diff --git a/inc/TRestGeant4PrimaryGeneratorInfo.h b/inc/TRestGeant4PrimaryGeneratorInfo.h
index 75eab77..927e66f 100644
--- a/inc/TRestGeant4PrimaryGeneratorInfo.h
+++ b/inc/TRestGeant4PrimaryGeneratorInfo.h
@@ -52,7 +52,8 @@ enum class EnergyDistributionFormulas {
     COSMIC_NEUTRONS,
     COSMIC_GAMMAS,
     FISSION_NEUTRONS_U238,
-    ENVIRONMENTAL_GAMMAS
+    ENVIRONMENTAL_GAMMAS,
+    ENVIRONMENTAL_NEUTRONS,
 };
 
 std::string EnergyDistributionFormulasToString(const EnergyDistributionFormulas&);
diff --git a/src/TRestGeant4PrimaryGeneratorInfo.cxx b/src/TRestGeant4PrimaryGeneratorInfo.cxx
index 512393c..34812c1 100644
--- a/src/TRestGeant4PrimaryGeneratorInfo.cxx
+++ b/src/TRestGeant4PrimaryGeneratorInfo.cxx
@@ -178,6 +178,8 @@ string TRestGeant4PrimaryGeneratorTypes::EnergyDistributionFormulasToString(
             return "FissionNeutronsU238";
         case EnergyDistributionFormulas::ENVIRONMENTAL_GAMMAS:
             return "EnvironmentalGammas";
+        case EnergyDistributionFormulas::ENVIRONMENTAL_NEUTRONS:
+            return "EnvironmentalNeutrons";
     }
     cout << "TRestGeant4PrimaryGeneratorTypes::EnergyDistributionFormulasToString - Error - Unknown energy "
             "distribution formula"
@@ -202,6 +204,10 @@ EnergyDistributionFormulas TRestGeant4PrimaryGeneratorTypes::StringToEnergyDistr
                    EnergyDistributionFormulasToString(EnergyDistributionFormulas::ENVIRONMENTAL_GAMMAS),
                    TString::ECaseCompare::kIgnoreCase)) {
         return EnergyDistributionFormulas::ENVIRONMENTAL_GAMMAS;
+    } else if (TString(type).EqualTo(
+                   EnergyDistributionFormulasToString(EnergyDistributionFormulas::ENVIRONMENTAL_NEUTRONS),
+                   TString::ECaseCompare::kIgnoreCase)) {
+        return EnergyDistributionFormulas::ENVIRONMENTAL_NEUTRONS;
     } else {
         cout << "TRestGeant4PrimaryGeneratorTypes::StringToEnergyDistributionFormulas - Error - Unknown "
                 "energyDistributionFormulas: "
@@ -250,6 +256,15 @@ TF1 TRestGeant4PrimaryGeneratorTypes::EnergyDistributionFormulasToRootFormula(
             distribution.GetXaxis()->SetTitle("Energy (keV)");
             return distribution;
         }
+        case EnergyDistributionFormulas::ENVIRONMENTAL_NEUTRONS: {
+            // Environmental neutron radiation approximation
+            const char* title = "Environmental Neutrons";
+            auto distribution = TF1(title, "TMath::Exp(-x * 0.0005)", 0, 10000);  // keV
+            distribution.SetNormalized(true);
+            distribution.SetTitle(title);
+            distribution.GetXaxis()->SetTitle("Energy (keV)");
+            return distribution;
+        }
     }
     cout << "TRestGeant4PrimaryGeneratorTypes::EnergyDistributionFormulasToRootFormula - Error - Unknown "
             "energy distribution formula"