diff --git a/data/json/monsters/fungus.json b/data/json/monsters/fungus.json
index d398ac550bc0b..7159a2eb35361 100644
--- a/data/json/monsters/fungus.json
+++ b/data/json/monsters/fungus.json
@@ -363,7 +363,7 @@
     "vision_day": 5,
     "vision_night": 5,
     "harvest": "exempt",
-    "emit_fields": [ "emit_fungal_leak" ],
+    "emit_fields": [ { "emit_id": "emit_fungal_leak", "delay": "1 s" } ],
     "special_attacks": [ [ "SUICIDE", 20 ], [ "scratch", 15 ] ],
     "death_drops": "default_zombie_items",
     "death_function": [ "FUNGALBURST" ],
@@ -397,7 +397,7 @@
     "vision_day": 5,
     "vision_night": 3,
     "harvest": "zombie",
-    "emit_fields": [ "emit_fungal_haze_plume" ],
+    "emit_fields": [ { "emit_id": "emit_fungal_haze_plume", "delay": "1 s" } ],
     "special_attacks": [ { "type": "bite", "cooldown": 5 }, [ "scratch", 15 ] ],
     "death_function": [ "FUNGUS" ],
     "flags": [ "SEES", "STUMBLES", "WARM", "BASHES", "GROUP_BASH", "POISON", "HARDTOSHOOT", "NO_BREATHE", "PUSH_MON", "FILTHY" ]
diff --git a/data/json/monsters/nether.json b/data/json/monsters/nether.json
index 0cfb6a8c256e2..66e84b39199c6 100644
--- a/data/json/monsters/nether.json
+++ b/data/json/monsters/nether.json
@@ -483,7 +483,7 @@
     "vision_night": 50,
     "harvest": "exempt",
     "special_attacks": [ [ "TINDALOS_TELEPORT", 5 ] ],
-    "emit_fields": [ "emit_tindalos_gas_leak" ],
+    "emit_fields": [ { "emit_id": "emit_tindalos_gas_leak", "delay": "1 s" } ],
     "path_settings": { "max_dist": 10 },
     "death_function": [ "MELT" ],
     "flags": [
@@ -526,7 +526,7 @@
     "vision_night": 50,
     "harvest": "exempt",
     "special_attacks": [ [ "TINDALOS_TELEPORT", 5 ], [ "DISAPPEAR", 25 ] ],
-    "emit_fields": [ "emit_tindalos_gas_leak" ],
+    "emit_fields": [ { "emit_id": "emit_tindalos_gas_leak", "delay": "1 s" } ],
     "path_settings": { "max_dist": 10 },
     "death_function": [ "MELT" ],
     "flags": [
diff --git a/data/json/monsters/zed_electric.json b/data/json/monsters/zed_electric.json
index d18d60ce96ae8..55894aad0f20e 100644
--- a/data/json/monsters/zed_electric.json
+++ b/data/json/monsters/zed_electric.json
@@ -120,7 +120,7 @@
     "vision_night": 3,
     "luminance": 16,
     "harvest": "CBM_SUBS",
-    "emit_fields": [ "emit_shock_cloud" ],
+    "emit_fields": [ { "emit_id": "emit_shock_cloud", "delay": "1 s" } ],
     "special_when_hit": [ "ZAPBACK", 75 ],
     "death_drops": "default_zombie_death_drops",
     "death_function": [ "NORMAL" ],
diff --git a/data/json/monsters/zed_explosive.json b/data/json/monsters/zed_explosive.json
index 11750b3a20aa4..f77a004ea5bd5 100644
--- a/data/json/monsters/zed_explosive.json
+++ b/data/json/monsters/zed_explosive.json
@@ -157,7 +157,7 @@
     "melee_cut": 0,
     "vision_night": 3,
     "harvest": "exempt",
-    "emit_fields": [ "emit_toxic_leak" ],
+    "emit_fields": [ { "emit_id": "emit_toxic_leak", "delay": "1 s" } ],
     "special_attacks": [ [ "SUICIDE", 20 ], [ "scratch", 15 ] ],
     "death_drops": "default_zombie_items",
     "death_function": [ "GAS" ],
diff --git a/data/json/monsters/zed_misc.json b/data/json/monsters/zed_misc.json
index 67a8f5493cc88..25de114cd86bb 100644
--- a/data/json/monsters/zed_misc.json
+++ b/data/json/monsters/zed_misc.json
@@ -1017,7 +1017,7 @@
     "vision_day": 50,
     "vision_night": 3,
     "harvest": "exempt",
-    "emit_fields": [ "emit_smoke_stream" ],
+    "emit_fields": [ { "emit_id": "emit_smoke_stream", "delay": "1 s" } ],
     "special_attacks": [ { "type": "bite", "cooldown": 5 }, [ "scratch", 15 ] ],
     "death_function": [ "SMOKEBURST" ],
     "flags": [
diff --git a/data/mods/CrazyCataclysm/crazy_monsters.json b/data/mods/CrazyCataclysm/crazy_monsters.json
index f3d87a6d0a7d1..455fa6fd3647e 100644
--- a/data/mods/CrazyCataclysm/crazy_monsters.json
+++ b/data/mods/CrazyCataclysm/crazy_monsters.json
@@ -98,7 +98,7 @@
     "armor_cut": 4,
     "vision_day": 30,
     "vision_night": 10,
-    "emit_fields": [ "emit_smoke_stream" ],
+    "emit_fields": [ { "emit_id": "emit_smoke_stream", "delay": "1 s" } ],
     "special_attacks": [ { "type": "bite", "cooldown": 5 } ],
     "anger_triggers": [ "HURT", "PLAYER_CLOSE" ],
     "placate_triggers": [ "MEAT" ],
diff --git a/data/mods/Magiclysm/monsters/dragon.json b/data/mods/Magiclysm/monsters/dragon.json
index 491d65f515bef..351bcde817762 100644
--- a/data/mods/Magiclysm/monsters/dragon.json
+++ b/data/mods/Magiclysm/monsters/dragon.json
@@ -155,7 +155,7 @@
     "//": "Large means powerful, but it does not mean fast.",
     "speed": 100,
     "delete": { "flags": [ "PATH_AVOID_DANGER_2" ] },
-    "emit_fields": [ "emit_dragon_adult_fright" ],
+    "emit_fields": [ { "emit_id": "emit_dragon_adult_fright", "delay": "1 s" } ],
     "special_attacks": [
       { "type": "bite", "cooldown": 10 },
       [ "scratch", 3 ],
diff --git a/data/mods/Modular_Turrets/monster_override.json b/data/mods/Modular_Turrets/monster_override.json
index 229fe875507a2..96658ff66b73a 100644
--- a/data/mods/Modular_Turrets/monster_override.json
+++ b/data/mods/Modular_Turrets/monster_override.json
@@ -170,7 +170,7 @@
     "copy-from": "mon_defbot_base",
     "name": "riotcontrol robot",
     "description": "An automated defense robot still active due to its internal power source.  This one is equipped with an electric prod, tear gas sprayer, and integrated 40mm beanbag launcher.",
-    "emit_fields": [ "emit_tear_gas_pulse" ],
+    "emit_fields": [ { "emit_id": "emit_tear_gas_pulse", "delay": "1 s" } ],
     "melee_damage": [ { "damage_type": "electric", "amount": 6 } ],
     "starting_ammo": { "40x46mm_m1006": 100 },
     "special_attacks": [
diff --git a/data/mods/My_Sweet_Cataclysm/sweet_monsters.json b/data/mods/My_Sweet_Cataclysm/sweet_monsters.json
index f4e0d87c30632..b1e66b30d73e8 100644
--- a/data/mods/My_Sweet_Cataclysm/sweet_monsters.json
+++ b/data/mods/My_Sweet_Cataclysm/sweet_monsters.json
@@ -369,7 +369,7 @@
     "vision_day": 5,
     "vision_night": 5,
     "harvest": "gum_spider",
-    "emit_fields": [ "emit_gum_web" ],
+    "emit_fields": [ { "emit_id": "emit_gum_web", "delay": "30 m" } ],
     "death_function": [ "NORMAL" ],
     "flags": [ "SEES", "SMELLS", "HEARS", "CLIMBS", "PATH_AVOID_FIRE", "PATH_AVOID_FALL" ],
     "reproduction": { "baby_egg": "gum", "baby_count": 10, "baby_timer": 5 }
diff --git a/data/mods/Salvaged_Robots/monsters.json b/data/mods/Salvaged_Robots/monsters.json
index 247708b5d115b..112510c8afc32 100644
--- a/data/mods/Salvaged_Robots/monsters.json
+++ b/data/mods/Salvaged_Robots/monsters.json
@@ -140,7 +140,7 @@
     "morale": 10,
     "dodge": 8,
     "armor_cut": 4,
-    "emit_fields": [ "emit_sparks" ],
+    "emit_fields": [ { "emit_id": "emit_sparks", "delay": "1 s" } ],
     "revert_to_itype": "bot_distract_hack",
     "death_function": [ "MELT" ],
     "special_attacks": [ [ "PARROT", 0 ] ],
@@ -160,7 +160,7 @@
     "aggression": 10,
     "morale": 0,
     "dodge": 4,
-    "emit_fields": [ "emit_fire_plume" ],
+    "emit_fields": [ { "emit_id": "emit_fire_plume", "delay": "1 s" } ],
     "death_function": [ "MELT" ],
     "extend": { "flags": [ "STUMBLES", "HARDTOSHOOT", "PET_WONT_FOLLOW", "FIREY" ] }
   },
@@ -243,7 +243,7 @@
     "description": "A salvaged eyebot repurposed into a floating space heater.  It emits a constant jet of warm air to heat an enclosed space.",
     "revert_to_itype": "bot_eyebot_heater",
     "fear_triggers": [ "HURT" ],
-    "emit_fields": [ "emit_hot_air2_stream" ],
+    "emit_fields": [ { "emit_id": "emit_hot_air2_stream", "delay": "1 s" } ],
     "extend": { "flags": [ "PET_WONT_FOLLOW", "WARM" ] }
   },
   {
@@ -410,7 +410,7 @@
     "morale": 10,
     "fear_triggers": [ "HURT" ],
     "revert_to_itype": "bot_utilibot_digester",
-    "emit_fields": [ "emit_acid_trail" ],
+    "emit_fields": [ { "emit_id": "emit_acid_trail", "delay": "1 s" } ],
     "extend": { "flags": [ "STUMBLES", "ABSORBS", "ACIDPROOF" ] }
   },
   {
@@ -533,7 +533,7 @@
     "description": "A salvaged medibot stuffed with marijuana, covered in multicolored blinking lights, and programmed to dance.  Why on Earth would you build this crazy thing?",
     "color": "yellow",
     "luminance": 100,
-    "emit_fields": [ "emit_weed_puff" ],
+    "emit_fields": [ { "emit_id": "emit_weed_puff", "delay": "1 s" } ],
     "melee_skill": 4,
     "melee_dice": 2,
     "melee_dice_sides": 4,
@@ -1205,7 +1205,7 @@
     "vision_day": 20,
     "revert_to_itype": "bot_defbot_samurai",
     "special_when_hit": [ "ZAPBACK", 5 ],
-    "emit_fields": [ "emit_electric_arcs" ],
+    "emit_fields": [ { "emit_id": "emit_electric_arcs", "delay": "1 s" } ],
     "extend": { "flags": [ "ELECTRIC" ] }
   },
   {
@@ -1229,7 +1229,7 @@
     "dodge": 3,
     "vision_day": 50,
     "revert_to_itype": "bot_defbot_paladin",
-    "emit_fields": [ "emit_smoke_trail" ],
+    "emit_fields": [ { "emit_id": "emit_smoke_trail", "delay": "1 s" } ],
     "starting_ammo": { "gasoline": 1000 },
     "special_attacks": [
       [ "PARROT", 0 ],
@@ -1368,7 +1368,7 @@
     "luminance": 200,
     "armor_bash": 8,
     "revert_to_itype": "bot_advbot_glitter",
-    "emit_fields": [ "emit_dazzle_trail" ],
+    "emit_fields": [ { "emit_id": "emit_dazzle_trail", "delay": "1 s" } ],
     "special_attacks": [
       {
         "type": "gun",
@@ -1397,7 +1397,7 @@
     "melee_damage": [ { "damage_type": "acid", "amount": 8 } ],
     "armor_bash": 8,
     "armor_cut": 8,
-    "emit_fields": [ "emit_acid_trail" ],
+    "emit_fields": [ { "emit_id": "emit_acid_trail", "delay": "1 s" } ],
     "special_when_hit": [ "ACIDSPLASH", 100 ],
     "special_attacks": [
       [ "ACID_BARF", 10 ],
@@ -1588,7 +1588,7 @@
     "attack_effs": [ { "id": "downed", "chance": 20, "duration": 10 }, { "id": "irradiated", "chance": 50 } ],
     "vision_day": 20,
     "revert_to_itype": "bot_tankbot_sultan",
-    "emit_fields": [ "emit_nuclear_trail" ],
+    "emit_fields": [ { "emit_id": "emit_nuclear_trail", "delay": "1 s" } ],
     "special_attacks": [ [ "SMASH", 30 ], [ "GRAB", 20 ] ],
     "extend": { "flags": [ "STUMBLES", "GRABS" ] }
   }
diff --git a/doc/MONSTERS.md b/doc/MONSTERS.md
index a2798f3ad60b7..54c725f0ee0bd 100644
--- a/doc/MONSTERS.md
+++ b/doc/MONSTERS.md
@@ -234,6 +234,12 @@ An item group that is used to spawn items when the monster dies. This can be an
 
 How the monster behaves on death. See JSON_FLAGS.md for a list of possible functions. One can add or remove entries in mods via "add:death_function" and "remove:death_function".
 
+## "emit_field"
+(array of objects of emit_id and time_duration, optional)
+"emit_fields": [ { "emit_id": "emit_gum_web", "delay": "30 m" } ],
+
+What field the monster emits and how often it does so. Time duration can use strings: "1 h", "60 m", "3600 s" etc...
+
 ## "regenerates"
 (integer, optional)
 
diff --git a/src/monster.cpp b/src/monster.cpp
index 1a1594433b278..1cb0502b09473 100644
--- a/src/monster.cpp
+++ b/src/monster.cpp
@@ -1941,8 +1941,12 @@ void monster::process_turn()
 {
     decrement_summon_timer();
     if( !is_hallucination() ) {
-        for( const auto &e : type->emit_fields ) {
-            if( e == emit_id( "emit_shock_cloud" ) ) {
+        for( const std::pair<emit_id, time_duration> &e : type->emit_fields ) {
+            if( !calendar::once_every( e.second ) ) {
+                continue;
+            }
+            const emit_id emid = e.first;
+            if( emid == emit_id( "emit_shock_cloud" ) ) {
                 if( has_effect( effect_emp ) ) {
                     continue; // don't emit electricity while EMPed
                 } else if( has_effect( effect_supercharged ) ) {
@@ -1950,7 +1954,7 @@ void monster::process_turn()
                     continue;
                 }
             }
-            g->m.emit_field( pos(), e );
+            g->m.emit_field( pos(), emid );
         }
     }
 
diff --git a/src/monstergenerator.cpp b/src/monstergenerator.cpp
index 7fc39dfbb71ab..6206c3e7e1aba 100644
--- a/src/monstergenerator.cpp
+++ b/src/monstergenerator.cpp
@@ -760,7 +760,20 @@ void mtype::load( const JsonObject &jo, const std::string &src )
         dies.push_back( mdeath::normal );
     }
 
-    assign( jo, "emit_fields", emit_fields );
+    if( jo.has_array( "emit_fields" ) ) {
+        JsonArray jar = jo.get_array( "emit_fields" );
+        if( jar.has_string( 0 ) ) { // TEMPORARY until 0.F
+            for( const std::string id : jar ) {
+                emit_fields.emplace( emit_id( id ), 1_seconds );
+            }
+        } else {
+            while( jar.has_more() ) {
+                JsonObject obj = jar.next_object();
+                emit_fields.emplace( emit_id( obj.get_string( "emit_id" ) ),
+                                     read_from_json_string<time_duration>( *obj.get_raw( "delay" ), time_duration::units ) );
+            }
+        }
+    }
 
     if( jo.has_member( "special_when_hit" ) ) {
         JsonArray jsarr = jo.get_array( "special_when_hit" );
@@ -1149,9 +1162,10 @@ void MonsterGenerator::check_monster_definitions() const
             }
         }
 
-        for( const auto &e : mon.emit_fields ) {
-            if( !e.is_valid() ) {
-                debugmsg( "monster %s has invalid emit source %s", mon.id.c_str(), e.c_str() );
+        for( const std::pair<emit_id, time_duration> &e : mon.emit_fields ) {
+            const emit_id emid = e.first;
+            if( !emid.is_valid() ) {
+                debugmsg( "monster %s has invalid emit source %s", mon.id.c_str(), emid.c_str() );
             }
         }
 
diff --git a/src/mtype.h b/src/mtype.h
index d28bc9f100be2..c3fd06ee887d2 100644
--- a/src/mtype.h
+++ b/src/mtype.h
@@ -353,7 +353,7 @@ struct mtype {
         int mech_str_bonus = 0;
 
         /** Emission sources that cycle each turn the monster remains alive */
-        std::set<emit_id> emit_fields;
+        std::map<emit_id, time_duration> emit_fields;
 
         pathfinding_settings path_settings;