So you’re running late for work and you’re taking the elevator up to the 14th floor.
Next thing you know, someone walks in while talking on their mobile phone.
Nothing unusual right?
Suddenly, the guy next to you gets all wound up and yells “Don’t you know that you
shouldn’t use a phone in an elevator?
You’re going fry our brains with the radiation!”
This isn’t just a made up story.
I’ve seen signs next to elevators telling people not to use their mobile phone in an
elevator.
Buy why?
Is it true that mobile phone radiation is amplified in elevators?
And could this cause health problems like brain tumours?
Let’s find out
Before we get to elevators, let’s look at how mobile phones work in the first place.
Let’s say you call your Uncle to invite him to a family Christmas party.
While you’re talking, a microphone listens to your voice and a small processing unit
converts your voice into a digital signal.
This digital signal needs to get to your uncle, but how can this be done without a wire connecting
the two phones?
Well the antenna converts the digital signal of your voice into electromagnetic waves that
can be transmitted wirelessly.
To transmit this information, cell phones use the microwave part of the electromagnetic
spectrum.
Microwaves have higher energy than radio waves, but less energy than infrared or visible light.
The microwaves from your mobile phone aren’t strong enough to get to your uncle directly.
Instead they are sent to the closest base station.
These base stations ‘listen’ to microwaves sent from your phone and send the signal though
land based phone cables to a base station that’s closest to your uncle.
This second base station converts the signal back into microwaves, and sends them to your
Uncle’s phone.
Your Uncle’s phone’s antenna picks up the microwaves and converts them back into
a voice signal that he can listen to.
Amazingly, all of this happens while you argue about who’s going to wear the Santa outfit
this year.
So what do we know about microwave radiation, and could it be harmful?
Microwaves are all around us.
Have you heard of the Cosmic Microwave Background Radiation?
This is faint microwave radiation that is thought to have resulted from the Big Bang
and is present throughout all of space.
The sun also emits microwaves, although most of it is blocked by the earth’s atmosphere.
So how do microwaves effect our body?
Well the main effect is the ‘thermal effect’ of microwaves.
When exposed to enough high power microwave radiation, molecules start to move faster,
and this generates heat.
This is the principle that is used when heating up food in a microwave oven – water molecules
in food move faster and the heat produced by this vibration warms up your food.
We know that the microwave radiation from your phone is too weak to cause any significant
heat generation.
But what about non-thermal effects?
For example, we know that when using a mobile phone, the head gets more radiation than the
rest of the body.
So is it possible mobile phones could cause brain tumours?
Well there are two ways we can answer this question: we can to do experiments in the
lab or do experiments on humans.
We know that the first step in the development of cancer is damage to our DNA.
Most lab studies have shown that microwaves cannot damage our DNA.
So this has been reassuring.
There has been one experiment that exposed rats and mice to astronomical amounts of microwave
radiation and there were some health effects but only in male rats.
Interestingly, there were no health effects seen in female rats, male mice and female
mice.
Overall, scientists are not convinced that this result applies in humans.
But the good thing is that it has made scientists more vigilant about the potential health effects
of microwaves.
So what about studies in humans?
Well obviously we can’t experiment on humans directly.
Instead, scientists have been using other indirect techniques to study the effect of
microwaves on our health.
Some researchers gathered people with and without brain tumours, and asked them to remember
how much they used their cell phone.
This is called a case-control study and as you can imagine, the results from these kind
of studies are very difficult to interpret.
This is because this kind of study relies on people’s memories from what they’ve
done years ago, and I can barely remember what I had for breakfast last Saturday!
Still most of these types of studies have not shown a consistent relationship between
mobile phone use and brain tumours.
Another technique is to look at the number of people being diagnosed with brain tumours
and see if this is increasing.
We know that the number of people using mobile phones has increased dramatically over the
last twenty years, so if mobile phones do cause cancer, we should see an increased number
of people being diagnosed with brain tumours.
An Australian study of this type was published in November 2018.
It confirmed that there has been a massive increase in the number of people using mobile
phones from 1990 onwards.
But brain tumour rates have remained stable.
Even with a follow up period of 15 years, there hasn’t been any significant increase
in brain tumour rates.
So as far as we can tell, microwaves from mobile phones don’t cause brain tumours.
A key safety mechanism that helps protect us, is that there are strict international
limits so that mobile phones only emit very low amounts of microwave radiation.
In normal use, mobile phones never really reach this safety limit.
They normally only emit 35%.
But there are some circumstances when the radiation level from mobile phones could get
to the full limit, and that’s where the elevator situation comes into play.
While you’re talking on your phone in an elevator, your mobile is still trying to communicate
with the base station, but the microwaves are blocked by the metal construction of the
elevator, the thick concrete that makes up the elevator shaft and all the concrete and
steel rods in the main building.
To compensate for this, mobile phones increase the power of microwaves in a desperate attempt
to maintain a connection to the base station.
Also, the elevator is essentially a big metal box, so microwaves can reflect off the walls
and become trapped.
Both of these factors mean that amount of microwave radiation in an elevator can increase
dramatically compared to normal cell phone use.
In computer simulations of this kind of situation, the maximum amount of radiation in an elevator
can exceed the safety limit by about 3.8%.
This won’t fry your brain, but it’s still more microwave radiation than you need to
be exposed to.
So overall, it’s a good idea not to use your mobile phone while you’re in an elevator.
I mean you’ll get terrible reception and be exposed more microwaves.
Neither of these sound like a good deal.
But one thing that struck me while researching this video, is why we worry so much about
the theoretical effects of mobile phones, when there are so many real risks associated
with cell phone use.
Have you seen someone crossing the road while texting?
Or maybe you’ve seen someone driving along the freeway while looking down on their phone?
It only takes a split second of distraction for there to be a serious accident.
So the next time you pull out your phone to send a text or make a phone call, maybe just
take a second to make sure that you’re not putting yourself or others in danger.
If you’re interested in more tech related videos, the video on your right talks about
the health effects of infrared radiation from things like Face ID and Iris Scanning.
Thanks for watching and I’ll see you in the next one.