A bizarre conspiracy linking 5G and coronavirus has taken hold in the UK and being peddled by conspiracy theorists and celebrities on social media.

The theory runs roughly like this: the rollout of faster 5G internet is either causing or acclerating the spread of the coronavirus. It’s hard to pinpoint the source of the theory, and BI first heard a variant of the rumour in early March, but it appears to have picked up steam during the first week of April.

The conspiracy theory and its various offshoots are baseless but have led to real-world harm, with several arson attacks thought to have been perpetrated on 5G masts around the country.

Here’s everything we know about how the conspiracy theory began to circulate:

According to UK fact-checking website Full Fact, a version of the theory appeared on Facebook by late January.

Full Fact’s first debunking of the theory hinged on a Facebook post which claimed Wuhan in China – where the coronavirus outbreak first began – is also where 5G began to roll out.

The post rested on the pre-existing conspiracy theory that 5G suppresses people’s immune systems. It was posted to an anti-5G Facebook group, and was subsequently marked by Facebook as misinformation. According to Facebook, the post had just over 300 shares.

There is no evidence to suggest that Wuhan was the very first Chinese city to start building out 5G, but rather multiple reports found by Full Fact said it was among multiple cities selected to pilot the technology.

There is no evidence that 5G — or any other kind of radio waves — are harmful to people.

Radiowaves are found at the low end of the electromagnetic spectrum, and as such produce non-ionizing radiation, meaning they do not damage the DNA in cell tissue.

International radiation watchdog the International Commission on Non‐Ionizing Radiation Protection (ICNIRP) set new guidelines for 5G frequency last month and confirmed that the frequencies at which 5G will be deployed will be safe.

“The guidelines have been developed after a thorough review of all relevant scientific literature, scientific workshops and an extensive public consultation process. They provide protection against all scientifically substantiated adverse health effects due to [electromagnetic field] exposure in the 100 kHz to 300 GHz range,” ICNIRP chair Dr Eric van Rongen told the Guardian.

On March 13, Full Fact identified and debunked another more widely-shared Facebook post which pinned the blame on Bill Gates.

According to Full Fact, this post claimed that coronavirus is a fiction invented to cover up the physical damage being done by 5G.

It also claimed that the coronavirus was invented by Microsoft billionaire Bill Gates to control the world by creating a vaccine for it.

Gates has said he is funding vaccine candidates.

The post has now been removed from Facebook, but according to Full Fact, it was shared thousands of times.

Coronavirus has spread rapidly in countries with no 5G.

As Full Fact points out in a more recent dismantling of the conspiracy theory, the coronavirus outbreak has had a profound impact on countries with no 5G coverage, such as Iran.

The theory had crystallised enough by March 26 that a British tabloid ran an article on it.

The article was originally headlined “Coronavirus: Fears 5G wifi networks could be acting as ‘accelerator’ for disease,” but was subsequently changed to “Coronavirus: Activists in bizarre claim 5G could be acting as ‘accelerator’ for disease.”

Some celebrities began to amplify the theory.

Actor Woody Harrelson shared a chunk of text on Instagram which suggested 5G could be “exacerbating” the pandemic.

The text is an excerpt from an article by Martin Pall, a retired professor from Washington State University, who has also pushed a theory that Wi-Fi is harmful to human health.

“Alot of my friends have been talking about the negative effects of 5G,” Harrelson wrote in the caption.

“Though I haven’t fully vetted it I find it very interesting,” he added.

The post had more than 25,000 likes at the time of writing.

In early April, arsonists started attacking phone masts in the UK.

Phone masts in Birmingham, Liverpool, and Belfast were damaged in arson attacks in early April. Not all the masts are necessarily 5G towers.

While it’s not yet certain what motivated these specific attacks, the mayor of Liverpool said he had received threats after condemning the 5G/coronavirus theory, and the Irish News reported that in footage of the mast being set on fire voices could be heard saying “f**k 5G.”

Mobile telecoms expert Peter Clarke discovered a Facebook group urging people to burn 5G towers, and reported it.

The Verge reports that while Facebook was slow to act, the page has now been removed.

A video circulated on Twitter showing a woman accosting engineers laying cables.

The video was taken by a woman who approaches two engineers laying fibre-optic 5G cables, falsely claiming that they are not key workers and that 5G “kills people.” Telecoms engineers have been designated key workers by the UK government.

Britain’s big telecoms companies released an open letter appealing to people not to damage the masts or abuse their engineers.

EE, O2, Three, and Vodafone released the statement together.

“Not only are these claims baseless, they are harmful for the people and businesses that rely on the continuity of our services,” the companies wrote.

They said that in some cases abuse of engineers had hindered “essential network maintenance” from taking place.

Vodafone UK CEO Nick Jeffery added in a LinkedIn post that both police and counter-terrorism authorities are investigating the attacks.

The UK government addressed the spread of the conspiracy theory on April 5.

Cabinet Minister Michael Gove called the theory “dangerous nonsense,” and the national medical director of NHS England Stephen Powis condemned it in even stronger terms.

“The 5G story is complete and utter rubbish, it’s nonsense, it’s the worst kind of fake news,” said Powis.

“The reality is that the mobile phone networks are absolutely critical to all of us, particularly in a time when we are asking people to stay at home and not see relatives and friends. But in particular those are also the phone networks that are used by our emergency services and our health workers,” he added.

“I’m absolutely outraged, absolutely disgusted that people would be taking action against the very infrastructure that we need to respond to this health emergency,” said Powis.

UK lawmakers suggested the rumours could potentially be boosted by deliberate disinformation campaigns.

“We’ve called on the government to work with social media companies to stamp out deliberate attempts to spread fear about COVID-19 and it is right that they are being called to account for allowing disinformation on their platforms,” said Julian Knight, chair of the DCMS parliamentary committee.

“We’re also calling on Ofcom [the UK’s media watchdog] to investigate whether international news organisations are using social media to disseminate state-backed disinformation on COVID-19 in order to get around UK broadcasting regulation,” he added.

Big tech is taking some action to crackdown on the conspiracy theories.

A Facebook spokesperson told The Telegraph that posts claiming a link between coronavirus and 5G would be subject to third-party fact-checks, but said conspiracy theories are not banned on the platform.

Meanwhile YouTube said it will remove videos which link 5G and the coronavirus.

“We have clear policies that prohibit videos promoting medically unsubstantiated methods to prevent the coronavirus in place of seeking medical treatment, and we quickly remove videos violating these policies when flagged to us,” a YouTube spokeswoman told Business Insider.

She added that “borderline” videos about 5G which don’t mention coronavirus may be allowed to remain on the site.

This article first appeared on Business Insider Australia, Australia’s most popular business news website. Read the original article. Follow Business Insider on Facebook or Twitter.