Silly me

code/modules/atmospherics/gasmixtures/gas_types.dm

@@ -7,6 +7,7 @@ GLOBAL_LIST_INIT(nonreactive_gases, typecacheof(list(/datum/gas/oxygen, /datum/g
 	for(var/gas_path in .)
 		var/list/gas_info = new(11)
 		var/datum/gas/gas = gas_path
+		var/datum/gas/instance = new(gas_path)
 
 		gas_info[META_GAS_SPECIFIC_HEAT] = initial(gas.specific_heat)
 		gas_info[META_GAS_NAME] = initial(gas.name)
@@ -20,7 +21,7 @@ GLOBAL_LIST_INIT(nonreactive_gases, typecacheof(list(/datum/gas/oxygen, /datum/g
 		gas_info[META_GAS_FUSION_POWER] = initial(gas.fusion_power)
 		gas_info[META_GAS_DANGER] = initial(gas.dangerous)
 		gas_info[META_GAS_ID] = initial(gas.id)
-		gas_info[META_GAS_BREATH_ALERT_INFO] = initial(gas.breath_alert_info)
+		gas_info[META_GAS_BREATH_ALERT_INFO] = instance.breath_alert_info.Copy()
 		gas_info[META_GAS_BREATH_REAGENT] = initial(gas.breath_reagent)
 		gas_info[META_GAS_BREATH_RESULTS] = initial(gas.breath_results)
 		gas_info[META_GAS_BREATH_REAGENT_DANGEROUS] = initial(gas.breath_reagent_dangerous)
@@ -54,7 +55,7 @@ GLOBAL_LIST_INIT(nonreactive_gases, typecacheof(list(/datum/gas/oxygen, /datum/g
 	var/dangerous = FALSE //currently used by canisters
 	var/fusion_power = 0 //How much the gas accelerates a fusion reaction
 	var/rarity = 0 // relative rarity compared to other gases, used when setting up the reactions list.
-	var/list/breath_alert_info = null
+	var/list/breath_alert_info = list()
 	var/breath_reagent = null
 	var/breath_results = null
 	var/breath_reagent_dangerous = null