Dock Door Fall Protection

I have dock doors that are left open for air flow. Currently there is a top chain and a mid chain. I believe they are at the proper heights and strength requirements.

They just look.. not right. I couldn't find a standard or LoI covering the use of chain for dock door fsll protection.

Does anyone have insight on this topic? If chains can be used, great. If not, the scope to upgrade the fall protection will greatly increase.