diff --git a/code/datums/disease.dm b/code/datums/disease.dm
index 024337c8e065..a8fdf504fc07 100644
--- a/code/datums/disease.dm
+++ b/code/datums/disease.dm
@@ -104,16 +104,20 @@ GLOBAL_LIST_INIT(diseases, typesof(/datum/disease) - /datum/disease)
 		how_spread = force_spread
 
 	if(how_spread == SPECIAL || how_spread == NON_CONTAGIOUS || how_spread == BLOOD)//does not spread
-		return
+		return FALSE
 
 	if(stage < contagious_period) //the disease is not contagious at this stage
-		return
+		return FALSE
 
 	if(!source)//no holder specified
 		if(affected_mob)//no mob affected holder
 			source = affected_mob
 		else //no source and no mob affected. Rogue disease. Break
-			return
+			return FALSE
+
+	var/mob/source_mob = source
+	if(istype(source_mob) && !source_mob.can_pass_disease())
+		return FALSE
 
 	var/check_range = airborne_range//defaults to airborne - range 2
 
@@ -122,7 +126,7 @@ GLOBAL_LIST_INIT(diseases, typesof(/datum/disease) - /datum/disease)
 
 	if(isturf(source.loc))
 		for(var/mob/living/carbon/victim in oview(check_range, source))
-			if(isturf(victim.loc))
+			if(isturf(victim.loc) && victim.can_pass_disease())
 				if(AStar(source.loc, victim.loc, /turf/proc/AdjacentTurfs, /turf/proc/Distance, check_range))
 					victim.contract_disease(src, 0, 1, force_spread)
 
diff --git a/code/game/objects/structures/crates_lockers/closets/l3closet.dm b/code/game/objects/structures/crates_lockers/closets/l3closet.dm
index fa5332c0c996..723483104844 100644
--- a/code/game/objects/structures/crates_lockers/closets/l3closet.dm
+++ b/code/game/objects/structures/crates_lockers/closets/l3closet.dm
@@ -1,27 +1,25 @@
 /obj/structure/closet/l3closet
 	name = "level-3 biohazard suit closet"
 	desc = "It's a storage unit for level-3 biohazard gear."
-	icon_state = "bio"
-	icon_closed = "bio"
-	icon_opened = "bioopen"
+	icon_state = "bio_general"
+	icon_closed = "bio_general"
+	icon_opened = "bio_generalopen"
 
 /obj/structure/closet/l3closet/Initialize()
 	. = ..()
-	new /obj/item/clothing/suit/bio_suit/general( src )
-	new /obj/item/clothing/head/bio_hood/general( src )
+	new /obj/item/clothing/suit/bio_suit( src )
+	new /obj/item/clothing/head/bio_hood( src )
 
+/obj/structure/closet/l3closet/medical
+	icon_state = "bio"
+	icon_closed = "bio"
+	icon_opened = "bioopen"
 
-/obj/structure/closet/l3closet/general
-	icon_state = "bio_general"
-	icon_closed = "bio_general"
-	icon_opened = "bio_generalopen"
-
-/obj/structure/closet/l3closet/general/Initialize()
+/obj/structure/closet/l3closet/medical/Initialize()
 	. = ..()
 	contents = list()
-	new /obj/item/clothing/suit/bio_suit/general( src )
-	new /obj/item/clothing/head/bio_hood/general( src )
-
+	new /obj/item/clothing/suit/bio_suit/medical( src )
+	new /obj/item/clothing/head/bio_hood/medical( src )
 
 /obj/structure/closet/l3closet/virology
 	icon_state = "bio_virology"
@@ -33,9 +31,6 @@
 	contents = list()
 	new /obj/item/clothing/suit/bio_suit/virology( src )
 	new /obj/item/clothing/head/bio_hood/virology( src )
-	new /obj/item/clothing/mask/breath(src)
-	new /obj/item/tank/oxygen(src)
-
 
 /obj/structure/closet/l3closet/security
 	icon_state = "bio_security"
@@ -48,19 +43,6 @@
 	new /obj/item/clothing/suit/bio_suit/security( src )
 	new /obj/item/clothing/head/bio_hood/security( src )
 
-
-/obj/structure/closet/l3closet/janitor
-	icon_state = "bio_janitor"
-	icon_closed = "bio_janitor"
-	icon_opened = "bio_janitoropen"
-
-/obj/structure/closet/l3closet/janitor/Initialize()
-	. = ..()
-	contents = list()
-	new /obj/item/clothing/suit/bio_suit/janitor( src )
-	new /obj/item/clothing/head/bio_hood/janitor( src )
-
-
 /obj/structure/closet/l3closet/scientist
 	icon_state = "bio_scientist"
 	icon_closed = "bio_scientist"
diff --git a/code/modules/clothing/head/helmet.dm b/code/modules/clothing/head/helmet.dm
index 53e96f898613..2fbccc4a21cc 100644
--- a/code/modules/clothing/head/helmet.dm
+++ b/code/modules/clothing/head/helmet.dm
@@ -1443,7 +1443,7 @@ GLOBAL_LIST_INIT(allowed_helmet_items, list(
 	armor_rad = CLOTHING_ARMOR_HIGHPLUS
 	force = 0 //"The M3 MOPP mask would be a normal weapon if you were to hit someone with it."
 	throwforce = 0
-	flags_inventory = BLOCKSHARPOBJ
+	flags_inventory = BLOCKSHARPOBJ|BLOCKGASEFFECT
 	flags_marine_helmet = NO_FLAGS
 	flags_atom = NO_SNOW_TYPE|NO_NAME_OVERRIDE
 	flags_inv_hide = HIDEEARS|HIDEALLHAIR
diff --git a/code/modules/clothing/suits/bio.dm b/code/modules/clothing/suits/bio.dm
index 59e0918550ed..d57dd4ea5c8b 100644
--- a/code/modules/clothing/suits/bio.dm
+++ b/code/modules/clothing/suits/bio.dm
@@ -1,7 +1,9 @@
 //Biosuit complete with shoes (in the item sprite)
+//Standard biosuit, orange stripe
+
 /obj/item/clothing/head/bio_hood
 	name = "bio hood"
-	icon_state = "bio"
+	icon_state = "bio_general"
 	desc = "A hood that protects the head and face from biological contaminants."
 	permeability_coefficient = 0.2
 	armor_melee = CLOTHING_ARMOR_NONE
@@ -12,7 +14,7 @@
 	armor_bio = CLOTHING_ARMOR_ULTRAHIGH
 	armor_rad = CLOTHING_ARMOR_MEDIUM
 	armor_internaldamage = CLOTHING_ARMOR_LOW
-	flags_inventory = COVEREYES|COVERMOUTH
+	flags_inventory = COVEREYES|COVERMOUTH|BLOCKGASEFFECT
 	flags_inv_hide = HIDEFACE|HIDEMASK|HIDEEARS|HIDEALLHAIR
 	flags_armor_protection = BODY_FLAG_HEAD|BODY_FLAG_FACE|BODY_FLAG_EYES
 	siemens_coefficient = 0.9
@@ -26,7 +28,7 @@
 /obj/item/clothing/suit/bio_suit
 	name = "bio suit"
 	desc = "A suit that protects against biological contamination."
-	icon_state = "bio"
+	icon_state = "bio_general"
 	item_state = "bio_suit"
 	w_class = SIZE_LARGE//bulky item
 	gas_transfer_coefficient = 0.01
@@ -47,7 +49,7 @@
 /obj/item/clothing/suit/storage/synthbio
 	name = "bio suit"
 	desc = "Synthetic compliant bio-hazard suit. Intended to allow a synthetic to offer the illusion of infection control to humans. Has had most of the internal protective lining removed, allowing it to hold equipment and be lighter to move in."
-	icon_state = "bio"
+	icon_state = "bio_general"
 	item_state = "bio_suit"
 	allowed = list(
 		/obj/item/weapon/baton,
@@ -65,13 +67,13 @@
 		/obj/item/device/motiondetector,
 	)
 
-//Standard biosuit, orange stripe
-/obj/item/clothing/head/bio_hood/general
-	icon_state = "bio_general"
+//Medical biosuit, blue wrist bands
+/obj/item/clothing/head/bio_hood/medical
+	icon_state = "bio_med"
 	flags_armor_protection = BODY_FLAG_HEAD|BODY_FLAG_FACE|BODY_FLAG_EYES
 
-/obj/item/clothing/suit/bio_suit/general
-	icon_state = "bio_general"
+/obj/item/clothing/suit/bio_suit/medical
+	icon_state = "bio_med"
 	flags_armor_protection = BODY_FLAG_CHEST|BODY_FLAG_GROIN|BODY_FLAG_LEGS|BODY_FLAG_ARMS|BODY_FLAG_HANDS|BODY_FLAG_FEET
 	flags_inv_hide = HIDEGLOVES|HIDEJUMPSUIT|HIDETAIL
 
@@ -84,7 +86,7 @@
 	flags_armor_protection = BODY_FLAG_CHEST|BODY_FLAG_GROIN|BODY_FLAG_LEGS|BODY_FLAG_ARMS
 	flags_inv_hide = HIDEGLOVES|HIDEJUMPSUIT|HIDETAIL
 
-//Security biosuit, grey with red stripe across the chest
+//Security biosuit, red wrist bands
 /obj/item/clothing/head/bio_hood/security
 	icon_state = "bio_security"
 
@@ -93,17 +95,7 @@
 	flags_armor_protection = BODY_FLAG_CHEST|BODY_FLAG_GROIN|BODY_FLAG_LEGS|BODY_FLAG_ARMS
 	flags_inv_hide = HIDEGLOVES|HIDEJUMPSUIT|HIDETAIL
 
-//Janitor's biosuit, grey with purple arms
-/obj/item/clothing/head/bio_hood/janitor
-	icon_state = "bio_janitor"
-
-/obj/item/clothing/suit/bio_suit/janitor
-	icon_state = "bio_janitor"
-	flags_armor_protection = BODY_FLAG_CHEST|BODY_FLAG_GROIN|BODY_FLAG_LEGS|BODY_FLAG_ARMS
-	flags_inv_hide = HIDEGLOVES|HIDEJUMPSUIT|HIDETAIL
-
-
-//Scientist's biosuit, white with a pink-ish hue
+//Scientist's biosuit, purple wrist bands
 /obj/item/clothing/head/bio_hood/scientist
 	icon_state = "bio_scientist"
 
@@ -112,15 +104,6 @@
 	flags_armor_protection = BODY_FLAG_CHEST|BODY_FLAG_GROIN|BODY_FLAG_LEGS|BODY_FLAG_ARMS
 	flags_inv_hide = HIDEGLOVES|HIDEJUMPSUIT|HIDETAIL
 
-//CMO's biosuit, blue stripe
-/obj/item/clothing/suit/bio_suit/cmo
-	icon_state = "bio_cmo"
-	flags_armor_protection = BODY_FLAG_CHEST|BODY_FLAG_GROIN|BODY_FLAG_LEGS|BODY_FLAG_ARMS
-	flags_inv_hide = HIDEGLOVES|HIDEJUMPSUIT|HIDETAIL
-
-/obj/item/clothing/head/bio_hood/cmo
-	icon_state = "bio_cmo"
-
 
 //Plague Dr mask can be found in clothing/masks/gasmask.dm
 /obj/item/clothing/suit/bio_suit/plaguedoctorsuit
diff --git a/code/modules/gear_presets/synths.dm b/code/modules/gear_presets/synths.dm
index 9a181c817020..1bd8bac6b5c1 100644
--- a/code/modules/gear_presets/synths.dm
+++ b/code/modules/gear_presets/synths.dm
@@ -212,14 +212,14 @@
 /datum/equipment_preset/synth/survivor/scientist_synth
 	name = "Survivor - Synthetic - Scientist Synth"
 	equipment_to_spawn = list(
-		WEAR_HEAD = /obj/item/clothing/head/bio_hood,
+		WEAR_HEAD = /obj/item/clothing/head/bio_hood/synth,
 		WEAR_FACE = /obj/item/clothing/mask/surgical,
 		WEAR_EYES = /obj/item/clothing/glasses/hud/health,
 		WEAR_BODY = /obj/item/clothing/under/rank/scientist,
 		WEAR_BACK = /obj/item/storage/backpack/satchel/chem,
 		WEAR_IN_BACK = /obj/item/reagent_container/glass/beaker/vial/random/good,
 		WEAR_IN_BACK = /obj/item/paper/research_notes/good,
-		WEAR_JACKET = /obj/item/clothing/suit/bio_suit,
+		WEAR_JACKET = /obj/item/clothing/suit/storage/synthbio,
 		WEAR_WAIST = /obj/item/storage/belt/medical/lifesaver/full,
 		WEAR_HANDS = /obj/item/clothing/gloves/black,
 		WEAR_R_HAND = /obj/item/device/motiondetector,
diff --git a/code/modules/mob/living/carbon/carbon.dm b/code/modules/mob/living/carbon/carbon.dm
index 08daa5348022..1ee7cc4c3169 100644
--- a/code/modules/mob/living/carbon/carbon.dm
+++ b/code/modules/mob/living/carbon/carbon.dm
@@ -156,30 +156,66 @@
 
 	. = ..()
 
-/mob/living/carbon/attack_hand(mob/M as mob)
-	if(!istype(M, /mob/living/carbon)) return
+/mob/living/carbon/attack_hand(mob/target_mob as mob)
+	if(!istype(target_mob, /mob/living/carbon)) return
 
-	if(M.mob_flags & SURGERY_MODE_ON && M.a_intent & (INTENT_HELP|INTENT_DISARM))
-		var/datum/surgery/current_surgery = active_surgeries[M.zone_selected]
+	if(target_mob.mob_flags & SURGERY_MODE_ON && target_mob.a_intent & (INTENT_HELP|INTENT_DISARM))
+		var/datum/surgery/current_surgery = active_surgeries[target_mob.zone_selected]
 		if(current_surgery)
-			if(current_surgery.attempt_next_step(M, null))
+			if(current_surgery.attempt_next_step(target_mob, null))
 				return TRUE
 		else
-			var/obj/limb/affecting = get_limb(check_zone(M.zone_selected))
-			if(affecting && initiate_surgery_moment(null, src, affecting, M))
+			var/obj/limb/affecting = get_limb(check_zone(target_mob.zone_selected))
+			if(affecting && initiate_surgery_moment(null, src, affecting, target_mob))
 				return TRUE
 
-	for(var/datum/disease/D in viruses)
-		if(D.spread_by_touch())
-			M.contract_disease(D, 0, 1, CONTACT_HANDS)
+	if(can_pass_disease() && target_mob.can_pass_disease())
+		for(var/datum/disease/virus in viruses)
+			if(virus.spread_by_touch())
+				target_mob.contract_disease(virus, 0, 1, CONTACT_HANDS)
 
-	for(var/datum/disease/D in M.viruses)
-		if(D.spread_by_touch())
-			contract_disease(D, 0, 1, CONTACT_HANDS)
+		for(var/datum/disease/virus in target_mob.viruses)
+			if(virus.spread_by_touch())
+				contract_disease(virus, 0, 1, CONTACT_HANDS)
 
-	M.next_move += 7 //Adds some lag to the 'attack'. Adds up to 11 in combination with click_adjacent.
+	target_mob.next_move += 7 //Adds some lag to the 'attack'. Adds up to 11 in combination with click_adjacent.
 	return
 
+/// Whether or not a mob can pass diseases to another, or receive said diseases.
+/mob/proc/can_pass_disease()
+	return TRUE
+
+/mob/living/carbon/human/can_pass_disease()
+	/// Multiplier for checked pieces.
+	var/mult = 0
+	/// Total amount of bio protection
+	var/total_prot = 0
+	/// Super bio armor
+	var/bio_hardcore = 0
+
+	var/list/worn_clothes = list()
+	worn_clothes += head
+	worn_clothes += wear_suit
+	worn_clothes += hands
+	worn_clothes += glasses
+	worn_clothes += w_uniform
+	worn_clothes += shoes
+	worn_clothes += wear_mask
+
+	for(var/obj/item/clothing/worn_item in worn_clothes)
+		total_prot = (total_prot + worn_item.armor_bio)
+		mult++
+		if(worn_item.armor_bio == CLOTHING_ARMOR_HARDCORE)
+			bio_hardcore++
+
+	if(bio_hardcore >= 2)
+		return FALSE
+
+	var/perc = (total_prot / mult)
+	if(!prob(perc))
+		return TRUE
+	return FALSE
+
 /mob/living/carbon/electrocute_act(shock_damage, obj/source, siemens_coeff = 1.0, def_zone = null)
 	if(status_flags & GODMODE) //godmode
 		return FALSE
diff --git a/icons/mob/humans/onmob/head_0.dmi b/icons/mob/humans/onmob/head_0.dmi
index 9fc0bc82c123..b4738019fe1a 100644
Binary files a/icons/mob/humans/onmob/head_0.dmi and b/icons/mob/humans/onmob/head_0.dmi differ
diff --git a/icons/mob/humans/onmob/suit_0.dmi b/icons/mob/humans/onmob/suit_0.dmi
index 737b59f6c4af..f2c4305f9cba 100644
Binary files a/icons/mob/humans/onmob/suit_0.dmi and b/icons/mob/humans/onmob/suit_0.dmi differ
diff --git a/icons/obj/items/clothing/hats.dmi b/icons/obj/items/clothing/hats.dmi
index 3e2a1dcfc243..fe95f09af4c8 100644
Binary files a/icons/obj/items/clothing/hats.dmi and b/icons/obj/items/clothing/hats.dmi differ
diff --git a/icons/obj/items/clothing/suits.dmi b/icons/obj/items/clothing/suits.dmi
index 5057a89fe278..f3509d470376 100644
Binary files a/icons/obj/items/clothing/suits.dmi and b/icons/obj/items/clothing/suits.dmi differ
diff --git a/maps/map_files/BigRed/BigRed.dmm b/maps/map_files/BigRed/BigRed.dmm
index dbcf22e2e586..bd4c1b4f33d8 100644
--- a/maps/map_files/BigRed/BigRed.dmm
+++ b/maps/map_files/BigRed/BigRed.dmm
@@ -13123,7 +13123,7 @@
 	},
 /area/bigredv2/outside/virology)
 "aNa" = (
-/obj/structure/closet/l3closet/general,
+/obj/structure/closet/l3closet/virology,
 /turf/open/floor{
 	icon_state = "white"
 	},
diff --git a/maps/map_files/CORSAT/Corsat.dmm b/maps/map_files/CORSAT/Corsat.dmm
index 9c09a95e9f94..a0f2d17b69c0 100644
--- a/maps/map_files/CORSAT/Corsat.dmm
+++ b/maps/map_files/CORSAT/Corsat.dmm
@@ -31121,7 +31121,7 @@
 	},
 /area/corsat/omega/maint)
 "bLD" = (
-/obj/structure/closet/l3closet/janitor,
+/obj/structure/closet/l3closet,
 /turf/open/floor/corsat{
 	dir = 5;
 	icon_state = "yellow"
@@ -35244,7 +35244,7 @@
 /turf/open/floor/corsat,
 /area/corsat/inaccessible)
 "bYU" = (
-/obj/structure/closet/l3closet/general,
+/obj/structure/closet/l3closet,
 /turf/open/floor/corsat{
 	icon_state = "yellow"
 	},
@@ -39429,7 +39429,7 @@
 /turf/open/gm/dirtgrassborder/north,
 /area/corsat/theta/biodome)
 "ePL" = (
-/obj/structure/closet/l3closet/general,
+/obj/structure/closet/l3closet,
 /turf/open/floor/corsat{
 	icon_state = "plate"
 	},
@@ -58094,7 +58094,7 @@
 	},
 /area/corsat/gamma/hangar/flightcontrol)
 "sFD" = (
-/obj/structure/closet/l3closet/general,
+/obj/structure/closet/l3closet,
 /obj/structure/machinery/light,
 /turf/open/floor/corsat{
 	icon_state = "plate"
diff --git a/maps/map_files/FOP_v3_Sciannex/Fiorina_SciAnnex.dmm b/maps/map_files/FOP_v3_Sciannex/Fiorina_SciAnnex.dmm
index f81f67e45a80..40a5a4349435 100644
--- a/maps/map_files/FOP_v3_Sciannex/Fiorina_SciAnnex.dmm
+++ b/maps/map_files/FOP_v3_Sciannex/Fiorina_SciAnnex.dmm
@@ -13504,9 +13504,8 @@
 /area/fiorina/station/botany)
 "igQ" = (
 /obj/structure/closet/cabinet,
-/obj/item/clothing/under/rank/janitor,
-/obj/item/clothing/suit/bio_suit/janitor,
-/obj/item/clothing/head/bio_hood/janitor,
+/obj/item/clothing/suit/bio_suit,
+/obj/item/clothing/head/bio_hood,
 /turf/open/floor/wood,
 /area/fiorina/station/civres_blue)
 "igV" = (
@@ -14854,7 +14853,7 @@
 	},
 /area/fiorina/station/civres_blue)
 "iXV" = (
-/obj/structure/closet/l3closet/general,
+/obj/structure/closet/l3closet,
 /turf/open/floor/prison,
 /area/fiorina/tumor/aux_engi)
 "iYa" = (
@@ -30983,10 +30982,6 @@
 /area/fiorina/tumor/civres)
 "sQr" = (
 /obj/structure/janitorialcart,
-/obj/item/clothing/head/bio_hood/janitor{
-	pixel_x = -4;
-	pixel_y = 5
-	},
 /turf/open/floor/prison,
 /area/fiorina/station/disco)
 "sQy" = (
diff --git a/maps/map_files/USS_Almayer/USS_Almayer.dmm b/maps/map_files/USS_Almayer/USS_Almayer.dmm
index 9e1d1ee91c96..f86f7d26290a 100644
--- a/maps/map_files/USS_Almayer/USS_Almayer.dmm
+++ b/maps/map_files/USS_Almayer/USS_Almayer.dmm
@@ -17029,7 +17029,7 @@
 	},
 /area/almayer/shipboard/port_point_defense)
 "bVe" = (
-/obj/structure/closet/l3closet/general,
+/obj/structure/closet/l3closet/scientist,
 /obj/structure/window/reinforced{
 	dir = 8;
 	health = 80
@@ -44945,7 +44945,7 @@
 /turf/open/floor/plating/plating_catwalk,
 /area/almayer/maint/hull/upper/u_a_s)
 "lmw" = (
-/obj/structure/closet/l3closet/general,
+/obj/structure/closet/l3closet/scientist,
 /obj/structure/machinery/light{
 	dir = 8
 	},
@@ -51494,7 +51494,7 @@
 /turf/open/floor/almayer,
 /area/almayer/hallways/lower/starboard_umbilical)
 "nDo" = (
-/obj/structure/closet/l3closet/general,
+/obj/structure/closet/l3closet/scientist,
 /obj/structure/window/reinforced{
 	dir = 8;
 	health = 80