Fluorescent lamps with magnetic ballasts flicker at a normally unnoticeable frequency of 100 or 120 Hz and this flickering can cause problems for some individuals with light sensitivity,[4] they are listed as problematic for some individuals with autism, epilepsy,[5] lupus,[6] chronic fatigue syndrome, Lyme disease,[7] and vertigo.[8] Newer fluorescent lights without magnetic ballasts have essentially eliminated flicker.[9] The normally unnoticeable 100–120 Hz flicker from fluorescent tubes powered by electromagnetic ballasts are associated with headaches and eyestrain. Individuals with high flicker fusion threshold are particularly affected by electromagnetic ballasts: their EEG alpha waves are markedly attenuated and they perform office tasks with greater speed and decreased accuracy.[10] Ordinary people have better reading performance using high frequency (20 kHz – 60 kHz) electronic ballasts than electromagnetic ballasts, although the effect was large only for the case of luminance contrast.[11] Early studies suspected a relationship between the flickering of fluorescent lamps with electromagnetic ballasts and repetitive movement in autistic children.[12] However, these studies had interpretive problems[13] and have not been replicated. Compact fluorescent lamps (CFL) are driven by electronic ballasts which operate in the range of 25–60 kHz, which far exceeds the human ability to perceive flicker.
Posted on: Fri, 05 Sep 2014 21:01:26 +0000