City denies colour temperature switch is due to protests

SEATTLE has become one of the first major cities to announce a switch to warmer colour temperatures for its street lights.

The municipality says it will replace its original 4000K LED luminaires with warmer 3000K following protests from residents.

However, the public utility responsible for the street lighting network, Seattle City Light, denies that the switch is in response to residents’ concerns or the widely-publicised warning by the American Medical Association in 2016 concerning the impact of high-intensity LED street lights on human health and wildlife. The AMA recommended that colour temperatures should not exceed 3000K.

The colour temperature of street lights has become a major issue, partly for the perception that cooler colour temperatures such as 4000K and even 5000K deliver more harmful blue light. Pic: Dominic Alves via FlickrMedia Commons 2017

The colour temperature of street lights has become a major issue across the world, partly for its glare and partly for the perception that cooler colour temperatures such as 4000K and even 5000K deliver more blue light, which has become associated with poor sleep and even higher rates of cancer.

Scott Thomsen of Seattle City Light said that while he is sceptical of the AMA’s conclusions, he wouldn’t deny that blue light can be bad for sleep. However, Thomsen believes the blue light from televisions and devices such as smart phones is far more of a concern than that produced by street lights.

Thomsen also said that the American Medical Association’s recommendations played no direct role in the decision to change the specification of the city’s luminaires.

Earlier this year a study by the Barcelona Institute for Global Health and the University of Exeter linked blue light from LED street lights to a ‘significant increase' in the risk of breast and prostate cancer.

It found that participants living in large cities with heavy exposure to blue lights at night had double the risk of prostate cancer and 1.5 times higher risk of breast cancer. This was compared to populations with less exposure to blue light.

The researchers found the bluer the light emission that people in large cities were exposed to, the higher the risk of cancer. The study also found that people who lived in homes with darker rooms, by using window shutters for example, had lower risk than those who did not.

The study included medical and epidemiological data of more than 4,000 people between 20 and 85 years of age in 11 Spanish regions. It particularly examined Madrid and Barcelona.

 

  • Urban lighting is the subject of the new Safer Cities Conference which takes place on Wednesday 13 November and Thursday 14 November 2018 at the LuxLive exhibition at London ExCeL. For more information on the event, click HERE.