diff --git a/backend/src/Command/GenerateTilesCommand.php b/backend/src/Command/GenerateTilesCommand.php
index d9063eb..710b8e9 100644
--- a/backend/src/Command/GenerateTilesCommand.php
+++ b/backend/src/Command/GenerateTilesCommand.php
@@ -63,10 +63,10 @@ class GenerateTilesCommand extends Command
     private function queryObservationsGeoJSON(): ?string
     {
         $rows = $this->connection->fetchAllAssociative(
-            "SELECT ST_AsGeoJSON(geometry) AS geometry, afai_mean AS afai
+            "SELECT ST_AsGeoJSON(geometry) AS geometry, COALESCE(afai_mean, 0) AS afai
              FROM sargassum_observation
              WHERE detected_at >= NOW() - INTERVAL '30 days'
-               AND afai_mean > 0
+               AND coverage_area > 0
              ORDER BY detected_at DESC"
         );