diff --git a/caimira/apps/calculator/model_generator.py b/caimira/apps/calculator/model_generator.py
index 49fb639a..4896e485 100644
--- a/caimira/apps/calculator/model_generator.py
+++ b/caimira/apps/calculator/model_generator.py
@@ -807,7 +807,7 @@ def baseline_raw_form_data() -> typing.Dict[str, typing.Union[str, float]]:
 
 ACTIVITY_TYPES = {'office', 'smallmeeting', 'largemeeting', 'training', 'training_attendee', 'callcentre', 'controlroom-day', 'controlroom-night', 'library', 'workshop', 'lab', 'gym'}
 MECHANICAL_VENTILATION_TYPES = {'mech_type_air_changes', 'mech_type_air_supply', 'not-applicable'}
-MASK_TYPES = {'Type I', 'FFP2'}
+MASK_TYPES = {'Type I', 'FFP2', 'Cloth'}
 MASK_WEARING_OPTIONS = {'mask_on', 'mask_off'}
 VENTILATION_TYPES = {'natural_ventilation', 'mechanical_ventilation', 'no_ventilation'}
 VIRUS_TYPES = {'SARS_CoV_2', 'SARS_CoV_2_ALPHA', 'SARS_CoV_2_BETA','SARS_CoV_2_GAMMA', 'SARS_CoV_2_DELTA', 'SARS_CoV_2_OMICRON'}
diff --git a/caimira/apps/static/images/masks/cloth.png b/caimira/apps/static/images/masks/cloth.png
new file mode 100644
index 00000000..40481b68
Binary files /dev/null and b/caimira/apps/static/images/masks/cloth.png differ
diff --git a/caimira/apps/templates/base/calculator.form.html.j2 b/caimira/apps/templates/base/calculator.form.html.j2
index b1dc9534..665527f6 100644
--- a/caimira/apps/templates/base/calculator.form.html.j2
+++ b/caimira/apps/templates/base/calculator.form.html.j2
@@ -295,6 +295,13 @@
             </label>
         </div>
       </div>
+      <div>
+        <input type="radio" id="mask_type_cloth"  name="mask_type" value="Cloth" onclick="require_fields(this)">
+          <label for="mask_type_cloth">
+            Cloth
+            <img class="mask_icons" src="/static/images/masks/cloth.png">
+          </label>
+      </div>
     </div>
     <hr width="80%">
 
diff --git a/caimira/models.py b/caimira/models.py
index 86808236..4a96be97 100644
--- a/caimira/models.py
+++ b/caimira/models.py
@@ -526,6 +526,9 @@ class Mask:
     #: Filtration efficiency of masks when inhaling.
     η_inhale: _VectorisedFloat
 
+    #: Filtration efficiency of masks when exhaling.
+    η_exhale: typing.Union[None, _VectorisedFloat] = None
+
     #: Global factor applied to filtration efficiency of masks when exhaling.
     factor_exhale: float = 1.
 
@@ -541,6 +544,10 @@ class Mask:
         the leakage through the sides.
         Diameter is in microns.
         """
+        if self.η_exhale is not None:
+            # When η_exhale is specified, return it directly
+            return self.η_exhale
+        
         d = np.array(diameter)
         intermediate_range1 = np.bitwise_and(0.5 <= d, d < 0.94614)
         intermediate_range2 = np.bitwise_and(0.94614 <= d, d < 3.)
@@ -570,6 +577,10 @@ Mask.types = {
     'FFP2': Mask(
         η_inhale=0.865,  # (94% penetration efficiency + 8% max inward leakage -> EN 149)
     ),
+    'Cloth': Mask(  # https://doi.org/10.1080/02786826.2021.1890687
+        η_inhale=0.225,
+        η_exhale=0.35,
+    ),
 }
 
 
diff --git a/caimira/monte_carlo/data.py b/caimira/monte_carlo/data.py
index 8ad2fcfc..e0eaa09a 100644
--- a/caimira/monte_carlo/data.py
+++ b/caimira/monte_carlo/data.py
@@ -167,9 +167,11 @@ virus_distributions = {
 # https://doi.org/10.1080/02786826.2021.1890687
 # https://doi.org/10.1016/j.jhin.2013.02.007
 # https://doi.org/10.4209/aaqr.2020.08.0531
+# https://doi.org/10.1080/02786826.2021.1890687
 mask_distributions = {
-    'Type I': mc.Mask(Uniform(0.25, 0.80)),
-    'FFP2': mc.Mask(Uniform(0.83, 0.91)),
+    'Type I': mc.Mask(η_inhale=Uniform(0.25, 0.80)),
+    'FFP2': mc.Mask(η_inhale=Uniform(0.83, 0.91)),
+    'Cloth': mc.Mask(η_inhale=Uniform(0.05, 0.40), η_exhale=Uniform(0.20, 0.50)),
 }
 
 
diff --git a/caimira/tests/apps/calculator/test_model_generator.py b/caimira/tests/apps/calculator/test_model_generator.py
index 1dbb4961..787e7a8e 100644
--- a/caimira/tests/apps/calculator/test_model_generator.py
+++ b/caimira/tests/apps/calculator/test_model_generator.py
@@ -30,6 +30,7 @@ def test_model_from_dict_invalid(baseline_form_data):
     [
         ["No mask"],
         ["Type I"],
+        ["Cloth"],
     ]
 )
 def test_blend_expiration(mask_type):
diff --git a/caimira/tests/test_monte_carlo_full_models.py b/caimira/tests/test_monte_carlo_full_models.py
index 0e333526..9ce540e0 100644
--- a/caimira/tests/test_monte_carlo_full_models.py
+++ b/caimira/tests/test_monte_carlo_full_models.py
@@ -347,6 +347,8 @@ def test_report_models(mc_model, expected_pi, expected_new_cases,
         ["Type I",  "Jul", 1.663, 0.938, 193.52],
         ["FFP2",    "Jul", 0.523, 0.253, 193.52],
         ["Type I",  "Feb", 0.659, 0.325, 193.52],
+        ["Cloth",   "Feb", 2.653, 1.741, 673.10],
+        ["Cloth",   "Jul", 5.322, 5.064, 673.10],
     ],
 )
 def test_small_shared_office_Geneva(mask_type, month, expected_pi,