Don’t use white desks with office lights, says eye charity

WHITE-COLLAR workers shouldn’t sit at white desks while under modern office lighting, a top official from a leading eye charity has warned.

Keith Gordon, vice-president of research at the Toronto-based Canadian National Institute of the Blind, says it would be a prudent to stay away from white desks to reduce any hazard from over-exposure to blue light.

The effect of the white surface 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 fluorescent light, then it is going to reflect off the desk into your eyes. I would recommend people have dark-coloured desks,’ he told Canadian Occupational Safety magazine.

The direct connection between long-term exposure to blue light and retinal damage in humans has not been absolutely proven, Gordon stresses. Picture: Alex Ageev

‘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 absolutely 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.

Gordon recommends the office workers use software to cut blue-light exposure, such as filter apps such as the f.lux, which is free, can be installed in computers and mobile devices to adjust light emitted to the time of day: bright during the day and low at night. Additionally, many computers and smart phones now have a blue-light reduction mode. Like the app, it automatically 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 brightness 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. He urges facility managers to avoid installing cool white or blue-white fluorescent tubes and instead specify ones that are coated, so they produce less blue light and emit a warm white light. He also recommends replacing flickering fluorescent tubes quickly because faulty tubes emit more blue light.

 

  • Blue light exposure will be one of the topics explored in the Workplace and Wellbeing Conference taking place at LuxLive 2018 on Thursday 15 November at London ExCeL. Entry is free if you pre-register HERE.

 

 

Pic: Shutterstock

Comments 5

All of the science cited in other comments is one thing (and highly valid)... but I’m more concerned that the article is about “modern office lighting” and only mentions fluorescent! Seriously? Quite clearly they don’t get the Daily Mail in Canada otherwise this would be another anti-LED rant about cancer as well, or maybe they do get it and are deliberately not talking about LEDs? Either way, in all seriousness, the white desk is not the biggest problem, a poorly designed lighting scheme is the problem. The white desk may well be an obvious symptom, but it’s not the cause. Stating it has a similar effect to snow reflection is perhaps overstating the case somewhat to create a better soundbite. I’m not aware of many offices being lit to >15,000 Lux as you could expect from daylight, so I dispute the effect is even remotely similar to sunlight reflected off snow (where you also often have the additional problem of more UV due to higher altitude). Further, the seemingly blanket suggestions in the media at the moment (repeated here) that using a night shift type filter on mobile phones, tablets, etc. will help matters is completely ignoring the fact that some visual tasks on these devices require a balanced colour spectrum rather than a biased one and also ignores the reduction in contrast and/or brightness which can have knock-on effects by way of eye strain. It's the useless one-size-fits-all approach that, even today, means it is still possible to buy CAT2 grid luminaires. Apparently what is (or was) good for the majority is good for the minority too. The only good thing that can come out of announcements like this, delivering tiny facts as though they are total facts, is that it starts the conversation.

Reflected light from the work surface is perhaps the least worrisome (and least effective) in terms of circadian impact. It is now known that there are at least 3 types of melanopsin expressing retinal ganglion cells in the human retina, and predominantly it is the M1 ipRGCs which signal the SCN for circadian entrainment. Moreover, the highest density of these ipRGCs occur in the lower front region of the retina where they are optimally positioned to receive irradiance from the sky. Accordingly, they are most sensitive to overhead lighting while reflected light entering the eye from below has a much lesser impact. The primary lighting criteria for selecting a work surface finish relates to managing workstation luminance ratios not circadian impact. A matte white or light colored work surface may be appropriate where horizontal visual tasks include white paper documents. To maintain a 3:1 luminance ratio between a white paper task having a reflectance factor of 0.90 and the surrounding work surface, the work surface must have a reflectance factor of 0.30 or greater. Surfaces with a reflectance factor greater than 0.30 will reduce the contrast further and minimize visual fatigue. The same goes for the contrast between visual displays and the work surface. In general, work surfaces with dark and specular finishes should be avoided. Any concern or preference for the spectral content of light should be addressed at the source while intensity should be addressed via dimming.

This article raises some good points. Quote: "‘I don’t think it has ever been definitively said that long-term exposure to blue light can in fact damage the retina." We need to bear in mind that there is an IEC safety standard (62471) concerning photobiological safety of light sources and which includes a blue light hazard (BLH) action spectrum to help define an exposure limit value (ELV) to blue light. As far as I am aware, it is unlikely that desk lighting to say 500 lux at the desk would exceed the daily BLH ELV in this standard (c.f. so-called 500 lux criterion for white light), but what happens for daily exposures over the long term is not really clear. We need more data or re-evaluation of existing data. For example, there is a degree of analytical data for SAD type light boxes - these usually irradiate the face/eye at around 10000 lux for around 30 minutes each day and this will include a photobiologically 'active' proportion of blue light: so that is a very good place to start looking. Accordingly I believe the clinical data for SAD treatments should be re-visited ASAP to place everything in context, likely only ICNIRP (world-wide) and Public Health England (PHE UK) can initiate such a study, until then the jury is somewhat out. Alan Tulla's comments on glare from a white surface are very well noted here too.

There are many more things than blue light to consider when designing good quality lighting schemes - including what you replace white or light-coloured desks with. High contrast is a key factor in eye-tiredness and you might just replace one (alleged) problem with another. White/light surfaces can provide good reflectance and help to reduce the flux required in a space to achieve the required illuminance, as well as reducing contrast between white paper and the surface. CAD operators use both paper and screens. Also, are we now saying that blue carpets etc must be avoided to avoid 'blue' light being reflected around a space? There are also other, better, reasons than blue light to replace flickering lamps...

Forget the blue light, a bright white desk will increase glare and visual discomfort especially if the luminaire is directly overhead. Reducing the luminance of the screen will make the situation worse. Luckily, today's screens where lettering is black on a white background ameliorates the situation but I feel sorry the CAD engineers with black screens and bright white desks.

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