6 ms·

A little tangential, but are these things safe for humans? I have a couple of LD2410 devices and I’d like to use one of them with ESPHome in the bedroom. I did

by 037 2y ago

A little tangential, but are these things safe for humans? I have a couple of LD2410 devices and I’d like to use one of them with ESPHome in the bedroom. I did some research and they seem to be very low power and safe, but you know, before sleeping with a radar pointing at us all night long, I’m looking for as much feedback as possible.

05 2y ago
Some phones have a SAR of almost 2W/kg, compared to that milliwatts of 10GHz RF are nothing. Not to mention that with standard energy dissipation formula of E~R^(-2) you're getting into microwatts at any practical distance from the antenna.
t0mas88 2y ago
I have these all around the house, but not in the bedrooms. I use weight sensors to detect that someone is in bed and traditional PIR for motion in bedrooms. Probably overly careful, but I didn't want to point a radar at my sleeping kids (and myself) for 12 hours per day. Similar for the WiFi access point upstairs, it's only in the hallway and not at maximum power.
- 037 2y ago
  I agree with you, especially regarding children and anyone who hasn’t explicitly made this choice, which is why I asked the question. The only thing is, I suspect we get scared by certain words, like “radar” and “microwaves”, and then we might spend all day with our heads next to a Wi-Fi router or a phone constantly downloading files on 4G. For example: maybe the ESP32 transmitting the bed weight exposes us to more danger than the radar sensor (that can also be placed very far from the bed)? Maybe with our smartphones charging on the nightstand too. I’m not a big fan of fear-based, illogical decisions. But, again, I understand perfectly.
- Avamander 2y ago
  > Probably overly careful, but I didn't want to point a radar at my sleeping kids (and myself) for 12 hours per day. While I understand the sentiment. It's very very unlikely to be dangerous and there are plenty of other environmental dangers. The biggest being the sun. But the most common man-made ones are probably auditory. Like toys and TVs being too loud or high-frequency sounds blasted from speakers in malls or under bridges to avoid "loitering."
  - davidwritesbugs 2y ago
    Loud toys are definitely dangerous for my children, they make me angry.
  - moffkalast 2y ago
    Yeah on one hand you have people afraid of wifi and simultaneously sending their kids to play all day outside in UV index 11 without a hat or sunscreen. Things that are "natural" being inherently safe and anything technological literally death itself.
perlgeek 2y ago
Non-ionizing radio waves are generally safe for humans. The only mechanism besides ionization that could harm humans is through the transfer of lots of power into the human body (think soldiers keeping themselves warm by stepping in front of a radar emitter). So let's try to do a ballpark estimate of how much that could matter. I haven't found (from a quick search) any data regarding the transmission power, but the data sheet at https://fcc.report/FCC-ID/2AD56HLK-LD2410B-P/6620025.pdf https://fcc.report/FCC-ID/2AD56HLK-LD2410B-P/6620025.pdf says the average current consumption is 79mA at 5V, which means it uses 0.4W. How much of that is actually transmitted? I'd guess 10%-50% (likely much less, but let's go with this more conservative estimate, from a safety perspective), so now we're in the range of 40mW to 200mW. If you absorb 1/4th of that (again, somewhat conservative estimate; you'll likely also reflect some, and most of it is going to pass you), we're at 10mW to 50mW extra power that is absorbed by your tissue. Again, this is a super high (and thus for our purpose, conservative) estimate. Somebody else in this thread mentioned microwatts being absorbed, which sounds much more plausible. To put this into context, the base level of power that an adult human operates on at rest is about 100W. This is a factor of 500 to 2500 more than the power absorbed from our millimeter wave radar. Unless all the absorption happens by a very specific and sensitive part of the body (like your eyes or so), this should just be background noise. If you want another perspective, you could try to compare it with whatever radiation (both RF and heat) that your phone emits, that you likely carry in your pocket for hours at a time.
- lpcvoid 2y ago
  >soldiers keeping themselves warm by stepping in front of a radar emitter Holy, did people actually do this? A quick search yielded no results. Not sure if thankful or not.
  - simondanerd 2y ago
    Works, it's a weird feeling, speaking from experience. HF antennas can give some respectable burns too. But the effects are debated and not entirely scientific: https://www.reddit.com/r/army/comments/13r6hod/i_keep_being_told_signaliers_only_have_daughters/ https://www.reddit.com/r/army/comments/13r6hod/i_keep_being_...
rpaddock 2y ago
The site Microwave News keeps up on the latest health aspects of such things. https://www.microwavenews.com https://www.microwavenews.com

by 037 2y ago

05 2y ago

Some phones have a SAR of almost 2W/kg, compared to that milliwatts of 10GHz RF are nothing. Not to mention that with standard energy dissipation formula of E~R^(-2) you're getting into microwatts at any practical distance from the antenna.

t0mas88 2y ago

I have these all around the house, but not in the bedrooms. I use weight sensors to detect that someone is in bed and traditional PIR for motion in bedrooms. Probably overly careful, but I didn't want to point a radar at my sleeping kids (and myself) for 12 hours per day. Similar for the WiFi access point upstairs, it's only in the hallway and not at maximum power.

037 2y ago
I agree with you, especially regarding children and anyone who hasn’t explicitly made this choice, which is why I asked the question. The only thing is, I suspect we get scared by certain words, like “radar” and “microwaves”, and then we might spend all day with our heads next to a Wi-Fi router or a phone constantly downloading files on 4G. For example: maybe the ESP32 transmitting the bed weight exposes us to more danger than the radar sensor (that can also be placed very far from the bed)? Maybe with our smartphones charging on the nightstand too. I’m not a big fan of fear-based, illogical decisions. But, again, I understand perfectly.
Avamander 2y ago
> Probably overly careful, but I didn't want to point a radar at my sleeping kids (and myself) for 12 hours per day. While I understand the sentiment. It's very very unlikely to be dangerous and there are plenty of other environmental dangers. The biggest being the sun. But the most common man-made ones are probably auditory. Like toys and TVs being too loud or high-frequency sounds blasted from speakers in malls or under bridges to avoid "loitering."
- davidwritesbugs 2y ago
  Loud toys are definitely dangerous for my children, they make me angry.
- moffkalast 2y ago
  Yeah on one hand you have people afraid of wifi and simultaneously sending their kids to play all day outside in UV index 11 without a hat or sunscreen. Things that are "natural" being inherently safe and anything technological literally death itself.

perlgeek 2y ago

Non-ionizing radio waves are generally safe for humans. The only mechanism besides ionization that could harm humans is through the transfer of lots of power into the human body (think soldiers keeping themselves warm by stepping in front of a radar emitter). So let's try to do a ballpark estimate of how much that could matter. I haven't found (from a quick search) any data regarding the transmission power, but the data sheet at https://fcc.report/FCC-ID/2AD56HLK-LD2410B-P/6620025.pdf https://fcc.report/FCC-ID/2AD56HLK-LD2410B-P/6620025.pdf says the average current consumption is 79mA at 5V, which means it uses 0.4W. How much of that is actually transmitted? I'd guess 10%-50% (likely much less, but let's go with this more conservative estimate, from a safety perspective), so now we're in the range of 40mW to 200mW. If you absorb 1/4th of that (again, somewhat conservative estimate; you'll likely also reflect some, and most of it is going to pass you), we're at 10mW to 50mW extra power that is absorbed by your tissue. Again, this is a super high (and thus for our purpose, conservative) estimate. Somebody else in this thread mentioned microwatts being absorbed, which sounds much more plausible. To put this into context, the base level of power that an adult human operates on at rest is about 100W. This is a factor of 500 to 2500 more than the power absorbed from our millimeter wave radar. Unless all the absorption happens by a very specific and sensitive part of the body (like your eyes or so), this should just be background noise. If you want another perspective, you could try to compare it with whatever radiation (both RF and heat) that your phone emits, that you likely carry in your pocket for hours at a time.

lpcvoid 2y ago
>soldiers keeping themselves warm by stepping in front of a radar emitter Holy, did people actually do this? A quick search yielded no results. Not sure if thankful or not.
- simondanerd 2y ago
  Works, it's a weird feeling, speaking from experience. HF antennas can give some respectable burns too. But the effects are debated and not entirely scientific: https://www.reddit.com/r/army/comments/13r6hod/i_keep_being_told_signaliers_only_have_daughters/ https://www.reddit.com/r/army/comments/13r6hod/i_keep_being_...

rpaddock 2y ago

The site Microwave News keeps up on the latest health aspects of such things. https://www.microwavenews.com https://www.microwavenews.com