expected_exposure):
+def test_exposure_model_ndarray(population, cm, 
+                                expected_exposure, expected_probability):
     model = ExposureModel(cm, population)
     np.testing.assert_almost_equal(
         model.quanta_exposure(), expected_exposure
     )
+    np.testing.assert_almost_equal(
+        model.infection_probability(), expected_probability, decimal=10
+    )
 
     assert isinstance(model.infection_probability(), np.ndarray)
     assert isinstance(model.expected_new_cases(), np.ndarray)
diff --git a/cara/tests/test_infected_population.py b/cara/tests/test_infected_population.py
index ab9e36d3..39fbc039 100644
--- a/cara/tests/test_infected_population.py
+++ b/cara/tests/test_infected_population.py
@@ -3,13 +3,14 @@ import pytest
 
 import cara.models
 
+
 @pytest.mark.parametrize(
     "override_params", [
         {'viral_load_in_sputum': np.array([5e8, 1e9])},
         {'coefficient_of_infectivity': np.array([0.02, 0.05])},
         {'η_exhale': np.array([0.92, 0.95])},
         {'η_leaks': np.array([0.15, 0.20])},
-
+        {'exhalation_rate': np.array([0.75, 0.81])},
     ]
 )
 def test_infected_population_vectorisation(override_params):
@@ -19,6 +20,7 @@ def test_infected_population_vectorisation(override_params):
         'coefficient_of_infectivity': 0.02,
         'η_exhale': 0.95,
         'η_leaks': 0.15,
+        'exhalation_rate': 0.75,
     }
     defaults.update(override_params)
 
@@ -33,7 +35,7 @@ def test_infected_population_vectorisation(override_params):
             ),
             activity=cara.models.Activity(
                 0.51,
-                0.75,
+                defaults['exhalation_rate'],
             ),
             virus=cara.models.Virus(
                 halflife=defaults['virus_halflife'],