diff --git a/src/accessor/grib_accessor_class_g2_aerosol.cc b/src/accessor/grib_accessor_class_g2_aerosol.cc
index f32d51e7c..641e4e125 100644
--- a/src/accessor/grib_accessor_class_g2_aerosol.cc
+++ b/src/accessor/grib_accessor_class_g2_aerosol.cc
@@ -79,7 +79,7 @@ int grib_accessor_g2_aerosol_t::pack_long(const long* val, size_t* len)
     }
     else {
         if (isInstant) {
-            productDefinitionTemplateNumberNew = 48;  // 44 is deprecated
+            productDefinitionTemplateNumberNew = 50;  // ECC-1963: 44 is deprecated
         }
         else {
             productDefinitionTemplateNumberNew = 46;
diff --git a/src/accessor/grib_accessor_class_select_step_template.cc b/src/accessor/grib_accessor_class_select_step_template.cc
index e37f62fa3..00cb2ca7b 100644
--- a/src/accessor/grib_accessor_class_select_step_template.cc
+++ b/src/accessor/grib_accessor_class_select_step_template.cc
@@ -70,7 +70,7 @@ int grib_accessor_select_step_template_t::pack_long(const long* val, size_t* len
                 productDefinitionTemplateNumberNew = 41;
                 break;
             case 46:                                      // DET aerosol
-                productDefinitionTemplateNumberNew = 48;  // 44 is deprecated
+                productDefinitionTemplateNumberNew = 50;  // ECC-1963: 44 is deprecated
                 break;
             case 47:  // ENS aerosol
                 productDefinitionTemplateNumberNew = 45;
diff --git a/src/grib_util.cc b/src/grib_util.cc
index a3998926b..abc72d830 100644
--- a/src/grib_util.cc
+++ b/src/grib_util.cc
@@ -1950,12 +1950,13 @@ int grib2_is_PDTN_ChemicalDistFunc(long pdtn)
 // Return 1 if the productDefinitionTemplateNumber (GRIB2) is for aerosols
 int grib2_is_PDTN_Aerosol(long pdtn)
 {
-    // Notes: PDT 44 is deprecated and replaced by 48
+    // Notes: PDT 44 is deprecated and replaced by 50
     //        PDT 47 is deprecated and replaced by 85
     return (
         pdtn == 44 ||
         pdtn == 48 ||
         pdtn == 49 ||
+        pdtn == 50 ||
         pdtn == 45 ||
         pdtn == 46 ||
         pdtn == 47 ||
@@ -2014,6 +2015,9 @@ int grib2_choose_PDTN(int current_PDTN, bool is_det, bool is_instant)
         if (is_interval && is_ens) return 85;
         if (is_interval && is_det) return 46;
     }
+    if (current_PDTN == 50) {
+        if (is_instant && is_ens) return 45;
+    }
 
     return current_PDTN;  // no change
 }
@@ -2102,7 +2106,7 @@ int grib2_select_PDTN(int is_eps, int is_instant,
         }
         else {
             if (is_instant)
-                return 48; // 44 is deprecated
+                return 50; // ECC-1963: 44 is deprecated
             else
                 return 46;
         }
diff --git a/tests/grib2_chemicals_aerosols.sh b/tests/grib2_chemicals_aerosols.sh
index 645dbc8e1..6ab0649a2 100755
--- a/tests/grib2_chemicals_aerosols.sh
+++ b/tests/grib2_chemicals_aerosols.sh
@@ -55,8 +55,8 @@ grib_check_key_equals $temp constituentType,numberOfModeOfDistribution,modeNumbe
 
 # Plain aerosols
 ${tools_dir}/grib_set -s tablesVersion=$latest,is_aerosol=1 $sample2 $temp
-grib_check_key_equals $temp productDefinitionTemplateNumber '48'
-grib_check_key_equals $temp aerosolType,typeOfSizeInterval,typeOfWavelengthInterval '0 0 0'
+grib_check_key_equals $temp productDefinitionTemplateNumber '50'
+grib_check_key_equals $temp aerosolType,typeOfSizeInterval '0 0'
 
 # Aerosol optical
 ${tools_dir}/grib_set -s tablesVersion=$latest,is_aerosol_optical=1 $sample2 $temp
diff --git a/tests/grib2_templates.sh b/tests/grib2_templates.sh
index 800a5aca9..47cdc3bce 100755
--- a/tests/grib2_templates.sh
+++ b/tests/grib2_templates.sh
@@ -242,7 +242,7 @@ grib_check_key_equals $temp productDefinitionTemplateNumber '43'
 
 # Aerosol 210072
 $tools_dir/grib_set -s paramId=210072,stepType=instant,eps=0 $input $temp
-grib_check_key_equals $temp productDefinitionTemplateNumber '48'
+grib_check_key_equals $temp productDefinitionTemplateNumber '50'
 
 $tools_dir/grib_set -s paramId=210072,stepType=instant,eps=1 $input $temp
 grib_check_key_equals $temp productDefinitionTemplateNumber '45'
diff --git a/tests/grib_local_ECMWF.sh b/tests/grib_local_ECMWF.sh
index 830dd124d..a081322cc 100755
--- a/tests/grib_local_ECMWF.sh
+++ b/tests/grib_local_ECMWF.sh
@@ -222,7 +222,7 @@ ${tools_dir}/grib_set -s productDefinitionTemplateNumber=76,paramId=456000,setLo
 grib_check_key_equals $temp shortName drydep_vel_vol
 
 ${tools_dir}/grib_set -s paramId=215225,setLocalDefinition=1,localDefinitionNumber=36 $sample_g2 $temp
-grib_check_key_equals $temp productDefinitionTemplateNumber 48
+grib_check_key_equals $temp productDefinitionTemplateNumber 50
 
 ${tools_dir}/grib_set -s paramId=210251,setLocalDefinition=1,localDefinitionNumber=36 $sample_g2 $temp
 
diff --git a/tests/grib_sub_hourly.sh b/tests/grib_sub_hourly.sh
index a7a47f69f..4c4cd0e50 100755
--- a/tests/grib_sub_hourly.sh
+++ b/tests/grib_sub_hourly.sh
@@ -621,7 +621,7 @@ ${tools_dir}/grib_set -s stepUnits=s,paramId=131060 $sample_g2 $temp # probabili
 grib_check_key_equals $temp '-p indicatorOfUnitOfTimeRange,stepUnits:s,productDefinitionTemplateNumber' '13 s 9'
 
 ${tools_dir}/grib_set -s stepUnits=s,paramId=210073 $sample_g2 $temp # is_aerosol
-grib_check_key_equals $temp '-p indicatorOfUnitOfTimeRange,stepUnits:s,productDefinitionTemplateNumber' '13 s 48'
+grib_check_key_equals $temp '-p indicatorOfUnitOfTimeRange,stepUnits:s,productDefinitionTemplateNumber' '13 s 50'
 
 ${tools_dir}/grib_set -s stepUnits=s,paramId=210170 $sample_g2 $temp # is_chemical_srcsink
 grib_check_key_equals $temp '-p indicatorOfUnitOfTimeRange,stepUnits:s,productDefinitionTemplateNumber' '13 s 76'
diff --git a/tests/unit_tests.cc b/tests/unit_tests.cc
index c401b94aa..f0f1e8ffa 100644
--- a/tests/unit_tests.cc
+++ b/tests/unit_tests.cc
@@ -742,7 +742,7 @@ void test_grib2_select_PDTN()
     Assert( 67 == grib2_select_PDTN(!eps, !instant,  0, 0, chemical_distfn, 0, 0) );
 
     // Aerosols
-    Assert( 48 == grib2_select_PDTN(!eps, instant,  0, 0, 0, aerosol, 0) );
+    Assert( 50 == grib2_select_PDTN(!eps, instant,  0, 0, 0, aerosol, 0) );
     Assert( 46 == grib2_select_PDTN(!eps, !instant, 0, 0, 0, aerosol, 0) );
     Assert( 45 == grib2_select_PDTN(eps, instant,   0, 0, 0, aerosol, 0) );
     Assert( 85 == grib2_select_PDTN(eps, !instant,  0, 0, 0, aerosol, 0) );