Shamelessly steals HarpyEagle's code

code/modules/mob/living/carbon/breathe.dm

@@ -24,6 +24,11 @@
 		breath = get_breath_from_internal() //First, check for air from internals
 		if(!breath)
 			breath = get_breath_from_environment() //No breath from internals so let's try to get air from our location
+		if(!breath)
+			var/static/datum/gas_mixture/vacuum //avoid having to create a new gas mixture for each breath in space
+			if(!vacuum) vacuum = new
+
+			breath = vacuum //still nothing? must be vacuum
 
 	handle_breath(breath)
 	handle_post_breath(breath)

code/modules/mob/living/carbon/human/human.dm

@@ -928,9 +928,8 @@
 /mob/living/carbon/human/proc/rupture_lung()
 	var/obj/item/organ/internal/lungs/L = internal_organs_by_name[O_LUNGS]
 
-	if(L && !L.is_bruised())
+	if(L)
-		src.custom_pain("You feel a stabbing pain in your chest!", 1)
+		L.rupture()
-		L.damage = L.min_bruised_damage
 
 /*
 /mob/living/carbon/human/verb/simulate()

code/modules/mob/living/carbon/human/life.dm

@@ -332,6 +332,12 @@
 		adjustOxyLoss(-5)
 		return
 
+	if(should_have_organ(O_LUNGS))
+		var/obj/item/organ/internal/lungs/L = internal_organs_by_name[O_LUNGS]
+		if(breath.total_moles < BREATH_MOLES / 5 || breath.total_moles > BREATH_MOLES * 5)
+			if(!L.is_bruised() && prob(5))
+				rupture_lung()
+
 	if(!breath || (breath.total_moles == 0) || suiciding)
 		failed_last_breath = 1
 		if(suiciding)
@@ -343,9 +349,6 @@
 		else
 			adjustOxyLoss(HUMAN_CRIT_MAX_OXYLOSS)
 
-		if(prob(5))
-			rupture_lung()
-
 		oxygen_alert = max(oxygen_alert, 1)
 
 		return 0

code/modules/organs/internal/lungs.dm

@@ -23,4 +23,11 @@
 			owner.drip(10)
 		if(prob(4))
 			spawn owner.emote("me", 1, "gasps for air!")
-			owner.losebreath += 15
+			owner.losebreath += 15
+
+
+/obj/item/organ/internal/lungs/proc/rupture()
+	var/obj/item/organ/external/parent = owner.get_organ(parent_organ)
+	if(istype(parent))
+		owner.custom_pain("You feel a stabbing pain in your [parent.name]!", 1)
+	parent.bruise()

code/modules/organs/organ.dm

@@ -247,6 +247,9 @@ var/list/organ_cache = list()
 			if(parent && !silent)
 				owner.custom_pain("Something inside your [parent.name] hurts a lot.", 1)
 
+/obj/item/organ/proc/bruise()
+	damage = max(damage, min_bruised_damage)
+
 /obj/item/organ/proc/robotize() //Being used to make robutt hearts, etc
 	robotic = ORGAN_ROBOT
 	src.status &= ~ORGAN_BROKEN