If the player enters the smoke it won't kill them only if the smoke spawns. What is needed?

-- Configs
local tool = script.Parent
local player = game.Players.LocalPlayer
mouse = player:GetMouse()
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tool.Equipped:connect(function()
	mouse.Button1Down:connect(function()
		local ray = Ray.new(tool.Handle.CFrame.p, (mouse.Hit.p - tool.Handle.CFrame.p).unit * 300)
		local part, position = workspace:FindPartOnRay(ray, player.Character, false, true)
		local gas = Instance.new("Part",workspace)
		gas.Transparency = 0.4
		gas.Anchored = true
		gas.CanCollide = false
		gas.Shape = "Ball"
		gas.Size = Vector3.new(.4,.4,.4)
		gas.BottomSurface = 0
		gas.TopSurface = 0
		local Smokey = Instance.new("Smoke",gas)
		Smokey.Size = 10
		local distance = (tool.Handle.CFrame.p - position).magnitude
		gas.Size = Vector3.new(0.3, 0.3, distance)
		gas.CFrame = CFrame.new(tool.Handle.CFrame.p, position) * CFrame.new(0, 0, -distance / 2)
		game:GetService("Debris"):AddItem(gas, 5)
		distance = (gas.Position - player.Character.Humanoid.Torso.Position).magnitude
		while true do
		if distance < 10 then
			game.Players.LocalPlayer.Character.Humanoid.Health = 0
			wait (1)
			end
		end
	end)
end)