wifi off

The airport does have time controls for the wireless.

But unlike modern routers there is no simple off switch. Nor will Apple add one since they stopped production more than a year ago.

Either use the built in time controls to force kids off wifi if that is your concern.

Are you concerned about radiation? Some people are but remember wifi when not making a connection is merely polling .. it is not a continuous signal.

You can make a simple device for your tower model Extreme or Time Capsule. A simple metal cap or tin can placed over the top will cut RF to practically nothing. All the antennas are in the very top of the case.

An old fashioned Tin Can will work a lot better. Steel is much better at blocking EMR.

You can put the TC on a metal plate.. cut slots in the can bottom so it has lots of gaps for ventilation. No radiation should escape because it is now a Faraday cage.

If it is really major issue then buy a new router and relegate the TC to backup duties with the wifi off.

Are you turning off all the other sources of radiation in the house.. because wifi is actually the least of your problems.

Cordless phones, AV or other senders like door bells and baby alarms are far worse. (Ironically in the case of baby alarms).

None of this blocks RF from outside.. or natural radiation of course.

I have a friend who visits occasionally who has become very concerned about EMR

Then, your friend should not ever go outdoors, where he will be constantly bombarded by far more radiation than any wireless router could ever deliver.

Police, fire, emergency radios, etc are always "on" as well as cell phone towers and satellite communications. Don't forget about radio and TV broadcasts as well.

I have a friend who visits occasionally who has become very concerned about EMR

Then, your friend should not ever go outdoors, where he will be constantly bombarded by far more radiation than any wireless router could ever deliver.

Police, fire, emergency radios, etc are always "on" as well as cell phone towers and satellite communications. Don't forget about radio and TV broadcasts as well.

Polling means it announces its presence to any potential client. Then goes silent.. assuming no client is wishing to connect.