@Mod(...)
public class mod{
	@EventHandler
	public void load(FMLIntitializationEvent event){
		MinecraftForge.event_bus.register(new OxygenAtmosphere);
	}
}
import micdoodle8.mods.galacticraft.api.event.oxygen.GCCoreOxygenSuffocationEvent.Pre;
public class OxygenAtmosphere{
	@ForgeSubscribe
	public void cancelDamage(Pre event){
		if(provider.getDimensionID == OxygenAtmospherePlanetID)
			event.setCancelled(true);
	}
}