UPDATE:
I personally went out and visited the cameras today. I noticed a oily mist all over the inside and outside of the lens. After cleaning all of them, the picture is perfect! It appears that coolant from some of the milling machines must have worked its way in there. Apparently these have been running for about 3 years up until now.
It is interesting that the security camera vendor came out for a fee ($90) and concluded that the problem was with the AGC and the iris's in all of the cameras. We were then quoted $1800 to replace all of the cameras.