Older pacemakers could be adversely impacted if people who had them were anywhere near an average microwave oven in operation - we had those signs up around the office kitchenette less than 15 years ago.
As a kid we went to the University of Michigan hospital every six months for my brother.
One visit we go to the cafeteria for lunch as usual, and there were signs everywhere warning that microwave ovens were in use!
My mom asked one of the staffers what the signs were for and she told us that it turns out these new devices could affect pacemakers in a real bad way.
“We found out the hard way when a few patients went into cardiac arrest right here in the cafeteria! Took them awhile to connect the dots…”
“Oh my god,” my mom said! “Did you lose anyone?”
“Oh no honey…there ain’t no better place to have one of those than in a hospital!”
It would be years before we got one at home, and nobody we knew had a pacemaker.
Currently strong magnets can still mess with pacemakers. Fun fact, some modern phones have magnets in them that can do that - be careful about resting your phone on your chest if you have a pacemaker. I think the wireless charging unit is to blame.
That's a feature btw, not a bug. If you go to the hospital with a pacemaker malfunction or we're trying to do cardioversion in a way the pacemaker doesn't do itself the only way we can turn it off is with a big magnet. That's why most ED and cardiac units have one for an emergency.
In terms of electrical interferance, there's a lot that can go on. NFC transmits power indutively, cellular, wifi, sometimes with power sharing some you transmit electricty inducitvely too.
Apple phone's have "mag safe" which is basically a magnet. Phone also have speakers and microphones and rumble motors and compasses, all magnetic.
Could also be a radio research site, but I doubt OP wouldn't know that's where they are. If the equipment is sensitive enough to be effected by a retail microwave, they're already in a valley way outside of any town.
Someone here may have already pointed out why these warning exsisted but the pace makers that were in use back in the 70's and 80's would sometime malfunction around microwave ovens. The signs were to reduce liability.
This building was a fire station, and bunker gear is the protective clothing that firefighters wear. I guess they didn’t want you bringing dirty/smoky clothes into the break room
Bunker gear is the typical 'fire-proof' gear you see firefighters in when they might go into a burning building. Big, bulky, heavy, and often made of asbestos.
i know that even then the shielding would prevent that wavelength.. but another part of me would be terrified of a refrigerator sized microwave built in the 60s
I was gonna say, I highly doubt there was a microwave oven in the entire city in the 60s.
And you weren't kidding!
1946: The RadaRange, the first commercial microwave, was sold to restaurants, ship galleys and canteens. This six feet tall, 750 pound microwave sold for around $5,000. ($80,846 today.)
1955: Tappan made the first residential microwave, which was rarely seen in homes due to its staggering size and $1,300 price tag. ($15,294 in 2024 bucks.)
I know you guys probably already know this, but just to make it clear- just because the building was built in the 60s doesn't mean they couldn't have gotten a microwave and added a sign later :p
Jen told me the stupid science oven kills the nutrients in our food. Jen read stuff. But then Jen burned the house down after being told to not put metal in the science oven.