Blue streetlights: not UV rays or war weapons

Blue streetlights: visible light, not ultraviolet or war weapons

A neighbor films the new streetlight on their street with a mobile phone. The sidewalk is dyed with a club-like blue, and the video circulates with a message that doesn't talk about lighting: it says these lights "are war weapons." Thus enters one of the most repeated controversies regarding new public lighting in Spain, the replacement of old orange sodium vapor bulbs with bluish LED lights, which some people attribute to ultraviolet emissions. The thesis has circulated for years, relying on home videos and measurements of diffuse origin, and has found no technical confirmation.

What does the message that started the controversy say?

The text opening the issue is a tweet with a photo: an unspecified group is attributed the installation of lights that the message qualifies as weaponry, garnished with the idea that the level of evil has no limits. No data. Just the adjective and the screenshot.

Responses divide quickly. There are those who take it as a joke—whether they serve to distinguish reptilians, whether it's free tanning and people complain anyway—those who ask explanations from the corresponding town hall, and those who light the conspiratorial fuse: if the same tonality appears in all cities at once, they argue, it cannot be coincidence, but a coordinated plan with some hidden purpose. That jump, from aesthetic complaint to global suspicion, marks everything that trinc.

Blue is not ultraviolet: the basic technical error

The confusion has a name. The blue light of LED streetlights is visible light, with wavelengths around 450 nanometers; ultraviolet radiation falls below 400 and is invisible to the human eye. They are two distinct ranges, and confusing them is like calling a scooter a motorcycle because both have wheels. "The blue light of streetlights is not ultraviolet light," concludes a message with just enough patience; they are two different types of lights.

The same happens with the figures being spread. Measurements expressed in V/m, electric field unit, appear, to which an exposure "per hour" is attributed—a formulation that does not correspond to that magnitude—and compared with the 0.2 V/m of thermal noise generated by the human body. The exercise never measures ultraviolet, among other things because streetlights do not emit ultraviolet.

Why were orange streetlights changed for white light?

For two non-conspiratorial reasons: consumption and visibility. With the same level of illumination, white light allows better tonalidad vision, and market studies handled by administrations point out that the public prefers it over the yellowish tone of sodium. The change also came hand in hand with the replacement of lamps from decades ago by current LEDs, a comparison that is almost never done well: old sodium is not measured against sodium, but against technology twenty years newer.

Energy saving as the sole argument does not convince everyone either. "It is not for energy saving, certainly," points out one of the most critical voices regarding the deployment. And there are those who highlight the detail of who pays: town halls and installers adjusting budgets, with the cheapest lamp as the usual criterion.

Sight, sleep and skin cancer: what can be stated

It is convenient to separate two things. That blue light in certain doses and schedules alters the circadian rhythm and can be annoying is something that the discussion itself collects, and light pollution is a recognized problem in cities. It is another thing to make the leap that a streetlight emits ultraviolet and causes skin cancer: that is not supported by what is provided, and the comparison with tanning booths is made without any data backing it up.

Also circulates the idea that vaccinated people react to ultraviolet radiation, with a video as the only proof, and the warning that these lights are designed so that no one sleeps and to keep the population working without rest. Neither of the two statements has any support whatsoever.

From graphene to 6G: how the narrative derives

The issue rarely stays with the streetlights. Before finishing, the conversation has already passed through vaccine graphene, the activation of 5G, an imminent solar storm and a list of stock market drops of a dozen international banks presented as a sign of collapse. A message summarizes the mechanics with irony: anything works as long as it proves that even jam contains surveillance nanobots.

In the end, another ingredient appears. A university research proposes using copper bracelets on forearms to improve data transmission in future 6G networks via visible light communication. It is a laboratory approach, in proposal phase, and cited as such; however, in the narrative, it becomes one more step towards something worse.

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The video that originated the whole chain is from 2010. The movie that inspired the panic's name, from 2009.