FEMA, FCC planning nationwide test of emergency alert system. Why you don't need to be alarmed.

Don’t be alarmed when your cellphone starts blaring and vibrating Wednesday afternoon.

The Federal Emergency Management Agency and the Federal Communications Commission will conduct a nationwide test of the Emergency Alert System and Wireless Emergency Alerts that will result in most U.S. mobile phone users receiving a notification on their electronic devices, federal officials announced.

This will be the second time the test includes all cellular devices, according to a news release, but it will be using the same familiar audio tone that’s been in use since the 1960s to broadcast warnings across the country, according to a spokesperson for FEMA.

Still, that hasn’t stopped misinformation — and disinformation — from spreading around the internet, particularly social media.

Before you get caught up in those claims, here’s what you can expect.

When will this test happen?

According to FEMA and the FCC, Wednesday at about 2:20 p.m.

How will the test work?

Officials said it will take place in two portions: The WEA [Wireless Emergency Alerts] will be directed to all consumer cellphones. The EAS [Emergency Alert System] portion will be directed to radios and televisions.

What languages will the test be conducted in?

English will be the base language. However, if your devices are set to Spanish as your language preference, the messages will be in Spanish.

In English, messages will read: “THIS IS A TEST of the National Wireless Emergency Alert System. No action is needed.”

In Spanish, those messages will read: “ESTA ES UNA PRUEBA del Sistema Nacional de Alerta de Emergencia. No se necesita acción.”

What’s the purpose of this test?

FEMA and the FCC said the purpose of the test is “to ensure that the systems continue to be effective means of warning the public about emergencies, particularly those on the national level.”

Richard Rotanz, a former emergency management official in Nassau County and New York City, said it’s crucial to test an emergency alert system — before disaster strikes — and it’s a best practice.

“It’s like a fire drill, practicing CPR. It’s a good thing,” he said.

How long will the test last?

The WEA tests will be broadcast for 30 minutes. Officials said the messages should be received just once, but there’s always that accompanying blaring alarm and “unique vibration” to get your attention.

The EAS portion of the test is scheduled to last approximately one minute.

There are rumors flying around the internet saying I should avoid work Wednesday — or keep my kids home from school. Should I be concerned?

No. Treat it like any other normal work or school day, officials said. If it were a real emergency — if there was an imminent weather threat, an Amber Alert or a presidential or other government alert — you’d get a message defining an actual emergency. This is merely a test. Not a real emergency. Officials said don’t treat it like one.

What if a real national emergency breaks out on Wednesday?

If the Wednesday test has to be canceled because of “widespread severe weather or other significant events,” it will be rescheduled to Oct. 11, according to FEMA.

With Matthew Chayes and AP

By John Valenti

john.valenti@newsday.com

John Valenti, a reporter at Newsday since 1981, has been honored nationally by the Associated Press and Society of the Silurians for investigative, enterprise and breaking news reporting, as well as column writing, and is the author of “Swee'pea,” a book about former New York playground basketball star Lloyd Daniels. Valenti is featured in the Emmy Award-winning ESPN 30-for-30 film “Big Shot.”