Gold Standard

You may have spotted this publication last week from some of my heroes - New comprehensive report on Health Effects of Solid State Lighting. A timely update of the seminal 2014 ANSES review -?OPINION of the French Agency for Food, Environmental and Occupational Health & Safety, now integrating new understanding of biology and medicine.?

It’s a long read but well worth the effort if you design, build or maintain places to work, live or learn - that’s probably almost everyone if you count regular folks who buy lights for their home-office or child’s new room at college.?

Here are some of my key takeaways - would love to hear your thoughts.?

1. Biology is blind?

Your body and brain don’t care where the light comes from - natural or artificial. So all light can be healthful or harmful. But Solid State Lighting (including LEDs) offers immense potential - and poses specific risks - to human health because of the way they generate light.?

2. Blue light hazard?

While skin exposure is not a risk for most, bright and prolonged light exposure can damage the retina. Wavelengths below 430nm pose a greater risk because they’re higher energy and travel further into the eye. Current standards (e.g. IEC 62471-7) may be too permissive to protect vulnerable populations, allowing up to 10 times greater exposure than the new harmonised IEC regulations. The report suggests manufacturers should be required to provide more data on the spectral emissions below 430nm on their products. This is particularly relevant for the blue- or violet—enriched sources developed for spectral tuning and circadian effects. Noting that sensitivity is higher at night, the team recommend that luminaires with a lower risk group should be used in spaces used after dark until more evidence is available.?

3. Glare - the most common cause of complaints?

Although any light source can cause glare, LED poses a particular problem as it delivers intense brightness in a small package. Distribution is one factor, but the report notes that spectrum plays a critical role too: ‘cooler’ sources may be more likely to trigger discomfort than warmer ones. Interestingly, you’re less sensitive to glare later in the day - although the reasons aren’t yet clear. More research would help to deliver the light levels we need without the headache.

4. Flicker, or Temporal Light Modulation - a pain in the neck?

The rapid fluctuations in brightness caused by the conversion of power into light can interfere with our ability to see clearly and accurately, causing flicker, strobing and phantom array effects. It can also interfere with your brain’s ability to process the information, reducing speed and accuracy, increasing fatigue, causing headaches and even epilepsy in some populations. The team suggest that manufacturers should be required to test their products over the full range of dimming to help buyers make informed decisions, even where not required by law.?

5. Circadian effects?

'Given that it is well established that a healthy pattern of light and dark every day is necessary for good health, all lighting recommendations should reflect the need to deliver this pattern.

While this basic principle of bright days and dark nights is understood with a baseline recommendation of 250 melanopic EDI during the day, less than 10 in the evening and less than one during sleep, crucial factors such as the dose-response have still to be clarified. Interestingly, the report does reference evidence of the role of spectra outside the visible range such as infra-red and uItraviolet in circadian entrainment, noting that for day-active people, daylight is the only source currently capable of delivering the brightness and spectrum that we need - electric lighting cannot match it.??

‘Unfortunately, some populations cannot access daylight. In their cases, measures should be taken to make their daily light exposure higher and their nights darker. Nursing homes, long- term care facilities, and prisons should implement such measures to help maintain the individual and collective quality of life in their premises. Authorities could consider adapting their service requirements for these institutions to mandate appropriate light exposures for residents’?

6. Acute effects

The team notes that exposure to bright, cool wavelengths seems to increase subjective alertness and that these effects are greater in the evening and night than during the day. Melanopic lux is a more accurate measure of these effects than photopic lux (i.e. weighted towards the ‘blue’) but the team urges caution when it comes to making a direct link between a single photoreceptor and mood or attention as the results are inconsistent suggesting that other factors may be in play.?

7. Long-term effects?

There is a clear link between a lack of daylight exposure and the current epidemic of myopia - screens are only a problem because they have displaced time outside. Other links such as AMD (Age-related Macular Degeneration) and cancer are less clear.?

Here again the report references promising evidence of the potential benefits of short wavelength and infra-red light in these conditions, but urges caution, noting that introducing these wavelengths without detailed understanding of the mechanisms involved could have unintended consequences.?

In summary?

Light triggers powerful short and longer-term physiological effects especially in vulnerable people who have reduced daylight.?

There is a tension between the need to reduce energy use and our need for increased light levels during the day to support mental and physical health.?

It is time for the environmental, health and lighting sectors to join forces to create a brighter future for us all.