Reverse engineering Xiaomi air purifier NFC stickers • Hacker News Board

Re: Reverse engineering Xiaomi air purifier NFC stickers

#21

Post by GekkePrutser » Sat, May 28, 2022, 3:40 PM UTC

chmars wrote: post #7

GekkePrutser wrote: post #5

Earlier quoted context omitted.

I have one and it tracks very poorly. It tracks only the usage time regardless of how fast the fan is running. When on auto, it is mostly spinning at idle, hardly sucking air through the filter, and as such it's hardly contaminating the air filter (in fact the airflow is so low I stopped using auto mode at all, there is just no point). It also doesn't take into account how contaiminated the ambient air is (even thoug…

In automatic mode, different ppm level should result in higher fan speeds. That is at least the case with my filters. Cooking for example can be a trigger. You are of course right that automatic mode does not do much. At the same time, higher fan speeds are noticeable (and annoying).

For my environment it never ramps up in that mode at all. Ambient levels are never higher than 10ppm or so.

I know the sensor works because once there was a small bin fire outside. There was no visible smoke indoors, I only noticed a slight smell. But the purifier immediately ramped up and showed over 200ppm.. So it does work.

I'm surprised it's so low as I live at the 2nd floor on a fairly busy street with many diesel buses passing.

Re: Reverse engineering Xiaomi air purifier NFC stickers

#22

Post by throwaway290 » Sat, May 28, 2022, 3:45 PM UTC

iSloth wrote: post #11

I've never experienced an air purifier, what's the general consensus? Do they make a difference? Perhaps a placebo? A must have? Genuinely interested if I'm missing out - For what it's worth I do live right on a main road in the UK, so I expect there is some level of pollution in the air.

There is no level of pm2.5 that is considered safe to breathe, and it is easy to find out levels in your area so make your own call based on that.

It will be a placebo if your home cannot be isolated from outside air or if you don't make an effort to keep windows closed when air is bad.

Also, many expensive purifiers are overpriced junk compared to even simple DIY solutions like those found on particlecounting Tumblr and similar. Ideally the first thing to do is get some reputable air quality monitors.

Re: Reverse engineering Xiaomi air purifier NFC stickers

#23

Post by DragonStrength » Sat, May 28, 2022, 3:50 PM UTC

iSloth wrote: post #11

I've never experienced an air purifier, what's the general consensus? Do they make a difference? Perhaps a placebo? A must have? Genuinely interested if I'm missing out - For what it's worth I do live right on a main road in the UK, so I expect there is some level of pollution in the air.

The biggest effect is in homes without any sort of central air system, which would usually include various levels of filters up to HEPA and UV systems at this point. During the worst of fire season in the Bay Area though, a single Coway HEPA filter, basically a box fan with a HEPA filter strapped to it, kept my apartment in the "safe" range for AQI. Just stepping out my apt front door into the hallway I'd be hit with the heavy stench of smoke.

Truly remarkable how well they work, but whether you need one or not depends on whether you have allergens/pollution as an issue in your home. You can purchase an air quality monitor (I have a Temtop M10) or check online measurements of AQI, pollen, etc. for your area. If you have an issue, they work, but not everyone has an issue.

Re: Reverse engineering Xiaomi air purifier NFC stickers

#24

Post by jaqalopes » Sat, May 28, 2022, 3:50 PM UTC

iSloth wrote: post #11

I've never experienced an air purifier, what's the general consensus? Do they make a difference? Perhaps a placebo? A must have? Genuinely interested if I'm missing out - For what it's worth I do live right on a main road in the UK, so I expect there is some level of pollution in the air.

Ancedotally they work 100%. Not only do they remove noticeable odors, they suck up tons of allergenic dust and invisible particulates that can mess with your breathing (if you have a sensitive respiratory system).

Non-anecdotally, I've heard it claimed that indoor air pollution is the #1 factor in reducing the lifespans of otherwise healthy people. No idea if this is the case or what the evidence is, but I don't find it hard to believe.

Re: Reverse engineering Xiaomi air purifier NFC stickers

#25

Post by techwiz137 » Sat, May 28, 2022, 3:54 PM UTC

DragonStrength wrote: post #23

iSloth wrote: post #11

I've never experienced an air purifier, what's the general consensus? Do they make a difference? Perhaps a placebo? A must have? Genuinely interested if I'm missing out - For what it's worth I do live right on a main road in the UK, so I expect there is some level of pollution in the air.

The biggest effect is in homes without any sort of central air system, which would usually include various levels of filters up to HEPA and UV systems at this point. During the worst of fire season in the Bay Area though, a single Coway HEPA filter, basically a box fan with a HEPA filter strapped to it, kept my apartment in the "safe" range for AQI. Just stepping out my apt front door into the hallway I'd be hit with…

Okay so I bought a cheap-ish Air Purifier, now because the brand is...I think it's Chinese(Rohnsonn), I can't determine if it really does anything, if these filters do anything at all to improve my air quality and if the UV light is even strong enough to kill germs. Is there a way to verify it's effectiveness?

Re: Reverse engineering Xiaomi air purifier NFC stickers

#26

Post by dxhdr » Sat, May 28, 2022, 3:56 PM UTC

iSloth wrote: post #11

I've never experienced an air purifier, what's the general consensus? Do they make a difference? Perhaps a placebo? A must have? Genuinely interested if I'm missing out - For what it's worth I do live right on a main road in the UK, so I expect there is some level of pollution in the air.

> Do they make a difference? Perhaps a placebo? A must have?

Purchase an air quality monitor, something like the Dylos DC1100. Then run a HEPA filter in a closed room for 30 minutes. It will remove almost all particulates! They work extremely well. Whether it "makes a difference" for your health is less clear.

Re: Reverse engineering Xiaomi air purifier NFC stickers

#27

Post by teaearlgraycold » Sat, May 28, 2022, 3:57 PM UTC

phphphphp wrote: post #13

iSloth wrote: post #11

I've never experienced an air purifier, what's the general consensus? Do they make a difference? Perhaps a placebo? A must have? Genuinely interested if I'm missing out - For what it's worth I do live right on a main road in the UK, so I expect there is some level of pollution in the air.

I (in London) bought one recently (a COWAY Airmega) to try and improve the air quality in my apartment, specifically, the dust which has been reeking havoc on my breathing because of allergies. There is a noticeable improvement but it has not solved the problem by any stretch: so while I don’t regret the purchase, and will keep using it, I am not how sure I’d recommend them for the someone without breathing difficult…

I got the same one and it’s amazing for California when the air is smokey.

Re: Reverse engineering Xiaomi air purifier NFC stickers

#28

Post by CoastalCoder » Sat, May 28, 2022, 4:03 PM UTC

hammock wrote: post #15

iSloth wrote: post #11

I've never experienced an air purifier, what's the general consensus? Do they make a difference? Perhaps a placebo? A must have? Genuinely interested if I'm missing out - For what it's worth I do live right on a main road in the UK, so I expect there is some level of pollution in the air.

I was so skeptical. Living in SF in 2018(?) during the wildfires, my apartment was drafty and I’d come home from work to a hazy indoor environment. I’d wake up with a sore throat and that’s what got me to take action (can’t sleep with an n95 on) I got the cheapest air purifier from Amazon and just put it on my bedside table. After one night my sore throat was gone. As simple as these machines are, they do work.

I can see how an air purifier makes sense in that 2018 scenario.

I guessing that the benefits are less certain in more typical cases.

Re: Reverse engineering Xiaomi air purifier NFC stickers

#29

Post by hammock » Sat, May 28, 2022, 4:08 PM UTC

CoastalCoder wrote: post #28

hammock wrote: post #15

Earlier quoted context omitted.

I was so skeptical. Living in SF in 2018(?) during the wildfires, my apartment was drafty and I’d come home from work to a hazy indoor environment. I’d wake up with a sore throat and that’s what got me to take action (can’t sleep with an n95 on) I got the cheapest air purifier from Amazon and just put it on my bedside table. After one night my sore throat was gone. As simple as these machines are, they do work.

I can see how an air purifier makes sense in that 2018 scenario. I guessing that the benefits are less certain in more typical cases.

The benefits, yes. Those would be dependent on the local environment and if it’s causing you specific suffering. But that experience sold me on the functionality at least.

Re: Reverse engineering Xiaomi air purifier NFC stickers

#30

Post by DragonStrength » Sat, May 28, 2022, 4:09 PM UTC

techwiz137 wrote: post #25

DragonStrength wrote: post #23

Earlier quoted context omitted.

The biggest effect is in homes without any sort of central air system, which would usually include various levels of filters up to HEPA and UV systems at this point. During the worst of fire season in the Bay Area though, a single Coway HEPA filter, basically a box fan with a HEPA filter strapped to it, kept my apartment in the "safe" range for AQI. Just stepping out my apt front door into the hallway I'd be hit with…

Okay so I bought a cheap-ish Air Purifier, now because the brand is...I think it's Chinese(Rohnsonn), I can't determine if it really does anything, if these filters do anything at all to improve my air quality and if the UV light is even strong enough to kill germs. Is there a way to verify it's effectiveness?

I'd look at what the purifier claims to eliminate and find a quality monitor that will give you a reading. Most are portable, so you can compare to outdoor values directly. You're going to need some baseline to compare to though. If you have an AQI in the safe range already in your home, you'd have to contrive some actual experiments or find someone who already has.

I'll say I'm pretty distrustful of anything but filters personally. My mom purchased a purifier at one point which claimed to use UV light to purify but had no fan to actually pull air through the light, so obviously, it wasn't doing anything.