diff --git a/city_metrix/layers/cams.py b/city_metrix/layers/cams.py
index f3e3a4c..b1fbf08 100644
--- a/city_metrix/layers/cams.py
+++ b/city_metrix/layers/cams.py
@@ -7,30 +7,36 @@
 
 
 class Cams(Layer):
-    def __init__(self, start_date="2023-01-01", end_date="2023-12-01", **kwargs):
+    def __init__(self, start_date="2023-01-01", end_date="2023-12-01", species, **kwargs):
         super().__init__(**kwargs)
         self.start_date = start_date
         self.end_date = end_date
+		if species in ("particulate_matter_2.5um", "particulate_matter_10um", "carbon_monoxide", "nitrogen_dioxide", "ozone", "sulphur_dioxide"):
+		    self.species = species
+		else:
+		    raise Exception("Selected species not supported")
 
     def get_data(self, bbox):
         min_lon, min_lat, max_lon, max_lat = bbox
 
         c = cdsapi.Client()
-        c.retrieve(
-            'cams-global-reanalysis-eac4',
-            {
-                'variable': [
-                    "2m_temperature", "mean_sea_level_pressure",
-                    "particulate_matter_2.5um", "particulate_matter_10um",
-                    "carbon_monoxide", "nitrogen_dioxide", "ozone", "sulphur_dioxide"
-
-                ],
+		query_dict = {
                 "model_level": ["60"],
                 "date": [f"{self.start_date}/{self.end_date}"],
                 'time': ['00:00', '03:00', '06:00', '09:00', '12:00', '15:00', '18:00', '21:00'],
                 'area': [max_lat, min_lon, min_lat, max_lon],
                 'data_format': 'netcdf_zip',
-            },
+            }
+		if self.species in ("particulate_matter_2.5um", "particulate_matter_10um"):
+		    query_dict['variable'] = [self.species]
+		else:
+		    query_dict['variable'] = [
+			        "2m_temperature", "mean_sea_level_pressure", self.species
+			    ]
+
+        c.retrieve(
+            'cams-global-reanalysis-eac4',
+            query_dict,
             'cams_download.zip')
 
         # extract the ZIP file
@@ -52,6 +58,7 @@ def get_data(self, bbox):
             else dataarray
             for dataarray in dataarray_list
         ]
+
         # drop coordinate ['latitude','longitude'] if uses 360 degree system
         dataarray_list = [
             dataarray.drop_vars(['latitude', 'longitude'])