diff --git a/datahub/main.py b/datahub/main.py
index 2364fa6..c6f263c 100644
--- a/datahub/main.py
+++ b/datahub/main.py
@@ -1,4 +1,5 @@
 """Script for running Datahub API."""
+import numpy as np
 from fastapi import FastAPI, HTTPException, UploadFile
 from fastapi.responses import ORJSONResponse
 
@@ -208,19 +209,25 @@ def get_dsr_data(
                 message = "One or more of the specified columns are invalid."
                 log.error(message)
                 raise HTTPException(status_code=400, detail=message)
-
-        log.info("Filtering data by column...")
-        filtered_data = []
-        for frame in filtered_index_data:
-            filtered_keys = {}
-            for key in frame.keys():
-                if dsr_headers[key.title()] in columns:
-                    filtered_keys[key] = frame[key]
-            filtered_data.append(filtered_keys)
-
-        return ORJSONResponse({"data": filtered_data})
-
-    return ORJSONResponse({"data": filtered_index_data})
+    else:
+        columns = list(dsr_headers.values())
+
+    log.info("Filtering data by column...")
+    filtered_data = []
+    for frame in filtered_index_data:
+        filtered_keys = {}
+        for key, value in frame.items():
+            if dsr_headers[key.title()] not in columns:
+                continue
+            elif not isinstance(value, str) and np.issubdtype(
+                value.dtype, np.character
+            ):
+                filtered_keys[key] = value.astype(str).tolist()
+            else:
+                filtered_keys[key] = value
+        filtered_data.append(filtered_keys)
+
+    return ORJSONResponse({"data": filtered_data})
 
 
 @app.get("/wesim")
diff --git a/tests/conftest.py b/tests/conftest.py
index 00f2075..daba1c1 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -61,7 +61,8 @@ def dsr_data_path(tmp_path):
                 shape = field.field_info.extra["shape"]
                 if shape[0] is None:
                     shape = (10, shape[1])
-                h5file[field.alias] = np.random.rand(*shape).astype("float32")
+                dtype = "|S13" if field.alias == "Activity Types" else "float32"
+                h5file[field.alias] = np.random.rand(*shape).astype(dtype)
 
     # Return the path to the file
     return file_path
diff --git a/tests/test_dsr_api.py b/tests/test_dsr_api.py
index 768f1d4..71a71d1 100644
--- a/tests/test_dsr_api.py
+++ b/tests/test_dsr_api.py
@@ -69,6 +69,9 @@ def test_get_dsr_api(dsr_data):
         if key in ["Name", "Warn"]:
             assert received == expected
             continue
+        if key in ["Activity Types"]:
+            assert received == expected.astype(str).tolist()
+            continue
         assert np.allclose(received, expected)
 
     # Add another entry with changed data