Oxygen script works, but not at the right time. Help me fix it? [STILL UNSOLVED]

Anyways, this is my script. I'm making a DOOM game, and if you go outside of the building, you start suffocate, in other words, you have limited Oxygen. But, the only thing is, it WORKS, but....it works when it's not supposed to. In other words, your oxygen level drops even when you're inside. I was wondering if someone could fix this. (Problem starts on line 82.) Also, this is a heavily modified under water script.

Here is the video to what I am trying to recreate (in terms of the Oxygen GUI.) https://www.youtube.com/watch?v=ZFeSDs5hUG4#t=530

local player = script.Parent.Parent.Parent.Parent
repeat wait() until player.Character

local lastHealth = 100
local lastHealth2 = 100
local maxWidth = 0.96

local humanoid = script.Air

function UpdateGUI(health)
	tray = script.Parent
	local width = (health / humanoid.MaxValue) * maxWidth
	local height = 0.83
	local lastX = tray.bar.Position.X.Scale
	local x = 0.019 + (maxWidth - width)
	local y = 0.1
	
	tray.bar.Position = UDim2.new(x,0,y, 0) 
	tray.bar.Size = UDim2.new(width, 0, height, 0)
	-- If more than 1/4 health, bar = green.  Else, bar = red.
	if( (health / humanoid.MaxValue) > 0.25 ) then
		tray.barRed.Size = UDim2.new(0, 0, 0, 0)
	else
		tray.barRed.Position = tray.bar.Position
		tray.barRed.Size = tray.bar.Size
		tray.bar.Size = UDim2.new(0, 0, 0, 0)
	end
	
	if ( (lastHealth - health) > (humanoid.MaxValue / 10) ) then
		lastHealth = health

		if humanoid.Value ~= humanoid.MaxValue then
			delay(0,function()
				AnimateBars(x, y, lastX, height)
			end)
		end
	else
		lastHealth = health
	end
end


function HealthChanged()
	health = humanoid.Value
	UpdateGUI(health)
	if ( (lastHealth2 - health) > (humanoid.MaxValue / 10) ) then
		lastHealth2 = health
	else
		lastHealth2 = health
	end
end

function AnimateBars(x, y, lastX, height)
	tray = script.Parent
	local width = math.abs(x - lastX)
	if( x > lastX ) then
		x = lastX
	end
	tray.bar2.Position = UDim2.new(x,0, y, 0)
	tray.bar2.Size = UDim2.new(width, 0, height, 0)
	tray.bar2.BackgroundTransparency = 0
	local GBchannels = 1
	local j = 0.2

	local i_total = 30
	for i=1,i_total do
		-- Increment Values
		if (GBchannels < 0.2) then
			j = -j
		end
		GBchannels = GBchannels + j
		if (i > (i_total - 10)) then
			tray.bar2.BackgroundTransparency = tray.bar2.BackgroundTransparency + 0.1
		end
		tray.bar2.BackgroundColor3 = Color3.new(1, GBchannels, GBchannels)
		wait(0.02)
	end
end

humanoid.Changed:connect(HealthChanged)

while wait() do
	function findHighestBrickInPlayer(char)
	local brick = nil
	function check(part)
		if part.className == "Part" or part.className == "WedgePart" then
			if brick == nil or part.CFrame.y > brick.CFrame.y then
				brick = part
			end
		elseif part.className == "Hat" or part.className == "Model" then
			for i,child in pairs(part:getChildren()) do
				check(child)
			end
		end
	end
	check(char)
	return brick
end

function isExposed(brick)
	local testray = Ray.new(brick.Position, Vector3.new(0,999,0))
	local part, pos = workspace:findPartOnRay(testray, brick)
	if part == nil then
		return true
	end
	return false
end
	if player.Character.Humanoid.Health ~= 0 then
		if isExposed then
			if humanoid.Value > humanoid.MinValue then
				script.Parent.Visible = true
				humanoid.Value = humanoid.Value-0.1
			elseif humanoid.Value <= humanoid.MinValue then
				player.Character.Humanoid:TakeDamage(100)
			end
		else
			if humanoid.Value < humanoid.MaxValue then
				humanoid.Value = humanoid.Value+5
			else
				script.Parent.Visible = false
			end
		end
	end
end