diff --git a/src/data_generator.py b/src/data_generator.py
index dcd02bdd9530901026176df6de533ac0c3e84114..860791235f111a7ffb151f2b06424be76dc8eba7 100644
--- a/src/data_generator.py
+++ b/src/data_generator.py
@@ -42,7 +42,7 @@ class DataGenerator(keras.utils.Sequence):
         display all class attributes
         """
         return f"DataGenerator(path='{self.data_path}', network='{self.network}', stations={self.stations}, " \
-               f"variables={self.variables}, station_type='{self.station_type}', " \
+               f"variables={self.variables}, station_type={self.station_type}, " \
                f"interpolate_dim='{self.interpolate_dim}', target_dim='{self.target_dim}', " \
                f"target_var='{self.target_var}', **{self.kwargs})"
 
diff --git a/src/data_preparation.py b/src/data_preparation.py
index 061eddc453fc6f2a8802f0b6cce0a1b0b7893e0d..3cadf590778e39174f76a139514fed5d8cbc505f 100644
--- a/src/data_preparation.py
+++ b/src/data_preparation.py
@@ -89,9 +89,11 @@ class DataPrep(object):
             self.data = self.check_for_negative_concentrations(data)
 
     def check_station_type(self):
+        """
+        Search for the `station_type` entry in meta data and compare the value with the requested station_type. Raise
+        an EmptyQueryResult error if the values mismatch.
+        """
         if self.meta.at["station_type", self.station[0]] != self.station_type:
-            self.data = None
-            self.meta = None
             raise join.EmptyQueryResult
 
     def download_data_from_join(self, file_name: str, meta_file: str) -> [xr.DataArray, pd.DataFrame]:
diff --git a/test/test_data_generator.py b/test/test_data_generator.py
index 7c745782bc057060dd439af1fb6e03c5b3ef5730..39a352327b7e3f5eb4f9b046a52aa763372df61c 100644
--- a/test/test_data_generator.py
+++ b/test/test_data_generator.py
@@ -21,6 +21,7 @@ class TestDataGenerator:
         assert gen.network == 'UBA'
         assert gen.stations == ['DEBW107']
         assert gen.variables == ['o3', 'temp']
+        assert gen.station_type is None
         assert gen.interpolate_dim == 'datetime'
         assert gen.target_dim == 'variables'
         assert gen.target_var == 'o3'
@@ -34,7 +35,7 @@ class TestDataGenerator:
     def test_repr(self, gen):
         path = os.path.join(os.path.dirname(__file__), 'data')
         assert gen.__repr__().rstrip() == f"DataGenerator(path='{path}', network='UBA', stations=['DEBW107'], "\
-                                          f"variables=['o3', 'temp'], interpolate_dim='datetime', " \
+                                          f"variables=['o3', 'temp'], station_type=None, interpolate_dim='datetime', " \
                                           f"target_dim='variables', target_var='o3', **{{}})".rstrip()
 
     def test_len(self, gen):
diff --git a/test/test_data_preparation.py b/test/test_data_preparation.py
index 5d45c041b6e669cced56172d41fc2f9653dd30e7..0a520eafc40e6bdd31ed2738488af1292fc00f59 100644
--- a/test/test_data_preparation.py
+++ b/test/test_data_preparation.py
@@ -22,7 +22,7 @@ class TestDataPrep:
         assert data.station == ['DEBW107']
         assert data.variables == ['o3', 'temp']
         assert data.statistics_per_var == {'o3': 'dma8eu', 'temp': 'maximum'}
-        assert not all([data.mean, data.std, data.history, data.label])
+        assert not all([data.mean, data.std, data.history, data.label, data.station_type])
         assert {'test': 'testKWARGS'}.items() <= data.kwargs.items()
 
     def test_init_no_stats(self):
@@ -35,9 +35,10 @@ class TestDataPrep:
         d.network = 'dummy'
         d.station = ['DEBW107']
         d.variables = ['o3', 'temp']
+        d.station_type = "traffic"
         d.kwargs = None
         assert d.__repr__().rstrip() == "Dataprep(path='data/test', network='dummy', station=['DEBW107'], "\
-                                        "variables=['o3', 'temp'], **None)".rstrip()
+                                        "variables=['o3', 'temp'], station_type='traffic', **None)".rstrip()
 
     def test_set_file_name_and_meta(self):
         d = object.__new__(DataPrep)
diff --git a/test/test_modules/test_experiment_setup.py b/test/test_modules/test_experiment_setup.py
index 832ff45a0a3b1384e1300c0fa38ed3d1ec2204b8..be3db59e2415f28ea63d42b7cc6ced6b2c095700 100644
--- a/test/test_modules/test_experiment_setup.py
+++ b/test/test_modules/test_experiment_setup.py
@@ -48,7 +48,7 @@ class TestExperimentSetup:
         # experiment setup
         assert data_store.get("data_path", "general") == prepare_host()
         assert data_store.get("trainable", "general") is False
-        assert data_store.get("fraction_of_train", "general") == 0.8
+        assert data_store.get("fraction_of_training", "general") == 0.8
         # set experiment name
         assert data_store.get("experiment_name", "general") == "TestExperiment"
         path = os.path.abspath(os.path.join(os.path.dirname(__file__), "..", "..", "TestExperiment"))
@@ -67,6 +67,7 @@ class TestExperimentSetup:
                             'DEBW052', 'DEBW034', 'DEBY088', ]
         assert data_store.get("stations", "general") == default_stations
         assert data_store.get("network", "general") == "AIRBASE"
+        assert data_store.get("station_type", "general") is None
         assert data_store.get("variables", "general") == list(default_var_all_dict.keys())
         assert data_store.get("statistics_per_var", "general") == default_var_all_dict
         assert data_store.get("start", "general") == "1997-01-01"
@@ -97,7 +98,8 @@ class TestExperimentSetup:
         experiment_path = os.path.abspath(os.path.join(os.path.dirname(__file__), "..", "data", "testExperimentFolder"))
         kwargs = dict(parser_args={"experiment_date": "TODAY"},
                       var_all_dict={'o3': 'dma8eu', 'relhum': 'average_values', 'temp': 'maximum'},
-                      stations=['DEBY053', 'DEBW059', 'DEBW027'], network="INTERNET", variables=["o3", "temp"],
+                      stations=['DEBY053', 'DEBW059', 'DEBW027'], network="INTERNET", station_type="background",
+                      variables=["o3", "temp"],
                       statistics_per_var=None, start="1999-01-01", end="2001-01-01", window_history=4,
                       target_var="temp", target_dim="target", window_lead_time=10, dimensions="dim1",
                       interpolate_dim="int_dim", interpolate_method="cubic", limit_nan_fill=5, train_start="2000-01-01",
@@ -109,7 +111,7 @@ class TestExperimentSetup:
         # experiment setup
         assert data_store.get("data_path", "general") == prepare_host()
         assert data_store.get("trainable", "general") is True
-        assert data_store.get("fraction_of_train", "general") == 0.5
+        assert data_store.get("fraction_of_training", "general") == 0.5
         # set experiment name
         assert data_store.get("experiment_name", "general") == "TODAY_network/"
         path = os.path.abspath(os.path.join(os.path.dirname(__file__), "..", "data", "testExperimentFolder"))
@@ -119,6 +121,7 @@ class TestExperimentSetup:
                                                              'temp': 'maximum'}
         assert data_store.get("stations", "general") == ['DEBY053', 'DEBW059', 'DEBW027']
         assert data_store.get("network", "general") == "INTERNET"
+        assert data_store.get("station_type", "general") == "background"
         assert data_store.get("variables", "general") == ["o3", "temp"]
         assert data_store.get("statistics_per_var", "general") == {'o3': 'dma8eu', 'relhum': 'average_values',
                                                                    'temp': 'maximum'}
diff --git a/test/test_modules/test_pre_processing.py b/test/test_modules/test_pre_processing.py
index bc121885ddb8ee20b0f571e7f0250845c6e99e6a..eb7ba4e8f4d909711f92ca667b98ae403cb30756 100644
--- a/test/test_modules/test_pre_processing.py
+++ b/test/test_modules/test_pre_processing.py
@@ -1,7 +1,7 @@
 import logging
 import pytest
 
-from src.helpers import PyTestRegex, TimeTracking
+from src.helpers import PyTestRegex
 from src.modules.experiment_setup import ExperimentSetup
 from src.modules.pre_processing import PreProcessing, DEFAULT_ARGS_LIST, DEFAULT_KWARGS_LIST
 from src.data_generator import DataGenerator
@@ -29,8 +29,8 @@ class TestPreProcessing:
 
     @pytest.fixture
     def obj_with_exp_setup(self):
-        ExperimentSetup(parser_args={}, stations=['DEBW107', 'DEBY081', 'DEBW013', 'DEBW076', 'DEBW087'],
-                        var_all_dict={'o3': 'dma8eu', 'temp': 'maximum'})
+        ExperimentSetup(parser_args={}, stations=['DEBW107', 'DEBY081', 'DEBW013', 'DEBW076', 'DEBW087', 'DEBW001'],
+                        var_all_dict={'o3': 'dma8eu', 'temp': 'maximum'}, station_type="background")
         pre = object.__new__(PreProcessing)
         super(PreProcessing, pre).__init__()
         yield pre
@@ -73,8 +73,8 @@ class TestPreProcessing:
     def test_create_set_split_all_stations(self, caplog, obj_with_exp_setup):
         caplog.set_level(logging.DEBUG)
         obj_with_exp_setup.create_set_split(slice(0, 2), "awesome")
-        assert caplog.record_tuples[0] == ('root', 10, "Awesome stations (len=5): ['DEBW107', 'DEBY081', 'DEBW013', "
-                                                       "'DEBW076', 'DEBW087']")
+        assert caplog.record_tuples[0] == ('root', 10, "Awesome stations (len=6): ['DEBW107', 'DEBY081', 'DEBW013', "
+                                                       "'DEBW076', 'DEBW087', 'DEBW001']")
         data_store = obj_with_exp_setup.data_store
         assert isinstance(data_store.get("generator", "general.awesome"), DataGenerator)
         with pytest.raises(NameNotFoundInScope):
@@ -88,9 +88,11 @@ class TestPreProcessing:
         kwargs = pre._create_args_dict(DEFAULT_KWARGS_LIST)
         stations = pre.data_store.get("stations", "general")
         valid_stations = pre.check_valid_stations(args, kwargs, stations)
-        assert valid_stations == stations
+        assert len(valid_stations) < len(stations)
+        assert valid_stations == stations[:-1]
         assert caplog.record_tuples[0] == ('root', 20, 'check valid stations started')
-        assert caplog.record_tuples[-1] == ('root', 20, PyTestRegex(r'run for \d+\.\d+s to check 5 station\(s\)'))
+        assert caplog.record_tuples[-1] == ('root', 20, PyTestRegex(r'run for \d+\.\d+s to check 6 station\(s\). Found '
+                                                                    r'5/6 valid stations.'))
 
     def test_split_set_indices(self, obj_no_init):
         dummy_list = list(range(0, 15))