Canadian Occupational Safety

DECEMBER/JANUARY 2018 23 on to reduce the backlight. Like the app, it automati- cally adjusts light and colour at sunrise and sunset. "These are two practical things one can do that are fairly easy," Gordon says. Workers can adjust the level of blue light emitted from their screens by simply decreasing the bright- ness of the screen or by altering the contrast by switching to white-on-black. Safety managers can limit the amount of blue light produced by overhead lighting, Gordon says. Avoid cool white or blue-white fluorescent tubes and instead install ones that are coated, so they produce less blue light and emit a warm white light. Also, replace flickering fluorescent tubes quickly because faulty tubes emit more blue light. Gordon says it may also be a good idea to stay away from white desks. The effect of the white sur- face is similar to that created for skiers by a bright sun on snow. "White desks reflect anything coming out of the computer, so you're getting a double whammy. If you're sitting at a white desk and you have a fluores- cent light, then it is going to reflect off the desk into your eyes. I would recommend people have dark- coloured desks," he says. BLUE-BLOCKING GLASSES Glasses that block blue light work by filtering out the shorter wavelengths of visual light that would otherwise activate light receptors in the eye and send a signal to the region of the brain that controls the production of melatonin. These glasses, which have orange-coloured lenses, also come in a "fit-over" size, designed to be worn over prescription glasses. "What you want to do is cut out the blue light in the two to three hours before you go to bed," Rao says. "A handful of studies have shown your body actually responds to cutting out blue light in the same way it would if it were nighttime." One advantage of the eyewear is that people don't have to try to give up looking at electronic screens at night, Rao says. The glasses affect colour perception, however, so some kinds of work cannot be done while wearing them. Workers on night shifts who are concerned about their exposure to blue light should con- sult their safety manager before getting a pair of glasses that block blue light, Rao says. Blue- blocking glasses reduce alertness so this may not be appropriate at work. Experts are div- ided, he adds, about whether workers should wear the glasses at night: Some believe night- shift workers need a lot of light to stay alert, while others say disruption to the circadian rhythm should be minimized as much as pos- sible and blue-blocking glasses would help achieve that. "Shift work is trickier. It requires more careful consideration," Rao says. "I wouldn't recommend that (everyone) who works a night shift should wear the glasses. It has to be decided on a case-by-case basis." The CSA currently has no standard regarding blue light in its occupational health and safety pro- gram. However, there are international standards, Gordon says. One study that tested light-emitting devices found the devices tend to emit levels of blue light well below the safety limits set by the international standards. "The study looked at all types of light bulbs, com- puter screens and laptops and they were all in the range of 10 to 20 per cent of the exposure limit of the standard," he says. "Manufacturers of these devices have to make sure the amount of blue light they emit is significantly less than the standard that is set." As the City of Ottawa prepared to roll out its new LED street lamps, Dick told CBC that city managers could reduce some of the adverse affects of the blue light simply by dimming the lights. But it's a practice most big cities do not follow. "Life has evolved on Earth for four billion years with the light and dark contrast. It's literally in our DNA," he said. "And once you disrupt that light, once you add light in the nighttime — that throws off our biochemistry. There are no winners in that." Linda Johnson is a freelance journalist based in Toronto. She can be reached at lindajohnson@ sympatico.ca. 5 ways to decrease exposure to blue light eye. The short wavelengths penetrate to the back of the eye, harming the retina cells. Long-term, that damage can lead to macular degeneration, a condi- tion in which a person loses his or her central vision (peripheral vision is unaffected) and can no longer see fine details. People looking at computer screens all day are most potentially at risk for eye damage, says Keith Gordon, vice-president of research at the Toronto-based CNIB. "Typically, there's not a lot of concern because of the light itself, but people spend hours looking at these screens, so there is a concern that if you spend your day looking at a computer monitor, with that amount of light, you could have long-term damage in the eye," he says. It is important to note, however, that the direct connection between long-term exposure to blue light and retinal damage in humans has not been abso- lutely proven, Gordon stresses. "I don't think it has ever been definitively said that long-term exposure to blue light can in fact damage the retina. But there's an association, and there are animal studies that show that blue light can be toxic to retina cells," he says. In addition to retina damage, prolonged exposure to blue light can lead to earlier cataract formation and, most commonly, to eye strain, North says. Hours of looking at a computer screen can produce slightly blurred vision. Many studies have shown that computer eye strain can decrease productivity by 20 per cent, she adds. Eye strain can become a chronic problem if it is not addressed. PROTECTING WORKERS Safety mangers can reduce worker exposure to blue light by putting screens that block out some blue light over the computer monitors, North says. Work- ers should also be allowed to take regular breaks to give their eyes a rest from the blue light. It's also a good idea, she adds, to have workers see an optome- trist regularly, have an eye exam and wear the correct glasses for proper vision. In addition, it is possible to use software to reduce blue-light exposure, Gordon says. Filter apps, such as the f.lux, which is free, can be installed in comput- ers and mobile devices to adjust light emitted to the time of day: very bright during the day and subdued at night. Moreover, many devices now come with a blue-light reduction mode, a setting the user turns SCREEN TIME: Try to decrease the amount of time spent in front of screens and take frequent breaks to give the eyes a rest. FILTERS: Screen filters are available for smartphones, tablets and computer screens. They decrease the amount of blue light given off from these devices that could reach the retina in the eyes. COMPUTER GLASSES: Computer glasses with yellow-tinted lenses that block blue light can help ease computer digital eye strain by increasing contrast. ANTI-REFLECTIVE LENSES: Anti-reflective lenses reduce glare and increase contrast; they also block blue light from the sun and digital devices. INTRAOCULAR LENS (IOL): After cataract surgery, the cloudy lens will be replaced with an intraocular lens (IOL). The lens naturally protects the eye from almost all ultraviolet light and some blue light. There are types of IOL that can protect the eye and retina from blue light. Source: Prevent Blindness LOOKING FOR A SUPPLIER OR VENDOR? Visit hrreporter.com/hr-vendors-guide

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