diff --git a/pyaerocom/data/variables.ini b/pyaerocom/data/variables.ini
index c0e357240..0aeff2aa9 100644
--- a/pyaerocom/data/variables.ini
+++ b/pyaerocom/data/variables.ini
@@ -3098,11 +3098,11 @@ description=Mass concentration of ozone
 unit = ug m-3
 
 [conco3mda8]
-description=MDA8 of O3 mass concentration
+description= Daily maximum of the 8 hour rolling mean (see EU Directive 2008/50/EC Annex XI) of O3 mass concentration.
 unit = ug m-3
 
 [vmro3mda8]
-description=MDA8 of O3 VMR.
+description=Daily maximum of the 8 hour rolling mean (see EU Directive 2008/50/EC Annex XI) of O3 volume mixing ratio.
 unit = nmol mol-1
 
 [concco]