An employee states there is insufficinet light to read documents at his desk and suffers headaches as a result. The individual sits next to an external window with plenty of natural light, Lux reading have been taken and are well in excess of the minimum requirement in an office space. An inspection of his desk area shows that there are no light problems. There are approx 24 peopel on each of the 6 floors sit in a simimlar position with no other complaints being made. The employee is still complaining - what else can we do as an employer to address this situation.

Well you cant argue with the evidence... Only in this case you can. Have you supplied the individual with an inexpensive desk lamp yet? Sometimes individuals respond positively to their perception of being listened to. If that doesn't solve it, then I would be considering an OH visit or recommending a trip to his Optician/ GP (based on your evidence and action taken which failed to resolve the problem) in order to check for any underlying medical conditions.