The Federal Emergency Management Agency sent out an electronic warning tone to every TV, radio and cellphone in the U.S. on Wednesday Oct, 4. The Nationwide Emergency Alert Test was part of a routine procedure to ensure the alert system is still an effective way to warn Americans about emergencies.

The national practice alert was the first sent out since 2018.

The alert test went out two minutes earlier than expected and lasted approximately one minute.

The Federal Emergency Management Agency uses alerts to warn Americans about emergencies, natural catastrophes, attacks and accidents at the national level.

But the test is also causing some online conspiracy theories. Here's what you need to know:

When is the big emergency alert test?:Expect your phone to ominously blare today.

What do conspiracy theories claim?

QAnon influencers are taking to the internet to spread misinformation about the emergency alert. Some claim the alert will “activate” deadly diseases within vaccinated people—warning followers to turn off their phones. Such claims have been seen by thousands of people on X, formerly known as Twitter.

According to the Associated Press, conspiracy theorists are also spreading debunked information that the emergency broadcast system test is sending signals to phones that activate nanoparticles such as graphene oxide that have been introduced into people’s bodies.

Emergency alert controversy:No risk FEMA alert will activate body's chemicals | Fact check

Conspiracy theories debunked

Jeremy Edwards, press secretary and deputy director of public affairs at FEMA said there are no known harmful health effects from the signal. The claims bring back long-debunked conspiracy theories about the contents of the COVID-19 vaccine. The alert signal is a routine practice from FEMA and the signal used is the same familiar tone that has been used since the 1960's.

Another online conspiracy claimed that the alert could somehow activate viruses in people who have been vaccinated, turning them into zombies.

"I received it on my phone and saw it on the TV. And I can confirm to you that I am not a zombie," said Edwards.

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What is the emergency alert used for?

FEMA has used the emergency alert about 84,000 times to share important information with the public about topics ranging from weather events to missing children and other emergencies.

To read more about the debunked conspiracy, see USA TODAY's fact check reporting.