diff --git a/CHANGELOG b/CHANGELOG
index a7b6e9c3f1ac43bfc3ce0888d390d9606066a3bc..de2b6711c84967ea337ceb423cdd27121c4437df 100755
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -1,3 +1,8 @@
+1.0.4
+    2020/07/17
+
+    - Fixed bug on WRF-Chem writer
+
 1.0.3
     2020/07/06
 
diff --git a/hermesv3_bu/__init__.py b/hermesv3_bu/__init__.py
index 976498ab9cacbd0ed9a538cebd482e5df53f8efb..92192eed4fc88eaee9fdbafbc8e2139c43ba00e2 100755
--- a/hermesv3_bu/__init__.py
+++ b/hermesv3_bu/__init__.py
@@ -1 +1 @@
-__version__ = "1.0.3"
+__version__ = "1.0.4"
diff --git a/hermesv3_bu/writer/monarch_writer.py b/hermesv3_bu/writer/monarch_writer.py
index 0ac0ed0dd49003c24b6670eee47541f2667e4787..caa03087a4c7cbfe3df95c2b4c251ccd662b350e 100755
--- a/hermesv3_bu/writer/monarch_writer.py
+++ b/hermesv3_bu/writer/monarch_writer.py
@@ -89,7 +89,6 @@ class MonarchWriter(Writer):
         if self.comm_write.Get_rank() == 0:
             self.grid.add_cell_area()
             cell_area = self.grid.shapefile[['cell_area']]
-            # cell_area.set_index('FID', inplace=True)
         else:
             cell_area = None
         cell_area = self.comm_write.bcast(cell_area, root=0)
diff --git a/hermesv3_bu/writer/wrfchem_writer.py b/hermesv3_bu/writer/wrfchem_writer.py
index 1f14ddead70c38345819c100f6bb8bd59664bebc..0614921237ab0154603e16db1634d969c34215f9 100755
--- a/hermesv3_bu/writer/wrfchem_writer.py
+++ b/hermesv3_bu/writer/wrfchem_writer.py
@@ -106,23 +106,23 @@ class WrfChemWriter(Writer):
 
         if self.comm_write.Get_rank() == 0:
             self.grid.add_cell_area()
-
-            cell_area = self.grid.shapefile[['FID', 'cell_area']]
-            cell_area.set_index('FID', inplace=True)
+            cell_area = self.grid.shapefile[['cell_area']]
         else:
             cell_area = None
         cell_area = self.comm_write.bcast(cell_area, root=0)
 
+        emissions = emissions.reset_index().groupby(['FID', 'layer', 'tstep']).sum()
         # From mol/h or g/h to mol/m2.h or g/m2.h
         emissions = emissions.divide(cell_area['cell_area'], axis=0, level='FID')
-
+        print(emissions.columns)
         for pollutant, info in self.pollutant_info.iterrows():
-            if info.get('units') == "ug/m3 m/s":
-                # From g/m2.h to ug/m2.s
-                emissions[[pollutant]] = emissions[[pollutant]].mul(10**6 / 3600)
-            elif info.get('units') == "mol km^-2 hr^-1":
-                # From mol/m2.h to mol/km2.h
-                emissions[[pollutant]] = emissions[[pollutant]].mul(10**6)
+            if pollutant in emissions.columns:
+                if info.get('units') == "ug/m3 m/s":
+                    # From g/m2.h to ug/m2.s
+                    emissions[pollutant] = emissions[pollutant].mul(10**6 / 3600)
+                elif info.get('units') == "mol km^-2 hr^-1":
+                    # From mol/m2.h to mol/km2.h
+                    emissions[pollutant] = emissions[pollutant].mul(10**6)
 
         self.logger.write_time_log('WrfChemWriter', 'unit_change', timeit.default_timer() - spent_time)
         return emissions