Allows Plasma Fixation to heal in any amount of plasma gas (#65389)

Allows for a very small amount of healing if there's a non-visible amount of plasma in the atmosphere,

code/datums/diseases/advance/symptoms/heal.dm

@@ -453,6 +453,9 @@
 		return TRUE
 	return FALSE
 
+///Determines the rate at which Plasma Fixation heals based on the amount of plasma in the air
+#define HEALING_PER_MOL 1.1
+
 /datum/symptom/heal/plasma
 	name = "Plasma Fixation"
 	desc = "The virus draws plasma from the atmosphere and from inside the body to heal and stabilize body temperature."
@@ -488,10 +491,10 @@
 		environment = M.loc.return_air()
 	if(environment)
 		gases = environment.gases
-		if(gases[/datum/gas/plasma] && gases[/datum/gas/plasma][MOLES] > gases[/datum/gas/plasma][GAS_META][META_GAS_MOLES_VISIBLE]) //if there's enough plasma in the air to see
-			. += power * 0.5
+		if(gases[/datum/gas/plasma])
+			. += power * min(0.5, gases[/datum/gas/plasma][MOLES] * HEALING_PER_MOL)
 	if(M.reagents.has_reagent(/datum/reagent/toxin/plasma, needs_metabolizing = TRUE))
-		. += power * 0.75
+		. += power * 0.75 //Determines how much the symptom heals if injected or ingested
 
 /datum/symptom/heal/plasma/Heal(mob/living/carbon/M, datum/disease/advance/A, actual_power)
 	var/heal_amt = 4 * actual_power
@@ -521,6 +524,8 @@
 			M.update_damage_overlays()
 	return 1
 
+///Plasma End
+#undef HEALING_PER_MOL
 
 /datum/symptom/heal/radiation
 	name = "Radioactive Resonance"