diff --git a/module3/exo1/analyse-syndrome-grippal.ipynb b/module3/exo1/analyse-syndrome-grippal.ipynb
index 7bc1d5e28704e58b6023787fdc9bc49703377751..a30c6fbd565142278b5984ee9cb4acfd50cebf75 100644
--- a/module3/exo1/analyse-syndrome-grippal.ipynb
+++ b/module3/exo1/analyse-syndrome-grippal.ipynb
@@ -1039,11 +1039,11 @@
    ],
    "source": [
     "if \"incidence-PAY-3.csv\" not in os.listdir():    \n",
-    "    raw_data = pd.read_csv(data_url, skiprows=1)\n",
+    "    raw_data = pd.read_csv(data_url, skiprows=1) # if csv file is not present in local download from sentinel\n",
     "    raw_data.to_csv(\"incidence-PAY-3.csv\", index=False)\n",
     "    print(\"downloaded from source URL\")\n",
     "else:\n",
-    "    raw_data = pd.read_csv(\"incidence-PAY-3.csv\")\n",
+    "    raw_data = pd.read_csv(\"incidence-PAY-3.csv\") # future proofed local version, in case sentinel changes url\n",
     "    print(\"csv loaded from local\")\n",
     "raw_data"
    ]