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So I was researching stuff about smoke sensors and I may be paranoid but I was wondering if they were Safe for kids and in general , I read they had infrared LEDS which I heard were very harmful for eyes if looked at directly which I assume the IR LESS are inside and nor visible outside the smoke detector but I was wondering if there was any way the LED can leak out and harm a child since they are curious and like to stare at lights/ etc.. Just got me thinking thanks for the feedback

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closed as off-topic by pipe, Michel Keijzers, Voltage Spike, Nick Alexeev Mar 19 '18 at 2:56

This question appears to be off-topic. The users who voted to close gave this specific reason:

  • "Questions on the use of electronic devices are off-topic as this site is intended specifically for questions on electronics design." – pipe, Michel Keijzers, Voltage Spike, Nick Alexeev
If this question can be reworded to fit the rules in the help center, please edit the question.

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    \$\begingroup\$ Why would IR from a battery powered device (which last years), hence ultra low power be harmful in the first place? How would it pass UL or CE mark certification if it was dangerous? \$\endgroup\$ – winny Mar 18 '18 at 8:40
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    \$\begingroup\$ There will be far more infrared light from your TV remote control. Have a look at it using your phone's camera which can see it. \$\endgroup\$ – Transistor Mar 18 '18 at 9:06
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    \$\begingroup\$ most residential smoke detectors don't use LEDs, they use a radiation source to avoid triggering on grease smoke. \$\endgroup\$ – dandavis Mar 18 '18 at 12:28
  • \$\begingroup\$ A radiation source, which is in fact, dangerous if ingested.... yet the devices themselves are generally UL and CE marked, because people shouldn't be poking around inside them. \$\endgroup\$ – djsmiley2k Mar 18 '18 at 12:39
  • \$\begingroup\$ If it's one or the other (smoke sensor with LED or no smoke sensor at all) then I'd absolutely choose smoke sensor. Any damage the sensor might possibly do over your child's lifetime is vastly outweighed by making sure you know if your house is on fire and you and your family should get out immediately. \$\endgroup\$ – BruceWayne Mar 18 '18 at 21:01
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The LED in a smoke detector is safe to look at. Not only that, but the smoke detector is constructed in such a way that the light of this LED does not actually escape the device. It is hidden away in such a way that light can't get in from the outside, as this may disturb the sensor's ability to detect the smoke. This structure works both ways, and hence the light can also not get out.

In other words, they are completely safe and your children will be far safer with a smoke detector around.

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Infrared LEDs are perfectly safe to look at. They're what are used in most remote controls, for instance, as well as on many "night vision" surveillance cameras. Some very bright infrared LEDs can be seen as very dim red light, but even these are not harmful -- and the LEDs in a smoke detector will be much smaller than that.

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    \$\begingroup\$ The only danger I can think of would be if a child took out the battery and put it in their mouth. And even that isn't especially hazardous -- more of just a surprise. \$\endgroup\$ – duskwuff Mar 18 '18 at 6:01
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    \$\begingroup\$ no, they are not safe, they contain radioactive materials you don't want a kid eating \$\endgroup\$ – dandavis Mar 18 '18 at 12:29
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    \$\begingroup\$ @dandavis -- the OP is referring to a photoelectric type smoke detector, not an ionization type \$\endgroup\$ – ThreePhaseEel Mar 18 '18 at 12:30
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    \$\begingroup\$ @ThreePhaseEel: I don't have any reason to think OP's even aware of the diff, and given the nature of the inquiry, it's worth mentioning before someone gets sick. \$\endgroup\$ – dandavis Mar 18 '18 at 12:36
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    \$\begingroup\$ "Infrared LEDs are perfectly safe to look at." - I think this is dangerously misleading; too much IR can damage the eyes just like too much visible light can, but because your eyes don't see it your body doesn't protect itself with pupil contraction or optical reflex. Sure, moderate amounts of IR (nevermind the tiny amount from the smoke sensor) won't be a problem, but if someone puts high-intensity IR LEDs right up to their eyes I'm not so sure. Please edit your answer to include at least some caution. \$\endgroup\$ – marcelm Mar 18 '18 at 20:54
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In principle, IR radiation can damage your eyes. However, that doesn't mean that the IR LED within a smoke detector (which has special form as to not let out much of the radiation at all, plus it is inside a plastic case) isn't perfectly safe. It is, by all means, perfectly safe.

The "night-vision" light used in every surveillance camera or webcam with support for enhanced "dark vision" comes from a IR LED and has, depending on model, anywhere from 500 to 2,500 times the power of the LED in a smoke detector. IR flood lights such as the one I'm using to have my garden appear bright as in daylight on the surveillance camera have more like 500,000-1,000,000 times as much.
None of these damage your eyes (though the latter does irritate night-active insects as they can see the light, alas it also irritates burglars, which is more important to me).

IR light used to be, once upon a time when safety at work was written in small caps, a known source of eye disorders with metal workers. But here, we're talking about, I don't know, 100 billion times the radiation intensity of my garden flood light, and exposure over years.
That's nowhere near comparable to the intensity of what's inside a well-sealed smoke detector.

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  • \$\begingroup\$ Do you have sources for the claim that IR radiation can damage your eyes? I'd think that any source releasing enough IR to be dangerous will be so hot and close that it's dangerous anyhow, even without the IR. \$\endgroup\$ – Eric Duminil Mar 18 '18 at 19:51
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    \$\begingroup\$ @EricDuminil an obvious example is IR lasers. No heat, and the distance doesn't matter as they have a collimated beam \$\endgroup\$ – Chris H Mar 18 '18 at 20:21
  • \$\begingroup\$ @EricDuminil Given you can melt solder with IR (e.g. infrared reflow oven), you can also cook your eyes too. But that takes an awful lot more energy than you can get out of a smoke detector. \$\endgroup\$ – Tom Carpenter Mar 18 '18 at 21:48
  • \$\begingroup\$ @EricDuminil I would not suggest looking at the sun through a strong magnifying glass either. That would probably be quite painful, even though the IR emitter is far far away and not dangerously hot. \$\endgroup\$ – MrGerber Mar 19 '18 at 7:31
  • \$\begingroup\$ @MrGerber: By using a magnifying glass, you make the sun "closer" and hotter to your eye. It's also not 100% IR. \$\endgroup\$ – Eric Duminil Mar 19 '18 at 8:07

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