8 ms·

Air Quality Monitors from USD $169 to $6k use the same low-cost PM Modules

152 points by ahaucnx 3y ago

nikisweeting 3y ago
This is the best one I've seen: https://boseansafety.com/products/air-quality-monitor-home-t-z01 https://boseansafety.com/products/air-quality-monitor-home-t... It's by an industrial mining supply company instead of a consumer goods company, and seems to be more accurate than the cheap Amazon options I tried.
- jondwillis 3y ago
  Invalid SSL cert, ironic for that domain name! edit) nevermind, on public wifi
  - dewey 3y ago
    Works for me on iOS Safari, maybe something on your end?
  - TonyTrapp 3y ago
    No issues here with the certificate (Firefox / Windows).
  - sinuhe69 3y ago
    It uses a certificate issued by Let's Encrypt, so you might need to update your root certificates list.
- lysp 3y ago
  This seems to look very similar to generic ali express sensors: ie. Quick search: https://www.aliexpress.com/item/1005005944910617.html https://www.aliexpress.com/item/1005005944910617.html Generally things without user manuals, or proper specifications are either directly from there, or rebadged from there.
  - dahart 3y ago
    Ali express has the Bosean, and the specs appear to be different from the link you found. https://www.aliexpress.us/item/3256803168407076.html https://www.aliexpress.us/item/3256803168407076.html I see multiple knock-offs of the version you linked, the packaging looks different than the Bosean. Is the lack of a brand or company name printed on the device a potential clue about which one’s a knock-off?
- pxx 3y ago
  It seems unlikely it has a true CO2 sensor for that price point (it could, but the bom price of just the module is over $20). The co2 "equivalent" from VOC sensors is pretty crappy in my experience.
  - bananapub 3y ago
    while true that actual CO2 sensors are expensive, this device doesn't even claim to have one
    - mikestew 3y ago
      Scroll down, and it shows a CO2 measurement on the screen.
remlov 3y ago
̶>̶ ̶̶1̶6̶9̶.̶0̶0̶ ̶t̶o̶ ̶6̶.̶0̶0̶0 ̶U̶S̶D̶.̶̶ Title was corrected. Kit costs 138.00, fully assembled costs even more.
- ahaucnx 3y ago
  The range is up to six thousand dollars, not six dollars.
  - remlov 3y ago
    I stand corrected. The period in 6.000 in place of a comma threw me off.
- LeifCarrotson 3y ago
  The current edition of the "kit" is just a pre-soldered PCB, a plastic case, and some screws, it's basically a complete product. The original DIY basic or pro kit are also close to complete - basically dropping some dev boards on 0.1" headers onto the PCB (and a USB-C connector, and 1.25mm pitch PM sensor cable, slightly harder). You can also get just the bare sensor from a reputable distributor for $40: https://www.adafruit.com/product/3686 https://www.adafruit.com/product/3686 Or get the same sensor from overseas for about $12. I just built the AirGradient DIY Pro kit (no longer listed for sale on the website?), it's remarkable how PM and CO2 spike through the whole house when we cook on our natural gas stove - been waffling on that induction cooktop, but it's probably time! Still need to get the TVOC/NOx module to add to it...
  - remlov 3y ago
    Looking closer, this is probably a cheaper much more feature rich alternative to the aranet4 I've got.
    - ahaucnx 3y ago
      The AirGradient also uses a SenseAir CO2 Sensor like the Aranet but also measures additionally PM and TVOCs.
ahaucnx 3y ago
Author here. I'm planning to do some more comparison testing of PM modules and planning to benchmark modules from Sensirion, Plantower, Cubic and AlphaSense. Let me know if you know some other sensor modules that could be interesting. I think this could be a pretty interesting follow up post.
- agloe_dreams 3y ago
  I do wonder where the VINDSTYRKA sits...though I kinda imagine that if anyone beats your price point per quality you probably wouldn't actually say.
  - ahaucnx 3y ago
    The VINDSTYRKA does not contain a CO2 module which is the most expensive part of the BOM, so it's not directly comparable. For this blog post I only looked at the monitor tested by AQ-Spec [1] and the Ikea one is not in their list. [1] https://www.aqmd.gov/aq-spec/evaluations/criteria-pollutants/summary-pm https://www.aqmd.gov/aq-spec/evaluations/criteria-pollutants...
    - clairity 3y ago
      no one should worry about CO₂ at all in their homes or offices. only workers in certain industries/factories, where CO₂ can get several orders of magnitude higher, need to be concerned at all about it. you (here and in your marketing materials) are stoking needless anxiety over a gas that life on earth literally requires. pollutants, on the other hand, and particularly particulate matter (especially chemicals that we've manufactured recently in human history), do have proven negative health consequences and should be monitored and mitigated in the home and office. it's estimated that over a million people a year die prematurely of respiratory and cardiovascular complications due to pollution. in short, a lack of CO₂ monitoring in favor of PM and VOCs by ikea should be seen as a plus, not a minus here. note that VOCs are typically estimated from cheap CO₂ sensors, and are likely to be highly unreliable as a result, but more accurate (and more expensive) VOC sensing is possible, e.g., https://www.degruyter.com/document/doi/10.1515/revac-2021-0127/pdf https://www.degruyter.com/document/doi/10.1515/revac-2021-01...
emmanuel_1234 3y ago
This reads like a disguised ad for AirGradient, which pops up here every now and then. I fell for it because it claimed to be "open". Well, although it is definitely more "open" than most, it feels like an afterthought. See for example this: https://forum.airgradient.com/t/airgradient-diy-pro-pcb-3-7-2-4-1-2023-04-13-source-code-sketch/927/13 https://forum.airgradient.com/t/airgradient-diy-pro-pcb-3-7-..., linked to a Github issue opened in June. Somehow, the source code for the new version has been overwritten by an older (CC-BY-NC) version, yet the issue has been left to rot, both on the support forum and on Github, letting me to think that the "openness" is mostly a posture to lure the HN crowd. Additionally, the -NC clause is definitely a deal breaker, and I should have investigated further before giving them my money. (it sucks to air it out in public here, but apparently the AirGradient folks don't care much about issues raised on their own forum).
- ahaucnx 3y ago
  Achim from AirGradient here. First of all, I appreciate your openness and I hope the following helps to clarify a few things: 1) All our monitor kits are licensed under CC-BY-SA (and not as mentioned above CC-BY-NC). There was a short period where we had them under NC license but since NC is not truely open-source we switched to the more permissive SA license. We wrote in more detail about this on our blog [1] 2) We are aware that our open-source firmware is currently lacking the quality level we would like to see because we have been very busy with the hardware side of the project. I do hope that in the coming months we will have more time to look after the firmware side and I already had a couple of calls with contributors in the last few days who are happy to help. It's definitely an area we need to improve. We are currently setting up a focus group and I would love to have people included that might have a more critical view on the project. Please contact me if you would be interested to participate. [1] https://www.airgradient.com/blog/thoughts-on-licensing/ https://www.airgradient.com/blog/thoughts-on-licensing/
  - loufe 3y ago
    An easy first step would be to do a minimum of engagement with those people kindly putting effort into submitting PRs to the repo. You could even assign a community maintainer to help with testing and managing PRs and issues if you don't have the time.
an_account 3y ago
I’ve gone down the air quality monitor rabbit hole and, after building my own, have settle on just buying/recommending the Awair Element.[1] Interestingly, it’s not in the table in this article. [1] https://www.getawair.com/products/element https://www.getawair.com/products/element
- newfonewhodis 3y ago
  I'm curious, what did you learn in your research? What made you land on Awair?
- ahaucnx 3y ago
  I only took sensors that have been tested by AQ-Spec into consideration because they mention the PM module used and the Awair Element was not tested by them.
- FloatArtifact 3y ago
  Cost is quite a bit higher over $200 and the components can't be replaced. This is important as there's a limited lifespan of certain sensors which should be taken into account.
  - merrywhether 3y ago
    At least for the previous model, the sensor module was an all-in-one that I was able to easily replace myself with the exact part from AliExpress. It wasn’t officially replaceable but it was fewer than 10 screws and like a 2/10 difficulty. Afterwards it booted right up.
  - mr_november 3y ago
    Currently 25% off bringing it to ~$155 so I pulled the trigger. Was going to buy the air gradient but shipping is not free and is for the awair so difference was negligible. Would also love to hear why grandparent poster has settled on recommending the awair over others.
- ahaucnx 3y ago
  Be aware that Awair has intentionally bricked their first generation of Monitors [1]. [1] https://www.reddit.com/r/Awair/comments/y7i5ku/awair_discontinues_support_for_v1_devices/ https://www.reddit.com/r/Awair/comments/y7i5ku/awair_discont...
iancmceachern 3y ago
This is common. Bluetooth headsets? There are only a handful of chipsets in all. A to D converters? Same. On and on. There are often not more than a handful of options for many ics.
bearjaws 3y ago
At the point where you spend >$400 you might as well buy hardware to purify the air... Unless you have a very specific molecule in mind, a standard HEPA + carbon filter will fix 99% of your problem.
- stephen_g 3y ago
  Usually yes. But it does depend on the air quality outside and how leaky the building is - in certain places with very poor air quality you'd need a very serious flow rate through your purifier to keep up unless you have a positive pressure system (where you filter the air coming in to the building instead of just recirculating through a filter), and keep it at a positive pressure to stop dirty air constantly leaking in (especially when running bathroom exhaust fans or kitchen rangehoods that vent outside). In fact there's an article on the very same blog as the original post about it - https://www.airgradient.com/blog/positive-pressure-systems-for-clean-air/ https://www.airgradient.com/blog/positive-pressure-systems-f... Of course the downside is larger load on air conditioning, at which point you can look at heat recovery or energy recovery ventilation systems. I'm quite keen to get one of those to get more fresh air in since I can't leave my front or most of the side windows of the house open at night (road gets too noisy in the morning).
  - FabHK 3y ago
    Exactly. It's fairly straightforward to get PM2.5 down while CO2 goes up, and vice versa. The trick is to control both.
- Retric 3y ago
  Smoke (aka fire), Humidity, and Carbon monoxide are worth monitoring and aren’t going to be fixed by a HEPA and carbon filter. Further if you’re concerned about regular air pollution it’s worth verifying how well your filtration is working.
  - aidenn0 3y ago
    Smoke is a combination of particulates and VOCs which will respectively be filtered by HEPA and carbon filters.
jiveturkey 3y ago
why do we have to keep suffering these AurGradient ads? the sensor itself is not close to being the whole story. as evidenced by the price range of the complete products built around said sensors.
- jiveturkey 3y ago
  should have said it at the same time. i'm sure i've posted this in the past. if AirGradient wishes to be taken seriously they need to get on this list: http://www.aqmd.gov/aq-spec/evaluations/criteria-pollutants/summary-pm http://www.aqmd.gov/aq-spec/evaluations/criteria-pollutants/... AFAICT https://www.aqmd.gov/aq-spec/sensors https://www.aqmd.gov/aq-spec/sensors is the same set of what they call "sensors" (but which are actually complete products), just the web page organized a little differently. Until I see an independent evaluation, AirGradient's claims are just as useless as other vendor's claims. I don't understand this bit from the AirGradient page https://www.airgradient.com/research/ https://www.airgradient.com/research/ : > Open Air will focus on PM2.5 measurements AQI is based on PM1.0, PM2.5 and PM10 measurement. Their products all (including the Open Air referenced in that page) appear to use Plantower sensors, which measure all 3 sizes.
jpambrun 3y ago
It would be nice to add radon to the table. Some consumer air quality monitor have it and the usability of the mail test means many people don't know their exposure.
quickthrowman 3y ago
Does anyone with an AQI sensor in their house actually use it to control HVAC equipment, or is it just for monitoring? In a commercial HVAC control system, if the AQI sensor (or CO2/NO2) reaches [setpoint], a make-up air unit and exhaust fan (or similar setup, could be an exhaust fan and outside air damper) will turn on until the AQI value is below the setpoint. Is anyone using an AQI sensor to energize a relay coil to turn on their furnace fan to try and correct PM2.5 and CO2 levels?
- highclass 3y ago
  In Korea, they sell complete systems that do this. Basically sensor and HVAC and/or kitchen stove fan. These systems are built in high-end new apartments.
RecycledEle 3y ago
During the pandemic I took 2 clear tubes, and put PM meters in them. I used tape to tape various COVID masks between them and to seal them kind of air tight. Then I placed computer fans at each end to push air through. I learned that the best filters I could get only worked down to 2.5 microns.
rapjr9 3y ago
I like the Dylos laser particle counter: http://dylosproducts.com/dc1100paqmc.html http://dylosproducts.com/dc1100paqmc.html The version I have has an RS-232 output and a graphing program that runs on Windows. Connect it to an old laptop with an FTDI USB to RS-232 cable and you can log particle count histories. You have to clear the air intake port of dust once in a long while with a burst of compressed air. The Sharp LED dust sensors aren't as accurate as a laser counter, but can give you a useful enough readout for dust and smoke: https://global.sharp/products/device/lineup/selection/opto/dust/index.html https://global.sharp/products/device/lineup/selection/opto/d... These are probably what is in the cheapest air quality monitors.

152 points by ahaucnx 3y ago

This is the best one I've seen: https://boseansafety.com/products/air-quality-monitor-home-t-z01 https://boseansafety.com/products/air-quality-monitor-home-t... It's by an industrial mining supply company instead of a consumer goods company, and seems to be more accurate than the cheap Amazon options I tried.

jondwillis 3y ago
Invalid SSL cert, ironic for that domain name! edit) nevermind, on public wifi
- dewey 3y ago
  Works for me on iOS Safari, maybe something on your end?
- TonyTrapp 3y ago
  No issues here with the certificate (Firefox / Windows).
- sinuhe69 3y ago
  It uses a certificate issued by Let's Encrypt, so you might need to update your root certificates list.
lysp 3y ago
This seems to look very similar to generic ali express sensors: ie. Quick search: https://www.aliexpress.com/item/1005005944910617.html https://www.aliexpress.com/item/1005005944910617.html Generally things without user manuals, or proper specifications are either directly from there, or rebadged from there.
- dahart 3y ago
  Ali express has the Bosean, and the specs appear to be different from the link you found. https://www.aliexpress.us/item/3256803168407076.html https://www.aliexpress.us/item/3256803168407076.html I see multiple knock-offs of the version you linked, the packaging looks different than the Bosean. Is the lack of a brand or company name printed on the device a potential clue about which one’s a knock-off?
pxx 3y ago
It seems unlikely it has a true CO2 sensor for that price point (it could, but the bom price of just the module is over $20). The co2 "equivalent" from VOC sensors is pretty crappy in my experience.
- bananapub 3y ago
  while true that actual CO2 sensors are expensive, this device doesn't even claim to have one
  - mikestew 3y ago
    Scroll down, and it shows a CO2 measurement on the screen.

remlov 3y ago

̶>̶ ̶̶1̶6̶9̶.̶0̶0̶ ̶t̶o̶ ̶6̶.̶0̶0̶0 ̶U̶S̶D̶.̶̶ Title was corrected. Kit costs 138.00, fully assembled costs even more.

ahaucnx 3y ago
The range is up to six thousand dollars, not six dollars.
- remlov 3y ago
  I stand corrected. The period in 6.000 in place of a comma threw me off.
LeifCarrotson 3y ago
The current edition of the "kit" is just a pre-soldered PCB, a plastic case, and some screws, it's basically a complete product. The original DIY basic or pro kit are also close to complete - basically dropping some dev boards on 0.1" headers onto the PCB (and a USB-C connector, and 1.25mm pitch PM sensor cable, slightly harder). You can also get just the bare sensor from a reputable distributor for $40: https://www.adafruit.com/product/3686 https://www.adafruit.com/product/3686 Or get the same sensor from overseas for about $12. I just built the AirGradient DIY Pro kit (no longer listed for sale on the website?), it's remarkable how PM and CO2 spike through the whole house when we cook on our natural gas stove - been waffling on that induction cooktop, but it's probably time! Still need to get the TVOC/NOx module to add to it...
- remlov 3y ago
  Looking closer, this is probably a cheaper much more feature rich alternative to the aranet4 I've got.
  - ahaucnx 3y ago
    The AirGradient also uses a SenseAir CO2 Sensor like the Aranet but also measures additionally PM and TVOCs.

ahaucnx 3y ago

Author here. I'm planning to do some more comparison testing of PM modules and planning to benchmark modules from Sensirion, Plantower, Cubic and AlphaSense. Let me know if you know some other sensor modules that could be interesting. I think this could be a pretty interesting follow up post.

agloe_dreams 3y ago
I do wonder where the VINDSTYRKA sits...though I kinda imagine that if anyone beats your price point per quality you probably wouldn't actually say.
- ahaucnx 3y ago
  The VINDSTYRKA does not contain a CO2 module which is the most expensive part of the BOM, so it's not directly comparable. For this blog post I only looked at the monitor tested by AQ-Spec [1] and the Ikea one is not in their list. [1] https://www.aqmd.gov/aq-spec/evaluations/criteria-pollutants/summary-pm https://www.aqmd.gov/aq-spec/evaluations/criteria-pollutants...
  - clairity 3y ago
    no one should worry about CO₂ at all in their homes or offices. only workers in certain industries/factories, where CO₂ can get several orders of magnitude higher, need to be concerned at all about it. you (here and in your marketing materials) are stoking needless anxiety over a gas that life on earth literally requires. pollutants, on the other hand, and particularly particulate matter (especially chemicals that we've manufactured recently in human history), do have proven negative health consequences and should be monitored and mitigated in the home and office. it's estimated that over a million people a year die prematurely of respiratory and cardiovascular complications due to pollution. in short, a lack of CO₂ monitoring in favor of PM and VOCs by ikea should be seen as a plus, not a minus here. note that VOCs are typically estimated from cheap CO₂ sensors, and are likely to be highly unreliable as a result, but more accurate (and more expensive) VOC sensing is possible, e.g., https://www.degruyter.com/document/doi/10.1515/revac-2021-0127/pdf https://www.degruyter.com/document/doi/10.1515/revac-2021-01...

emmanuel_1234 3y ago

This reads like a disguised ad for AirGradient, which pops up here every now and then. I fell for it because it claimed to be "open". Well, although it is definitely more "open" than most, it feels like an afterthought. See for example this: https://forum.airgradient.com/t/airgradient-diy-pro-pcb-3-7-2-4-1-2023-04-13-source-code-sketch/927/13 https://forum.airgradient.com/t/airgradient-diy-pro-pcb-3-7-..., linked to a Github issue opened in June. Somehow, the source code for the new version has been overwritten by an older (CC-BY-NC) version, yet the issue has been left to rot, both on the support forum and on Github, letting me to think that the "openness" is mostly a posture to lure the HN crowd. Additionally, the -NC clause is definitely a deal breaker, and I should have investigated further before giving them my money. (it sucks to air it out in public here, but apparently the AirGradient folks don't care much about issues raised on their own forum).

ahaucnx 3y ago
Achim from AirGradient here. First of all, I appreciate your openness and I hope the following helps to clarify a few things: 1) All our monitor kits are licensed under CC-BY-SA (and not as mentioned above CC-BY-NC). There was a short period where we had them under NC license but since NC is not truely open-source we switched to the more permissive SA license. We wrote in more detail about this on our blog [1] 2) We are aware that our open-source firmware is currently lacking the quality level we would like to see because we have been very busy with the hardware side of the project. I do hope that in the coming months we will have more time to look after the firmware side and I already had a couple of calls with contributors in the last few days who are happy to help. It's definitely an area we need to improve. We are currently setting up a focus group and I would love to have people included that might have a more critical view on the project. Please contact me if you would be interested to participate. [1] https://www.airgradient.com/blog/thoughts-on-licensing/ https://www.airgradient.com/blog/thoughts-on-licensing/
- loufe 3y ago
  An easy first step would be to do a minimum of engagement with those people kindly putting effort into submitting PRs to the repo. You could even assign a community maintainer to help with testing and managing PRs and issues if you don't have the time.

an_account 3y ago

I’ve gone down the air quality monitor rabbit hole and, after building my own, have settle on just buying/recommending the Awair Element.[1] Interestingly, it’s not in the table in this article. [1] https://www.getawair.com/products/element https://www.getawair.com/products/element

newfonewhodis 3y ago
I'm curious, what did you learn in your research? What made you land on Awair?
ahaucnx 3y ago
I only took sensors that have been tested by AQ-Spec into consideration because they mention the PM module used and the Awair Element was not tested by them.
FloatArtifact 3y ago
Cost is quite a bit higher over $200 and the components can't be replaced. This is important as there's a limited lifespan of certain sensors which should be taken into account.
- merrywhether 3y ago
  At least for the previous model, the sensor module was an all-in-one that I was able to easily replace myself with the exact part from AliExpress. It wasn’t officially replaceable but it was fewer than 10 screws and like a 2/10 difficulty. Afterwards it booted right up.
- mr_november 3y ago
  Currently 25% off bringing it to ~$155 so I pulled the trigger. Was going to buy the air gradient but shipping is not free and is for the awair so difference was negligible. Would also love to hear why grandparent poster has settled on recommending the awair over others.
ahaucnx 3y ago
Be aware that Awair has intentionally bricked their first generation of Monitors [1]. [1] https://www.reddit.com/r/Awair/comments/y7i5ku/awair_discontinues_support_for_v1_devices/ https://www.reddit.com/r/Awair/comments/y7i5ku/awair_discont...

iancmceachern 3y ago

This is common. Bluetooth headsets? There are only a handful of chipsets in all. A to D converters? Same. On and on. There are often not more than a handful of options for many ics.

bearjaws 3y ago

At the point where you spend >$400 you might as well buy hardware to purify the air... Unless you have a very specific molecule in mind, a standard HEPA + carbon filter will fix 99% of your problem.

stephen_g 3y ago
Usually yes. But it does depend on the air quality outside and how leaky the building is - in certain places with very poor air quality you'd need a very serious flow rate through your purifier to keep up unless you have a positive pressure system (where you filter the air coming in to the building instead of just recirculating through a filter), and keep it at a positive pressure to stop dirty air constantly leaking in (especially when running bathroom exhaust fans or kitchen rangehoods that vent outside). In fact there's an article on the very same blog as the original post about it - https://www.airgradient.com/blog/positive-pressure-systems-for-clean-air/ https://www.airgradient.com/blog/positive-pressure-systems-f... Of course the downside is larger load on air conditioning, at which point you can look at heat recovery or energy recovery ventilation systems. I'm quite keen to get one of those to get more fresh air in since I can't leave my front or most of the side windows of the house open at night (road gets too noisy in the morning).
- FabHK 3y ago
  Exactly. It's fairly straightforward to get PM2.5 down while CO2 goes up, and vice versa. The trick is to control both.
Retric 3y ago
Smoke (aka fire), Humidity, and Carbon monoxide are worth monitoring and aren’t going to be fixed by a HEPA and carbon filter. Further if you’re concerned about regular air pollution it’s worth verifying how well your filtration is working.
- aidenn0 3y ago
  Smoke is a combination of particulates and VOCs which will respectively be filtered by HEPA and carbon filters.

jiveturkey 3y ago

why do we have to keep suffering these AurGradient ads? the sensor itself is not close to being the whole story. as evidenced by the price range of the complete products built around said sensors.

jiveturkey 3y ago
should have said it at the same time. i'm sure i've posted this in the past. if AirGradient wishes to be taken seriously they need to get on this list: http://www.aqmd.gov/aq-spec/evaluations/criteria-pollutants/summary-pm http://www.aqmd.gov/aq-spec/evaluations/criteria-pollutants/... AFAICT https://www.aqmd.gov/aq-spec/sensors https://www.aqmd.gov/aq-spec/sensors is the same set of what they call "sensors" (but which are actually complete products), just the web page organized a little differently. Until I see an independent evaluation, AirGradient's claims are just as useless as other vendor's claims. I don't understand this bit from the AirGradient page https://www.airgradient.com/research/ https://www.airgradient.com/research/ : > Open Air will focus on PM2.5 measurements AQI is based on PM1.0, PM2.5 and PM10 measurement. Their products all (including the Open Air referenced in that page) appear to use Plantower sensors, which measure all 3 sizes.

jpambrun 3y ago

It would be nice to add radon to the table. Some consumer air quality monitor have it and the usability of the mail test means many people don't know their exposure.

quickthrowman 3y ago

Does anyone with an AQI sensor in their house actually use it to control HVAC equipment, or is it just for monitoring? In a commercial HVAC control system, if the AQI sensor (or CO2/NO2) reaches [setpoint], a make-up air unit and exhaust fan (or similar setup, could be an exhaust fan and outside air damper) will turn on until the AQI value is below the setpoint. Is anyone using an AQI sensor to energize a relay coil to turn on their furnace fan to try and correct PM2.5 and CO2 levels?

highclass 3y ago
In Korea, they sell complete systems that do this. Basically sensor and HVAC and/or kitchen stove fan. These systems are built in high-end new apartments.

RecycledEle 3y ago

During the pandemic I took 2 clear tubes, and put PM meters in them. I used tape to tape various COVID masks between them and to seal them kind of air tight. Then I placed computer fans at each end to push air through. I learned that the best filters I could get only worked down to 2.5 microns.

rapjr9 3y ago

I like the Dylos laser particle counter: http://dylosproducts.com/dc1100paqmc.html http://dylosproducts.com/dc1100paqmc.html The version I have has an RS-232 output and a graphing program that runs on Windows. Connect it to an old laptop with an FTDI USB to RS-232 cable and you can log particle count histories. You have to clear the air intake port of dust once in a long while with a burst of compressed air. The Sharp LED dust sensors aren't as accurate as a laser counter, but can give you a useful enough readout for dust and smoke: https://global.sharp/products/device/lineup/selection/opto/dust/index.html https://global.sharp/products/device/lineup/selection/opto/d... These are probably what is in the cheapest air quality monitors.