diff --git a/notebooks/amenities/amenity_index_choropleth.ipynb b/notebooks/amenities/amenity_index_choropleth.ipynb
index 11ffbbe..fa157d3 100644
--- a/notebooks/amenities/amenity_index_choropleth.ipynb
+++ b/notebooks/amenities/amenity_index_choropleth.ipynb
@@ -38,7 +38,7 @@
     "# Load .env from project root\n",
     "load_dotenv('../../.env')\n",
     "\n",
-    "engine = create_engine(os.environ.get('DATABASE_URL'))\n",
+    "engine = create_engine(os.environ['DATABASE_URL'])\n",
     "\n",
     "query = \"\"\"\n",
     "SELECT\n",
diff --git a/notebooks/amenities/amenity_radar.ipynb b/notebooks/amenities/amenity_radar.ipynb
index 551025f..99327d5 100644
--- a/notebooks/amenities/amenity_radar.ipynb
+++ b/notebooks/amenities/amenity_radar.ipynb
@@ -29,7 +29,7 @@
    "execution_count": null,
    "metadata": {},
    "outputs": [],
-   "source": "import pandas as pd\nfrom sqlalchemy import create_engine\nfrom dotenv import load_dotenv\nimport os\n\n# Load .env from project root\nload_dotenv('../../.env')\n\nengine = create_engine(os.environ.get('DATABASE_URL'))\n\nquery = \"\"\"\nSELECT\n    neighbourhood_name,\n    parks_index,\n    schools_index,\n    transit_index,\n    amenity_index,\n    amenity_tier\nFROM public_marts.mart_neighbourhood_amenities\nWHERE year = (SELECT MAX(year) FROM public_marts.mart_neighbourhood_amenities)\nORDER BY amenity_index DESC\n\"\"\"\n\ndf = pd.read_sql(query, engine)\nprint(f\"Loaded {len(df)} neighbourhoods\")"
+   "source": "import pandas as pd\nfrom sqlalchemy import create_engine\nfrom dotenv import load_dotenv\nimport os\n\n# Load .env from project root\nload_dotenv('../../.env')\n\nengine = create_engine(os.environ['DATABASE_URL'])\n\nquery = \"\"\"\nSELECT\n    neighbourhood_name,\n    parks_index,\n    schools_index,\n    transit_index,\n    amenity_index,\n    amenity_tier\nFROM public_marts.mart_neighbourhood_amenities\nWHERE year = (SELECT MAX(year) FROM public_marts.mart_neighbourhood_amenities)\nORDER BY amenity_index DESC\n\"\"\"\n\ndf = pd.read_sql(query, engine)\nprint(f\"Loaded {len(df)} neighbourhoods\")"
   },
   {
    "cell_type": "markdown",
diff --git a/notebooks/amenities/transit_accessibility_bar.ipynb b/notebooks/amenities/transit_accessibility_bar.ipynb
index 0635a15..126843b 100644
--- a/notebooks/amenities/transit_accessibility_bar.ipynb
+++ b/notebooks/amenities/transit_accessibility_bar.ipynb
@@ -38,7 +38,7 @@
     "# Load .env from project root\n",
     "load_dotenv('../../.env')\n",
     "\n",
-    "engine = create_engine(os.environ.get('DATABASE_URL'))\n",
+    "engine = create_engine(os.environ['DATABASE_URL'])\n",
     "\n",
     "query = \"\"\"\n",
     "SELECT\n",
diff --git a/notebooks/demographics/age_distribution.ipynb b/notebooks/demographics/age_distribution.ipynb
index 64ec4b2..208bb6d 100644
--- a/notebooks/demographics/age_distribution.ipynb
+++ b/notebooks/demographics/age_distribution.ipynb
@@ -38,7 +38,7 @@
     "# Load .env from project root\n",
     "load_dotenv('../../.env')\n",
     "\n",
-    "engine = create_engine(os.environ.get('DATABASE_URL'))\n",
+    "engine = create_engine(os.environ['DATABASE_URL'])\n",
     "\n",
     "query = \"\"\"\n",
     "SELECT\n",
diff --git a/notebooks/demographics/income_choropleth.ipynb b/notebooks/demographics/income_choropleth.ipynb
index 73115a5..8eaef95 100644
--- a/notebooks/demographics/income_choropleth.ipynb
+++ b/notebooks/demographics/income_choropleth.ipynb
@@ -38,7 +38,7 @@
     "# Load .env from project root\n",
     "load_dotenv('../../.env')\n",
     "\n",
-    "engine = create_engine(os.environ.get('DATABASE_URL'))\n",
+    "engine = create_engine(os.environ['DATABASE_URL'])\n",
     "\n",
     "query = \"\"\"\n",
     "SELECT\n",
diff --git a/notebooks/demographics/population_density_bar.ipynb b/notebooks/demographics/population_density_bar.ipynb
index 27b073a..8c7cd23 100644
--- a/notebooks/demographics/population_density_bar.ipynb
+++ b/notebooks/demographics/population_density_bar.ipynb
@@ -38,7 +38,7 @@
     "# Load .env from project root\n",
     "load_dotenv('../../.env')\n",
     "\n",
-    "engine = create_engine(os.environ.get('DATABASE_URL'))\n",
+    "engine = create_engine(os.environ['DATABASE_URL'])\n",
     "\n",
     "query = \"\"\"\n",
     "SELECT\n",
diff --git a/notebooks/housing/affordability_choropleth.ipynb b/notebooks/housing/affordability_choropleth.ipynb
index 63534b2..ca2f054 100644
--- a/notebooks/housing/affordability_choropleth.ipynb
+++ b/notebooks/housing/affordability_choropleth.ipynb
@@ -38,7 +38,7 @@
     "# Load .env from project root\n",
     "load_dotenv('../../.env')\n",
     "\n",
-    "engine = create_engine(os.environ.get('DATABASE_URL'))\n",
+    "engine = create_engine(os.environ['DATABASE_URL'])\n",
     "\n",
     "query = \"\"\"\n",
     "SELECT\n",
diff --git a/notebooks/housing/rent_trend_line.ipynb b/notebooks/housing/rent_trend_line.ipynb
index 8299cf3..a658ab1 100644
--- a/notebooks/housing/rent_trend_line.ipynb
+++ b/notebooks/housing/rent_trend_line.ipynb
@@ -38,7 +38,7 @@
     "# Load .env from project root\n",
     "load_dotenv('../../.env')\n",
     "\n",
-    "engine = create_engine(os.environ.get('DATABASE_URL'))\n",
+    "engine = create_engine(os.environ['DATABASE_URL'])\n",
     "\n",
     "# City-wide average rent by year\n",
     "query = \"\"\"\n",
diff --git a/notebooks/housing/tenure_breakdown_bar.ipynb b/notebooks/housing/tenure_breakdown_bar.ipynb
index 084a27f..413f6b8 100644
--- a/notebooks/housing/tenure_breakdown_bar.ipynb
+++ b/notebooks/housing/tenure_breakdown_bar.ipynb
@@ -38,7 +38,7 @@
     "# Load .env from project root\n",
     "load_dotenv('../../.env')\n",
     "\n",
-    "engine = create_engine(os.environ.get('DATABASE_URL'))\n",
+    "engine = create_engine(os.environ['DATABASE_URL'])\n",
     "\n",
     "query = \"\"\"\n",
     "SELECT\n",
diff --git a/notebooks/overview/income_safety_scatter.ipynb b/notebooks/overview/income_safety_scatter.ipynb
index 86fb16c..da41fb2 100644
--- a/notebooks/overview/income_safety_scatter.ipynb
+++ b/notebooks/overview/income_safety_scatter.ipynb
@@ -38,7 +38,7 @@
     "# Load .env from project root\n",
     "load_dotenv('../../.env')\n",
     "\n",
-    "engine = create_engine(os.environ.get('DATABASE_URL'))\n",
+    "engine = create_engine(os.environ['DATABASE_URL'])\n",
     "\n",
     "query = \"\"\"\n",
     "SELECT\n",
diff --git a/notebooks/overview/livability_choropleth.ipynb b/notebooks/overview/livability_choropleth.ipynb
index 1b110a6..580bc59 100644
--- a/notebooks/overview/livability_choropleth.ipynb
+++ b/notebooks/overview/livability_choropleth.ipynb
@@ -29,7 +29,7 @@
    "execution_count": null,
    "metadata": {},
    "outputs": [],
-   "source": "import pandas as pd\nfrom sqlalchemy import create_engine\nfrom dotenv import load_dotenv\nimport os\n\n# Load .env from project root\nload_dotenv('../../.env')\n\nengine = create_engine(os.environ.get('DATABASE_URL'))\n\nquery = \"\"\"\nSELECT\n    neighbourhood_id,\n    neighbourhood_name,\n    geometry,\n    year,\n    livability_score,\n    safety_score,\n    affordability_score,\n    amenity_score,\n    population,\n    median_household_income\nFROM public_marts.mart_neighbourhood_overview\nWHERE year = (SELECT MAX(year) FROM public_marts.mart_neighbourhood_overview)\nORDER BY livability_score DESC\n\"\"\"\n\ndf = pd.read_sql(query, engine)\nprint(f\"Loaded {len(df)} neighbourhoods\")"
+   "source": "import pandas as pd\nfrom sqlalchemy import create_engine\nfrom dotenv import load_dotenv\nimport os\n\n# Load .env from project root\nload_dotenv('../../.env')\n\nengine = create_engine(os.environ['DATABASE_URL'])\n\nquery = \"\"\"\nSELECT\n    neighbourhood_id,\n    neighbourhood_name,\n    geometry,\n    year,\n    livability_score,\n    safety_score,\n    affordability_score,\n    amenity_score,\n    population,\n    median_household_income\nFROM public_marts.mart_neighbourhood_overview\nWHERE year = (SELECT MAX(year) FROM public_marts.mart_neighbourhood_overview)\nORDER BY livability_score DESC\n\"\"\"\n\ndf = pd.read_sql(query, engine)\nprint(f\"Loaded {len(df)} neighbourhoods\")"
   },
   {
    "cell_type": "markdown",
diff --git a/notebooks/overview/top_bottom_10_bar.ipynb b/notebooks/overview/top_bottom_10_bar.ipynb
index 2b204d9..6468ea3 100644
--- a/notebooks/overview/top_bottom_10_bar.ipynb
+++ b/notebooks/overview/top_bottom_10_bar.ipynb
@@ -38,7 +38,7 @@
     "# Load .env from project root\n",
     "load_dotenv('../../.env')\n",
     "\n",
-    "engine = create_engine(os.environ.get('DATABASE_URL'))\n",
+    "engine = create_engine(os.environ['DATABASE_URL'])\n",
     "\n",
     "query = \"\"\"\n",
     "SELECT\n",
diff --git a/notebooks/safety/crime_breakdown_bar.ipynb b/notebooks/safety/crime_breakdown_bar.ipynb
index 5e5fb46..2ff6d43 100644
--- a/notebooks/safety/crime_breakdown_bar.ipynb
+++ b/notebooks/safety/crime_breakdown_bar.ipynb
@@ -38,7 +38,7 @@
     "# Load .env from project root\n",
     "load_dotenv('../../.env')\n",
     "\n",
-    "engine = create_engine(os.environ.get('DATABASE_URL'))\n",
+    "engine = create_engine(os.environ['DATABASE_URL'])\n",
     "\n",
     "query = \"\"\"\n",
     "SELECT\n",
diff --git a/notebooks/safety/crime_rate_choropleth.ipynb b/notebooks/safety/crime_rate_choropleth.ipynb
index 1d72390..05c3225 100644
--- a/notebooks/safety/crime_rate_choropleth.ipynb
+++ b/notebooks/safety/crime_rate_choropleth.ipynb
@@ -38,7 +38,7 @@
     "# Load .env from project root\n",
     "load_dotenv('../../.env')\n",
     "\n",
-    "engine = create_engine(os.environ.get('DATABASE_URL'))\n",
+    "engine = create_engine(os.environ['DATABASE_URL'])\n",
     "\n",
     "query = \"\"\"\n",
     "SELECT\n",
diff --git a/notebooks/safety/crime_trend_line.ipynb b/notebooks/safety/crime_trend_line.ipynb
index bd062b0..3e3a3a5 100644
--- a/notebooks/safety/crime_trend_line.ipynb
+++ b/notebooks/safety/crime_trend_line.ipynb
@@ -38,7 +38,7 @@
     "# Load .env from project root\n",
     "load_dotenv('../../.env')\n",
     "\n",
-    "engine = create_engine(os.environ.get('DATABASE_URL'))\n",
+    "engine = create_engine(os.environ['DATABASE_URL'])\n",
     "\n",
     "query = \"\"\"\n",
     "SELECT\n",