diff --git a/mlair/data_handler/data_handler_single_station.py b/mlair/data_handler/data_handler_single_station.py
index e554a3b32d8e4e2f5482a388374cfba87f7add15..8131566acb9d5456832770152d8776fa6827d6f4 100644
--- a/mlair/data_handler/data_handler_single_station.py
+++ b/mlair/data_handler/data_handler_single_station.py
@@ -271,7 +271,7 @@ class DataHandlerSingleStation(AbstractDataHandler):
         chem_vars = ["benzene", "ch4", "co", "ethane", "no", "no2", "nox", "o3", "ox", "pm1", "pm10", "pm2p5",
                      "propane", "so2", "toluene"]
         # used_chem_vars = list(set(chem_vars) & set(self.statistics_per_var.keys()))
-        used_chem_vars = list(set(chem_vars) & set(self.variables))
+        used_chem_vars = list(set(chem_vars) & set(data.variables.values))
         data.loc[..., used_chem_vars] = data.loc[..., used_chem_vars].clip(min=minimum)
         return data