Before switching to energy-efficient, blue light-emitting LED streetlights, officials at the city of Montreal questioned the impact of the lights on citizens’ sleep, reports

To address those concerns, the city of Montreal asked the Quebec public health department to look into the matter and consider the colour spectrum used by the lights.

The department considered the research but ended up green-lighting the project, saying that the switchover likely wouldn’t lead to a significant increase of exposure to blue light.

The costs of switching over to LED streetlights are estimated at $110 million, but Montreal anticipates long-term savings of nearly $300 million over 20 years.

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