diff --git a/code/__DEFINES/atmospherics.dm b/code/__DEFINES/atmospherics.dm
index 0e3aa1a6ff..d22d144acd 100644
--- a/code/__DEFINES/atmospherics.dm
+++ b/code/__DEFINES/atmospherics.dm
@@ -148,10 +148,10 @@
 #define CANVERTICALATMOSPASS(A, O) ( A.CanAtmosPassVertical == ATMOS_PASS_PROC ? A.CanAtmosPass(O, TRUE) : ( A.CanAtmosPassVertical == ATMOS_PASS_DENSITY ? !A.density : A.CanAtmosPassVertical ) )
 
 //OPEN TURF ATMOS
-#define OPENTURF_DEFAULT_ATMOS		"o2=22;n2=82;TEMP=293.15" //the default air mix that open turfs spawn
+#define OPENTURF_DEFAULT_ATMOS		"o2=21.78;n2=82.36;TEMP=293.15" //the default air mix that open turfs spawn, also is what the station vents output at assuming a 21/79% o2/n2 mix
 #define TCOMMS_ATMOS				"n2=100;TEMP=80" //-193,15degC telecommunications. also used for xenobiology slime killrooms
 #define AIRLESS_ATMOS				"TEMP=2.7" //space
-#define FROZEN_ATMOS				"o2=22;n2=82;TEMP=180" //-93.15degC snow and ice turfs
+#define FROZEN_ATMOS				"o2=21.78;n2=82.36;TEMP=180" //-93.15degC snow and ice turfs
 #define BURNMIX_ATMOS				"o2=2500;plasma=5000;TEMP=370" //used in the holodeck burn test program
 
 //ATMOSPHERICS DEPARTMENT GAS TANK TURFS