Street light flicker is new hazard, says watchdog

FLICKER FROM LED street lights could be becoming a health hazard, the UK government’s official health watchdog for England has warned.

Public Health England says in its annual medical report, published this month, that the phenomenon is ‘of concern’.
Some of the LED sources assessed by Public Health England and others vary in illuminance at a frequency of 100 hertz. At the extreme, the LEDs switch on and off 100 times per second. ‘This is of concern for a number of reasons,’ writes John O’Hagan, group leader at PHE and a visiting professor in laser and optical radiation safety at Loughborough University.
‘Some people seem to be very sensitive to this light modulation, resulting in headaches, migraine and less specific feelings of malaise. However, most people will experience phantom arrays.

‘[This] happens when you move your eyes quickly when behind a car with its brake lights on, particularly in the dark, and there is the risk of a stroboscopic effect. This effect may manifest itself as moving objects appearing to jump, rather than move smoothly.
‘More seriously, rotating machinery, which could include the blades on a food mixer, may appear to be stationary if the rotation rate matches the modulation rate or is a multiple of it.’
O’Hagen says glare and blue light are also concerns with LEDs. ‘Some LED installations, however, have LED chips visible, which can form a source of glare.

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