I am 99.9999% sure this is airport specific and related to energy efficiency. It is no different than what 1000s of businesses, cities and even individual homeowners are doing. My company replaced all of the office fluorescent lighting about a year or so ago. The fixtures remained (standard 2x4 drop ceiling), but they changed out the ballasts and bulbs. Between the electricity savings and government rebate programs, the payback period was something like one year. It is a whiter light, but still not my favorite for work environment.