Cell phones been found to increase skin temperature, but what causes the rise?

[sadpatato-897]

Mobile phones have been found to increase skin and brain temperature, sometimes the increase was as bad as 4.5 degrees C. But how much (if any) of that could be down to radiation, and how much down to battery discharge? I’ve only read two studies that have looked into comparing phone battery discharge and radiation. Both done two rounds of tests, one where subjects would hold a phone to their head for a 5 minutes, with the phone in normal mode (communications on). The second round was done the same but with the phone in airplane/standby mode (communications off/battery life saving).

Both studies found that the temperature was higher in normal mode then it was in airplane mode, hinting that radiation rose the skin temperature, as well as the battery. However, in normal mode the battery would be used more, therefore it’ll be more warm, where as in airplane/standby mode the battery would be used less, and in one of the studies standby mode would put the phone into a power saving mode, therefore less battery power would be used and less heat generated. Am I correct in thinking that this is a poor way of telling if battery power or radiation causes temperature rise?

[swansont]

“Our results suggest that direct RF heating of the skin only contributes a small part of the temperature rise and that most is due to heat conduction from the handset.”

It’s in the abstract of your link.

If you put a warm slab of material next to your skin, the skin temperature will go up. Conduction and insulation.

[sadpatato-897]

7 minutes ago, swansont said:

“Our results suggest that direct RF heating of the skin only contributes a small part of the temperature rise and that most is due to heat conduction from the handset.”

It’s in the abstract of your link.

If you put a warm slab of material next to your skin, the skin temperature will go up. Conduction and insulation.

Yeah, but as I said they compared RF heating to battery heating in a way that I can see as being possibly problematic, and I wanted to know if my assesment was correct.

[swansont]

35 minutes ago, sadpatato-897 said:

Yeah, but as I said they compared RF heating to battery heating in a way that I can see as being possibly problematic, and I wanted to know if my assesment was correct.

What’s problematic about it?

Quote

Both studies found that the temperature was higher in normal mode then it was in airplane mode, hinting that radiation rose the skin temperature, as well as the battery.

When a computer’s processor is running, it heats up. It’s not the battery, as such. It’s the current, and resistive heating.

[sadpatato-897]

15 minutes ago, swansont said:

What’s problematic about it?

Studies looked into if battery discarge or RF radiation caused high skin tempreture (like, the battery gets hot which raises temperature). They tried to account for this by doing one round of study with the phone in ‘normal’ mode, and another with the phone in airplane mode (communication disabled). They found that it was worse amount normal mode, which hints that the radiation causes temperature rise. However, in normal mode the battery is in full use, but in airplane it goes into saving mode, so the discharge is less and therefore the temperature is less. I guess this means the whole heating course could be down to a hot battery, as in normal mode the battery is in use more and therefore is hotter than in airplane mode, where the battery is used less. So, the difference between normal and airplane mode could just be down to different battery settings/use, not radiation. Am I right?

 

 

Edited January 17, 2021 by sadpatato-897

[swansont]

57 minutes ago, sadpatato-897 said:

Studies looked into if battery discarge or RF radiation caused high skin tempreture (like, the battery gets hot which raises temperature).

They don’t say anything about a battery in that abstract, but OK. It heats up when the circuit is drawing current.

 

57 minutes ago, sadpatato-897 said:

They tried to account for this by doing one round of study with the phone in ‘normal’ mode, and another with the phone in airplane mode (communication disabled). They found that it was worse amount normal mode, which hints that the radiation causes temperature rise.

No, that’s not a valid conclusion. The processor is not doing as much in airplane mode. It’s not just the RF from pinging the tower.

”transmitting at full power (+2.6 degrees C) and in stand-by mode (+2.0 degrees C)” puts a limit on the RF contribution, and it’s no more than 0.6 degrees out of the 2.6, which agrees with their conclusion that RF is a small contributor 

 

57 minutes ago, sadpatato-897 said:

However, in normal mode the battery is in full use, but in airplane it goes into saving mode, so the discharge is less and therefore the temperature is less. I guess this means the whole heating course could be down to a hot battery, as in normal mode the battery is in use more and therefore is hotter than in airplane mode, where the battery is used less. So, the difference between normal and airplane mode could just be down to different battery settings/use, not radiation. Am I right?

Yes. Notice that this summary is not consistent with your earlier one.

[sadpatato-897]

6 minutes ago, swansont said:

They don’t say anything about a battery in that abstract, but OK. It heats up when the circuit is drawing current.

 

No, that’s not a valid conclusion. The processor is not doing as much in airplane mode. It’s not just the RF from pinging the tower.

”transmitting at full power (+2.6 degrees C) and in stand-by mode (+2.0 degrees C)” puts a limit on the RF contribution, and it’s no more than 0.6 degrees out of the 2.6, which agrees with their conclusion that RF is a small contributor 

 

Yes. Notice that this summary is not consistent with your earlier one.

Thanks!! so I’m right in my assessment?

[Sensei]

Any object emits photons with energy depending on temperature (blackbody radiation). But if temperature is equal to environment, object receives (absorbs) similar amount of energy in photons (and other ways) as it emits therefore illusion of lack of radiation ("equilibrium"). But if you will put object with room ambient temperature to e.g. refrigerator it will be emitting more than receiving back and cool down even more.

Turned off smartphone, or totally broken smartphone also emits radiation. If you would put it in refrigerator and observe by IR camera you would see the difference (photons in IR and MW spectrum) and how it slowly goes from ambient room temperature 20-25 C to below 0 C, emitting less and less energetic photons. You could repeat with even lower refrigerator temperatures with liquid Nitrogen and get to even lower energetic photons from blackbody radiation.

Edited January 17, 2021 by Sensei

[MigL]

Typical power output of a cell phone is 0.6W ( old analog phones did 3W ); probably less than what 'leaks' from your microwave, so probably due to conduction heating, not radiative.
Either way, you're on your phone too long

[sadpatato-897]

 

Edited January 18, 2021 by sadpatato-897

[John Cuthber]

21 hours ago, sadpatato-897 said:

how much (if any) of that could be down to radiation, and how much down to battery discharge?

No radio transmitter is better than 50% efficient. (The rest is wasted as heat)
No battery is perfectly efficient. (Some energy is lost as heat)

Some of the RF signal escapes to make contact with other phones. (and so it can't be dissipated in the skin as heat.)

So it's clear that most of the heating can not possibly come from the radiation.

Incidentally, if I had a pair of gloves that reliably kept my fingers 5 degrees above ambient, I'd be quite pleased.

[swansont]

27 minutes ago, John Cuthber said:

No radio transmitter is better than 50% efficient. (The rest is wasted as heat)

And at least half the radiation is going to be sent in a different direction than the face. The phones work, after all.

[John Cuthber]

4 hours ago, swansont said:

And at least half the radiation is going to be sent in a different direction than the face. The phones work, after all.

 

5 hours ago, John Cuthber said:

Some of the RF signal escapes to make contact with other phones.

There's no guarantee that it's half, but it must be some.
If it was less than half, that would imply a really bad design, but if the proposal is that phones are bad for you, a really bad design is one of the initial assumptions.

[pfuggs]

On 1/17/2021 at 12:24 PM, swansont said:

“Our results suggest that direct RF heating of the skin only contributes a small part of the temperature rise and that most is due to heat conduction from the handset.”

It’s in the abstract of your link.

If you put a warm slab of material next to your skin, the skin temperature will go up. Conduction and insulation.

I find this so interesting as to how our bodies react to stimulation. A podcast I have been listening to promotes a device that helps people with temperature regulation simply by emitting a cooling or heating effect which really does help people adjust to uncomfortable temperatures. Mind over matter or whatever. 

[Phi for All]

13 minutes ago, pfuggs said:

I find this so interesting as to how our bodies react to stimulation. A podcast I have been listening to promotes a device that helps people with temperature regulation simply by emitting a cooling or heating effect which really does help people adjust to uncomfortable temperatures. Mind over matter or whatever. 

!

Moderator Note

The topic target is cell phones, not any random device. If you joined to promote this device, that's against the rules you agreed to. Please stay on topic.

 

[pfuggs]

I was just remarking 🙄