diff --git a/cara/models.py b/cara/models.py
index d92d76e7..1561b09d 100644
--- a/cara/models.py
+++ b/cara/models.py
@@ -731,7 +731,7 @@ class ConcentrationModel:
         return self.infected.virus
 
     def infectious_virus_removal_rate(self, time: float) -> _VectorisedFloat:
-        # Particle deposition on the floor
+        # Particle deposition on the floor (value from CERN-OPEN-2021-04)
         vg = 1.88e-4
         # Height of the emission source to the floor - i.e. mouth/nose (m)
         h = 1.5