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Comment by spondylosaurus | Hacker News Reader

I scoured their website to look for any clues about how it might (allegedly) work and got a fat lot of nothing.

> Rest constantly monitors room air quality, using a proprietary algorithm to pinpoint any tobacco, marijuana, or nicotine presence.

So a smoke detector with an "algorithm" attached. Uh huh. How does that algorithm work?

> By analyzing various factors and patterns[...]

Some cutting edge shit here!

And as for accuracy, they don't even pretend to make promises about "99.99% success rates" or anything. This is the most detailed they get:

> Q: Is it accurate?

> A: Our sophisticated smoking detection algorithm has been tested for accuracy in real-world scenarios, backed by years of development, and tens of thousands of hours of rigorous testing and validation.

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Given that this image: https://cdn.prod.website-files.com/653a9fbd1075088b6c8f8bd3/... shows PM2.5 and CO2(ppm) it may imply they monitor particles and CO2 levels. My guess is it also monitors humidity, and temperature. Humidity helps distinguish smoke from water vapor (eg. steaming shower).

CO2 sensors are generally pretty accurate, but PM2.5 sensors are notoriously prone to false spikes usually caused by dust in or around the sensor: https://www.reddit.com/r/Awair/comments/10r1uyo/inaccurate_p... or https://forum.airgradient.com/t/unusual-pm2-5-readings-on-ne... or https://community.purpleair.com/t/what-to-do-about-incorrect...

My guess is it's likely a sensor in a hotel room accumulates dust over time, leading to high PM2.5 measurements maybe when something (eg. suitcase) bumps against the case, shaking the accumulated dust and releasing it around the sensor.

That's awesome for the hotel! The less they dust their rooms, the more "smoking fees" they can charge guests.

Note that pm2.5 will also spike when you've used shampoo, perfume, deoderant, lotion, sunblock; if you use dryer sheets and you unpack your clothes, etc.

This is news to me, but I’m unsurprised. Why people use so much strongly scented products is absolutely baffling to me.

Farts will cause it to spike

It's unfortunate that we can't comment on reviews.

Exactly! So many ways to make PM2.5 spike. I didn't even know about shampoo and sunblock. I assume for sunblock it's the spray kind?

I wonder if you could set it off by farting too much: https://www.youtube.com/watch?v=zvB0wRFebus

It's going to be similar bullshit to what Halo uses in the highschool vape sensors. A bunch of particulate sensors for like PM1, PM2.5, PM10, sniffing out VOCs, and then they consider any tripping of any of that to be a "smoke" sesh.

Edit: Oh. Rest is just NoiseAware. They're just reselling NoiseAware sensors which are just - yes - a bunch of particulate sensors hooked up to an ESP32 hooked to a web dashboard.

Yeah the anecdotal evidence leads you to this as well - the hair drier usage leading to triggering the sensor. My PM/VoC sensors in my bedroom spike when my wife dries her hair while my CO/CO2 sensors do not.

> Our sophisticated smoking detection algorithm has been tested

Okay, but what were the results? https://xkcd.com/1096/

Smokin'!

https://m.youtube.com/watch?v=KONoeHwu2pg&t=50s

I would be willing to bet a good amount of money they have a huge pile of nothing on this

On the other comment they say they monitor PM2.5, CO2 and humidity. Congratulations, your hot water shower with hard water just triggered the sensor. $500 fee.

This is like those 10k bomb detectors that were just a box with wires dangling out aren’t they?

I do not understand what possesses people to buy this stuff without proof.

Because they can charge $500 to almost all occupants realizing the likelihood of a repeat visitor is low?

You can do that without this system if you are going to do it anyway.

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