diff --git a/Environment/HydrogenSphere/HydrogenSphere.h b/Environment/HydrogenSphere/HydrogenSphere.h
index aaf15e89f714afdb7750f2c96b303e0b384d8785..ca5b0f31439f0d35c82bc21e64b283f866df3758 100644
--- a/Environment/HydrogenSphere/HydrogenSphere.h
+++ b/Environment/HydrogenSphere/HydrogenSphere.h
@@ -9,6 +9,8 @@
  * a fSphere homogeneously filled with hydrogen
  */
 
+namespace corsika::environment {
+
 class HydrogenSphere {
   CoordinateSystem const& fCS;
   corsika::geometry::Sphere const fSphere;
@@ -25,7 +27,7 @@ public:
                                : corsika::particles::Code::Unknown;
   }
 
-  MassDensityType GetDensity(Point const& p) const { return density; };
+  MassDensityType GetDensity(Point const& p) const { return fSphere.isInside(p) ? density : 0_kg / (meter*meter*meter); };
 
   GetMagneticField(Point const& p) {
     QuantityVector<magnetic_flux_density_d> components{0 * corsika::units::tesla,
@@ -35,4 +37,5 @@ public:
   }
 };
 
+}
 #endif