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Air Quality

Published on July 9th, 2016 | by Guest Contributor


Which Home Indoor Air Quality Monitors Are Best, And Why?

July 9th, 2016 by  

Originally published on Energy Smart Ohio.
By Nate Adams

We’ve all seen the studies: Our Indoor Air Quality is terrible! It’s KILLING MILLIONS!!

The problem with these studies is that if you’re like me you thought; “great, another scare tactic.” Or “it’s really only a problem in Asia.” Or of course, “Indoor Air Quality (IAQ) may be a problem in someone else’s house, but not mine.” Even if you’ve read that poor IAQ is being found to be a cause of childhood asthma and mental illness, or that air pollution is the single largest environmental health risk according to the World Health Organization, it still feels too remote to worry about it.

To further enforce the disconnect, short of a government study, there has been no clear way for the average person could gain even the vaguest insight into their indoor air quality (but here’s a hint, if you use air “fresheners,” you have an IAQ problem.)

Well, that’s all changed, no more guessing. Average Joes like you and me can now get a pretty good picture of how good or bad the air in our homes is, and test what efforts are effective at improving our indoor air quality. This is thanks to a new class of indoor air quality (IAQ) testing devices has recently hit the market in the $150-250 range.

Until now only professional level monitors for dust (PM2.5) and chemical pollution (VOCs) have been available, usually for thousands of dollars.

The new IAQ monitors create new questions. Which new air quality testers are good? Which are best? Which can help us not just understand when things are awry in our homes, but also help us make our homes healthier? Let’s pause for two definitions:

PM2.5 – Particulate matter 2.5 microns and below. It’s very small dust, or particulate matter, that we can inhale. Some of which goes straight into our bloodstreams through our lungs. For reference human hair is about 50-70 microns thick. Exhaust from cars and trucks is a major contributor.

VOCs – Volatile Organic Compounds – If you can smell a chemical, the odds are good it’s a VOC, or chemical pollutant. You can smell them because their vaporization (boiling) points are close to room temperature. Many are highly reactive with other chemicals, often creating other, even nastier ones. Some VOCs you can’t smell. Most we can’t smell at lower levels. They are most prevalent indoors where they can build up. Gasoline, cleaners, and paint are a few products that contain VOCs.

Almost a year ago I posted an article on GreenTech Media that this device revolution was coming. Shortly thereafter I set out to find answers as the monitors began to hit the market. Exciting times! Finally, it looked like there was a way to directly measure and understand the scary stories and statistics I’d heard about indoor air quality (IAQ):

– Mental illness in children has been linked to air pollution.

Children’s asthma has been causally linked to damp buildings (high humidity).

– 1 in 8 worldwide deaths is caused by air pollution. (World Health Organization)

PM2.5 is the world’s largest single environmental health risk. (WHO)

– Significant increases of respiratory and heart disease, strokes, and lung cancer. (WHO)

– Don’t go outside. Asia has air quality index (AQI) apps to predict when they can go outdoors. Buildings and cars have special filtration and keep the windows closed. (The US has an AQI website too.)

50% of Americans are exposed to unhealthy air. California, the rust belt, and the south generally have the worst Outdoor Air Quality. American Lung Association

Indoor air is 2 to 5 times as polluted as outdoor air with VOCs. (EPA)

We spend 90%+ of our time indoors. If there’s bad stuff there, it’s affecting us.

Being an expert in Home Performance (a field that studies the intersection and interconnection of insulation, HVAC, Energy Efficiency, and Indoor Air Quality), I know that indoors and outdoors are very connected, particularly in the nicer months when we open windows while outdoor pollution levels are often highest. Managing the quality of the air we breathe is a problem that needs a solution. And not just in Asia.

By mid-2015 these IAQ devices were looking like they might have the answer to the air quality testing problem, which means they may be useful for helping to reduce those ugly statistics about air pollution.

I started to beg, borrow, and… buy these devices. I first bought Foobot, Awair, NetAtmo, Hobo, and CO Experts devices. Later I was given additional Foobots and a Speck. Dylos and Air Mentor 6 in 1 were loaned to me.

After taking so much time to get to know these devices, the information they provide, and how they can be useful for improving lives I decided to put some thought into creating a framework for explaining what makes a really good consumer IAQ monitor and why.

The Energy Smart IAQ Framework

The best IAQ testers help teach you what matters and fix what matters by measuring what matters.

Good solutions require awareness, understanding, and action. Solution failure can be attributed to a weakness of awareness, understanding, or action. This is the framework I’m going to rank these devices on. Let’s briefly look at the three elements, the devices being tested, then dig into each element.

  • Awareness – What’s measured can get managed. The right sensors are needed to measure the most important air quality factors so they can be managed. It may seem obvious but it’s worth mentioning that good calibration is important. The sensors need to be fairly accurate and not prone to wild reading swings.
  • Understanding – The best IAQ testing device needs to have a good mobile and/or web app to help you build informed intuition about your specific situation. You need to see and make sense of patterns.  When do peaks and valleys occur?  What causes them? Good visualization is key, which means software reigns supreme. A good email tutorial and phone notifications are nice bonuses.
  • Action – Knowledge without action is useless. These sensors ultimately need to drive you to take actions and/or control devices that lower indoor air pollution.

The Players

I limited the review to devices that do datalogging, or measuring and recording data over time. This is a major attribute that distinguishes this new class of IAQ monitors. Without datalogging it’s difficult to understand changes over time.


Back row left to right:

Foobot – A tall white box with blue lights for good IAQ, orange for poor. Measures PM2.5, VOCs, temperature, and relative humidity.

Awair – A beautiful wood box with 5 bar charts and a numerical reading. Measures PM2.5, VOCs, carbon dioxide (CO2), temperature, and humidity.

Speck – A slightly odd shaped white box with a useful touch screen and a graph of the last hour and 24 hours. Measures PM2.5. On the webapp also temp and humidity.

NetAtMo – A thin metal cylinder, there is a smaller cylinder that is battery powered for outdoors. If you push the button on top it will light up with how good it thinks IAQ is. Measures CO2, temperature, humidity, barometric pressure, and noise in decibels (dB).

Air Mentor 6 in 1- A triangle shaped white box. Slowly flashing light indicates IAQ by color.  It measures PM10, PM2.5, VOCs, CO2, temperature, and humidity.

Dylos DC1100 Pro – A black box. It measures PM2.5 and PM0.5 (smaller particles) which are shown on the display.

Front row left to right:

Corentium Home 223 Radon Gas Detector – Measures radon. Long term, 7 day, and 1 day average. No data logging, so not part of this review.

CO Experts – Not reviewed because of single factor and no datalogging, a good low level carbon monoxide monitor.

AcuRite 00613A1 – A small black box. It measures temperature and humidity monitor – A great starter unit for about $10, but no app or datalogging, so not part of the review.

Speck – A second unit.

Hobo MX1101 – Not pictured. A very small white box. Measures temperature and humidity.

So which attributes of air pollution do we really want to detect? How do we prioritize these things if we have to sacrifice one or more? Here’s my list:

  1. PM2.5 – Research is increasingly showing this is a major villain. The recent study about increased mental illness in kids bothers me a great deal. I’m concerned about my 3 year old because I live near a busy road. It’s like smoking, it kills us slowly and causes sensitive individuals varying degrees of discomfort. The WHO said it’s our biggest single environmental health issue, so it’s top of the list. I’d love a sensor that picked up smaller particles like PM0.5 as well. Keep in mind these low cost monitors are in a different class from the high end ones used by government agencies, they are not as precise or accurate.
  2. VOCs – Volatile Organic Compounds can cause irritation of eyes, nose, and throat, headaches, nausea, as well as damage to livers, kidneys, and central nervous systems. Some are suspected carcinogens. VOCs look to be the second most important pollutant from the studies I’ve read.
  3. Temperature & Humidity – These two are usually covered with one sensor. Damp buildings are causally linked to asthma in kids, humidity and moisture are major health concerns. Contaminants can be affected by both temperature and humidity, so it’s important to have these measured to look for correlations. For example, VOCs offgas much more rapidly at higher humidity levels according to Dr. Richard Corsi of the University of Texas. Another example is that smog formation is often worst on the hottest days. Finally, mold becomes increasingly likely over 60% relative humidity, you want to understand when it happens.
  4. Carbon Monoxide (CO) – This common byproduct of combustion replaces oxygen in our blood, causing asphyxiation. Research is showing that low level carbon monoxide poisoning may cause depression, confusion and memory loss. If you have a furnace, gas water heater, gas dryer, gas range, gas fireplace, or any other appliance that burns a fuel in your home, this is something to be aware of. Standard carbon monoxide detectors do not alarm at lower levels. Being an energy auditor, I see problems with CO quite frequently. In fact, my mom was recently poisoned by older furnaces. Particularly in lower income homes, colleagues have told me they’ve seen CO problems in about 50% of homes. I would like to understand carbon monoxide concentrations in client homes over time. Unfortunately, none of the IAQ devices tested has this capability.
  5. Carbon Dioxide – CO2 is a good proxy for air freshness in a home. Outdoor levels are around 400 parts per million (ppm). Berkeley Labs found that concentrations as low as 1000 ppm affect cognitive function, and levels in the 2500 ppm range have a substantial effect on decision making abilities. Even so, this is the least important item to measure because tVOC sensors pick it up indirectly and it will likely be controlled along with other pollutants through filtration or circulation.

Would I like more? Of course! Every sensor adds cost, though, these factors are probably enough to figure out how much you should be concerned about your IAQ, and if more steps are necessary.

Sensors & Calibration

I learned through both Foobot CEO Jacques Touillon and Particles Plus CEO (a high end IAQ device manufacturer) Adam Giandomenico that there are only a few sensors of each type on the market. To my knowledge only Dylos manufacturers their own sensors in the devices I looked at. (For instance Foobot, Speck, and Awair all use the same PM2.5 sensor.) Most of these products only integrate sensors into a device, they don’t manufacture the sensors.

Since the sensors in these devices are largely the same, their effectiveness comes down to calibration.

Calibration is comparing what a sensor senses against a known quantity. For example, I grew up around very old cars (1910s-1930s) that had very inaccurate speedometers.

To calibrate them, we would take a modern car down the highway next to an old one, match their speeds at an indicated 60 MPH in the modern car, write down what the old car speedometer said, and then go back to the shop and adjust it so 60 was 60. The speedometer was now calibrated.

Calibrating these sensors is a similar process. The sensor readings are compared against a lab standard and adjusted so that the equivalent of 60 MPH is indicated on both the device and the standard. It’s done at more “speeds” than 60, of course. Done well, the sensors are calibrated before shipment and also as the sensors age using software calibration.

Foobot is the most interesting device for calibration. While it does give readings immediately after being turned on, it says it’s calibrating itself for the first 6 days and adjusting to its environment. At first I found it annoying, but after further thought the device gets more respect from me.

This leads us to our first comparison between the devices. Fair warning, I’m not a data scientist, so these are definitely anecdotal. Further complicating things is the fact each IAQ monitor has a different combination of sensors. It is difficult to truly compare apples to apples. Here’s my attempt:

Screen Shot 2016-06-15 at 3.54.23 PMResults – Awareness

The Dylos, Foobot, and NetAtMo come out on top. Dylos and NetAtMo do it primarily with novelty. Dylos is the only laser particle sensor and the only one that measures the very small and very dangerous PM0.5. NetAtMo is a weather station with both indoor and outdoor units, the only IAQ monitor with this capability. The indoor unit also measures carbon dioxide. In my mind having on-site readings of outdoor conditions (temp and humidity) helps this device hit above its weight class. Foobot slugs it out by having what I view as the best sensor array and calibration, save the very mediocre CO2 readings. The CO2 readings don’t seem to affect Foobot’s “Global Index”, or 0-100 score, so it gets a pass on this peccadillo. There are plans to update the faulty algorithm as well.

Good readings don’t mean a thing if you don’t know how to interpret them. This is where software is king. Good software accomplishes a number of things:

  • Good and Bad – A good device informs intuitively what a good or bad reading is. What are the thresholds?
  • Onboarding – Teaches you how the device and software works, preferably in small bites.
  • Good Apps – Intuitive app and/or webapp for analysis.
  • Wifi Connection – This may seem obvious, but several devices only have a BlueTooth connection. One needs a cable. This is the internet of things, people. Get your things on the internet.
  • Visual Cues – With a glance at the device you should intuitively have an idea of how your air quality is at that moment, without having to open the app.
  • Behavior – Logging and asking for tags helps you understand what behaviors are causing spikes, i.e. cooking or cleaning or rush hour traffic or high humidity.
  • In & Out – Help you understand the relationship and difference between indoor and outdoor environments. For example, when is it ok to open windows? When is it better to keep them closed and turn on the AC?
  • Trends – Helps you understand trends over days, weeks, months, and even years. Summer and winter will likely be different for IAQ, tracking over time helps you understand this.
  • Do I Need to Act? – ‘Nuff said.
  • Planning – What factors are a problem in your home so you can begin to formulate a plan to solve them.

If an air pollution detector has all of these attributes, it should be useful to homeowners (and pros) trying to diagnose Indoor Air Quality problems in their home. Done well, homeowners should have a pretty good understanding of what factors need a solution and maybe what to try first. The device may even suggest contacting a building science pro.

For pros like myself, there are a few more things that I’d like to see:

  • Advanced Visualization – An upgraded webapp that let’s me slice and dice the timeframes and readings. This is important for helping figure out what’s going on in a client home.
  • Diagnostics Usefulness – Enough well calibrated sensors to help diagnose problems rather than leave me scratching my head and looking for more data.
  • Comparing Multiple Monitors – I like to place multiple monitors in client homes, one on each floor and one outside if possible. That way I can watch for weird patterns and also splits in temperature. If the second floor is much hotter than the first in summer, there is a problem that needs to be diagnosed and solved.
  • Easy Access to Multiple Clients – I don’t want to mess around with multiple logins. Having to save and access more than one username and password for any site is a pain in the neck. I want to be able to access multiple clients with just a few clicks.

So, how do I feel the devices stack up on Software and Visualization? Here’s my comparison:

Screen Shot 2016-06-13 at 2.12.53 PMResults – Understanding

Basically, the Foobot cleans up. It simply doesn’t have a weakness in this aspect aside from no consumer desktop app. The mobile app is very powerful, it sends notifications of pollutant spikes, the simple visual cue of blue/orange lights is fabulous, the email onboarding is good, and Foobot has the only app for pros.

NetAtMo has good mobile and web apps. Mixed with the indoor and outdoor sensors, it’s a fairly useful tool for finding out if your house needs fresh air ventilation or if humidity is too high or low. (High/low humidity can cause all sorts of issues.)

The little Hobo MX1101 is the surprise here. While it only measures temperature and humidity; it’s small size, battery power, and four magnets let you put it on metal in out of the way places like an attic or inside a duct. You can then read out from it by getting close to the device with your phone using BlueTooth. The app is quite nice. It’s the underdog that has it’s day.

For more details on pros and cons of each IAQ monitor, download the free comparison PDF at the end of the article.

OK. You know there’s an Indoor Air Quality problem in your home, and you’ve been measuring with one of these devices. Now what the heck do you do? A device falls down here if it has made you aware of a problem but has no path to helping you solve it.

As Teddy Roosevelt famously said “Complaining without proposing a solution is called whining.” You don’t want a whiner, you want a solution!

A product that really helps deliver a solution to IAQ problems will have at least these attributes:

  • IFTTT Integration – If you’re a gadget freak and haven’t heard of If This Then That, check out ifttt.com. It lets you connect all sorts of different things. For example, Foobot can connect to a Wemo switch (which lets you turn a plug on and off with an app). Now when Foobot senses high pollution, it can switch on whatever device is plugged into the Wemo switch. You can also use IFTTT to connect Foobot to Google Docs and have it automatically create a spreadsheet of readings for you to analyze later. Geeky, but potentially very powerful.


  • – Thermostat Integration
    • – Turn on Furnace Fan – While spot solutions like filtration are important, many times the solution is going to be in turning on your forced air HVAC system (furnace, heat pump, and/or air conditioner) to run your home’s air through the whole house filter.
    • – Turn On Fresh Air System – Also known as mechanical ventilation systems, these bring filtered and conditioned outdoor air into your house.
    • – Turn On Humidifier/Dehumidifier – Controlling moisture levels inside the house is very important for health and comfort.
    • – Nest, Ecobee, LuxGeo Thermostats (and More) – The previous three items are only possible if an IAQ device can connect with a thermostat or other HVAC control to tell it to turn on as needed. Foobot already has integration with the LuxGeo and Nest thermostats.
  • – IoT Integration – The Internet of Things is getting to the shakeout phase. Just like VHS and BetaMax duked it out for the video market in the 80s, there are numerous competing IoT standards, such as Amazon’s Alexa. Foobot just become Alexa compliant. As winners emerge, IAQ Monitors are going to need to be able to snap into these standards and be able to control various devices within an IoT connected home. IFTTT is unlikely to be enough.

Results – Action

Only two products have the capability for action. Foobot and NetAtMo.

Foobot has several recipes on IFTTT and a connection with the LuxGeo and Nest thermostats. Through IFTTT it can control a Nest. Being familiar with this company, I know that much more is planned.

NetAtMo has its own thermostat. This is pretty good, but limiting. What if you already have a Nest, Ecobee, or other thermostat? Also, NetAtMo doesn’t measure PM2.5 or VOCs. That means it can’t turn devices on if levels of those pollutants are elevated.

Awair heavily references the capability to control other devices in their promotional video but to my knowledge has not delivered on that promise yet.

Bringing It All Together

So, when we bring together the device ratings for Awareness, Understanding, and Action, how do they score?

Screen Shot 2016-06-14 at 6.39.57 AM

Overall Winner – Awareness, Understanding and Action

Foobot has many strengths and few weaknesses. While there are areas we’d like to see improved, it simply doesn’t have a weakness large enough to get beaten by the other IAQ monitors. It’s the only one that performs really well in my Awareness > Understanding > Action framework.

Is it perfect? Heck no:

– The carbon dioxide measurements are annoying and overstated.

– There isn’t a consumer webapp (although the professional one could likely be adapted.)

– I would love to have direct outdoor temperature and humidity readings to look for correlations. (A second Foobot in a protected space like a porch can do this.) It does use regional air quality data from Breezometer.

– I would also like for it to have PM0.5 and carbon monoxide detection.

Aside from those objections, it’s head and shoulders above the competition. I plan to write a full review on it.

Runners Up

The Dylos DC1100 Pro is the only device that senses the very small particulate matter class of 0.5 microns (PM0.5). PM measurement is so crucial in Asia people check PM apps more than they check the weather. PM 0.5 are the worst of the worst, the particulates that are most likely to cause health problems because many of them go directly into your bloodstream. If measuring PM is important to you, this is the device to own. Be sure to look for the “Pro” model. The regular model only monitors PM2.5.

UX Weaknesses – This device has no wireless connections and only a PC based program for downloading and analyzing data. The PM0.5 capability at only $260 overrides my other objections. If you have a scientific bent, this is a good device to consider, although probably in addition to a Foobot rather than in place of it.

I’ve been borrowing 3 Dylos meters from my friend Linda Wigington as part of a study on low cost particulate meters called ROCIS. I plan to buy one after giving them back.

Outdoor sensors will become increasingly important. NetAtMo is the only IAQ device that has both an indoor and an outdoor sensor. Additional sensors can easily be added. The app and webapp for NetAtMo is quite good, and you can easily let others see what’s going on in your home with a few clicks. If you like weather stations and want to upgrade, try one of these.

In helping clients solve problems in their homes, I like to have an understanding of what’s going on both inside and outside their home. How quickly does heat or moisture seep in or out? When are conditions indoors uncomfortable? With NetAtMo I can work on something more than anecdotes from clients, I have hard data. The diagnosis will likely be better.


I have a lot of hope that this new class of consumer air pollution monitors can help us make our homes healthier by taking the invisible pollutants and making them visible, then letting us know if our attempts to improve IAQ were successful. The next few years will be very interesting as this market matures. In time I hope that more products will fit the Awareness > Understanding > Action framework.

Want more details on the specific devices? Download the free Pros and Cons chart of these devices. Plus you’ll get a free copy of the Indoor Air Quality chapter of The Home Performance Book when it comes out!

Reprinted with permission.


About the Author

is many, many people. We publish a number of guest posts from experts in a large variety of fields. This is our contributor account for those special people. :D

  • hybridbear

    The Foobot is 20% off today for Amazon Prime Day. This makes it cheaper than on the Foobot website. I bought one today due to the $40 savings for Prime Day.

  • JD234

    I believe the Standard Dylos ($200) actually monitors down to 1.0 microns. Like the Pro, it measures two sizes: while the Pro does 0.5 and up, and 2.5 and up, the Standard does 1.0 and up and 5 and up. So while the Standard doesn’t directly do the 2.5 benchmark, it actually does do a smaller size than most of the others here, and by all accounts is more accurate than many or most of the other monitors. So for those who don’t care about volatiles, web interfaces, etc, but just particles, the Standard seems like a fairly decent choice.

    • Nate Adams

      The big issue with Dylos is that you have to download data using a cable once a week. I did it for 3 weeks and found it annoying. Eric Wesoff at GreenTech talked recently about IoT things having a “time to kitchen drawer”. The Dylos would get there pretty fast in 99% of instances.

      I like the Foobot because even if you ignore it, it’s still logging data. If you note one day was bad, you can look back on it and try to judge what might have been the cause. Or more likely still in my professional life, I’d like to compare a really hot day to a really cold one, and maybe a moderate one. That way I can try and narrow down what is seasonal and what isn’t. The Dylos would fail that because the data would be long lost. The Awair fails it too. The NetAtMo should still have the data. That’s about it, though.

      I recently had this experience with clients who started to ignore the Foobot (it says the air is good too much, the bar needs to be higher.) They unplugged them, and I counseled them to leave them plugged in just for the data. They didn’t have AC for a bit, now they do. I can look to see what the differences are. That’s very important in diagnosis. And a big part of what these tools are good for. In fact if they fail at diagnosis, they utterly fail.

      That’s more than my 2 cents, more like $2, but there you go…

      • JD234

        Yeah, the “time to kitchen drawer” is my problem with all of these things. I’m much more interested in a few measurements — various rooms, possibly outside, perhaps with and without air filters running — than in dense time-varying data, which I don’t expect to be very interesting, since my home situation doesn’t change much and if I care, it will probably track the public data for my city that I can obtain elsewhere. I’d be much more interested in a unit I could rent or borrow for a day than forking over the full purchase price, but I imagine the price of having someone come out to test things is probably close to the purchase price, so there’s really no cheap one-day option.

        • Nate Adams

          Yup. I used to have an Air Advice. It was $2000 for the device, and $700/year to have it. It’s now $2500/$1000. I had to make two trips – drop off and pick up. At $200/test I lost money, but couldn’t charge any more than that. So I stopped doing it. Foobot seems to be 80% as good for the same price I charged, plus it’s there forever. I much prefer a movie to a picture, and having it there for good vs. 4-7 days is a big deal. I believe IAQ will vary substantially seasonally, and this is how to figure that out.

          Plus I routinely have comfort complaints from clients about different floors being different temps, I can deploy 3-4 per house and track with data, not anecdotes.

          If it’s worth $200 to solve your problem, pop on one. I think it’s plain Foobot is the horse I’m backing. If it’s not worth $200, try and push it back in your mind, don’t worry about it.

  • Charlotte Omoto

    What about direct air cleaner like the Dyson Pure Cool? It claims to filter out particulates down to 0.3 microns, and monitor air quality and filter quality. I got it because we don’t have A/C and open the windows at night to cool, but last summer with all the wild fires, the outdoor air quality was terrible!

    • Nate Adams

      Good question, there are so many devices, filters, etc. that it’s tough to know what to try. My focus is on the monitors.

      How do YOU feel the Dyson works? What do you like/dislike?

      • Charlotte Omoto

        I like it because you can put it on auto mode so it monitors air quality and turns on higher if the quality is not good. In addition to particulates it cleans VOC with carbon filter. Then you can see the change in quality on a mobile app.

        • Nate Adams

          I wish there was a device like that for the whole home using the duct system. Alas, not yet.

  • vensonata .

    The Tesla model x air filter is an interesting innovation for cars. Why not for houses? A nice little side business for Tesla…ultimate air purification systems.

    Personally we use large numbers of indoor house plants for filtration. Recommended by NASA when they were researching the limited atmospheres of space capsules, they realized the amazing capacities of certain plants for absorption of toxins.

    • Nate Adams

      The major benefit of cars is that they are airtight. A Tesla recently swam through a Russian tunnel proving this…

      Homes all leak in varying degrees and from varying places. While filtration is immensely helpful, it’s often not enough to solve IAQ problems. The house needs to be made more airtight before control can be taken over the indoor environment, otherwise dust and air tend to sneak in.

      Diagnosing and solving those problems is my day job, which is why I had so much interest in these devices, I see them being an onramp to Home Performance.

      It would be interesting to actually measure if plants help with VOCs in a measureable way. I’d probably lean towards an activated carbon filter or something along those lines, but I’m curious. If you get a Foobot or other monitor, please share!

      • vensonata .

        Foobot is coming. I am interested in air quality as well. We live in a pristine forest far from any city. The outdoor air is pure. However we need to control air flow in the house because it is cold climate, high elevation (4200 ft) and we are off grid with solar. So energy for heat recovery ventilator doesn’t work. Therefore, one way ventilation is used, but one must be moderate or lose the benefits of super insulation. We have monitored for radon and found only traces, I don’t expect to find much problem with carbon dioxide build up, and we have been careful about paints etc. even having a kitchen that is sealed from the rest of the house for venting of Propane cooking off gases. When I say “plants” I am talking about 80 large plants, so I look forward to “real science” air monitoring.

        • Nate Adams

          Be sure to let us know what you find! I’ll be writing more about using Foobot in my practice. It’s been very interesting.

  • Freddy D

    Co2 is an excellent mechanism to detect an overly-tight sealed home/ building. There are thousands of potential toxins that these don’t measure but sufficient ventilation is the answer. With better building codes this will become more of an issue with tighter buildings. They are supposed to have active, controlled ventilation, but then it needs to be monitored to ensure its working. And there are very high correlations of asthma and other allergies with too little exposure to outdoor environments while growing up – too clean causes more health problems than it solves. On the other hand, sounds like in super polluted places there is no good answer.

    • TedKidd

      “sufficient ventilation is the answer.”

      Is it “the” answer?

      “in super polluted places there is no good answer.”

      Not sure how to say this without hurting your feelings, so I’ll just say it. This prescriptive simplistic thinking does a really great job of illustrating how poor critical thinking/lazy thinking are a real problem.

      Instead of jumping to the quickest and easiest conclusions, we need to encourage people to think more deeply. These devices allow us to move away from “everybody should do this” thinking that allows people to feel they solved “the problem” when often they’ve made it worse. We need to move towards a more proactive approach, one that CONFIRMS improvement, and that requires raising the bar on our thought processes.

      When measurement was unaffordable for most, we had little choice but to provide prescriptive answers. But do we really want quick answers now that we can begin to get GOOD answers?

      With these devices we can measure, adjust… measure, adjust… And that’s the path to improvement.

      • Freddy D

        True enough – perhaps I should have clarified that these things may provide marginal use at best and the objectives do indeed differ based on the outdoor air situation. That said, my point is that real biochemistry is thousands of times more complicated than a handful of attributes. To aim for low voc or pm2.5 when a thousand other attributes are in bad shape simply gives a false sense of security. Most people are better off opening a window based on co2 measurement and those that live in super polluted places like Chinese cities will have serious difficulties really fixing their indoor air.

  • Ivor O’Connor

    Any of the authors actually use these devices and have something good to say about them?

    • Nate Adams

      I’m the author, and yes! Foobot is the only one that ran my gauntlet. NetAtMo and Dylos 1100 Pro also had a lot of pros vs. cons.

      • Ivor O’Connor

        I meant more along the lines of the normal authors that write most of the articles on CT. It being a new subject for me I’m looking for people who also may feel that it might not be needed and what they think once they’ve tried them.

        • Ah. No, don’t think any of us have tried these.

          • Ivor O’Connor

            Ahh, ok. Being a new subject I’ll keep my eyes open and this article for reference.

        • Nate Adams

          It’s a new subject to everyone, really. These devices have only hit the market in the last few months, my article is the first I’ve seen to review them technically (albeit imperfectly.) I’m friends with a number of the researchers in the IAQ field, it’s small enough that’s still possible, which gives you an idea of how mature it is…

          I’m very curious to see what other authors think, too. That brings up another problem, though:

          The real curse of these devices is that once you get the info, what do you do with it? What should you worry about? What shouldn’t you worry about? And how do you solve the problems they might find?

          Very few people have the holistic understanding of how buildings work to be able to have a high likelihood of solving the problems uncovered. A filter or a humidifier may only mask a more substantial problem. It’s the opinions of folks like me I’m most interested in because they have the deeper understanding of building performance.

          • nakedChimp

            Not just that.. but how accurate are those devices and how stable is the calibration?
            I work in micro climate research as a technician and (for example) we have devices that cost $2500 a piece that only measure CO2 and H2O.. they drift at least 100ppm over 6 months and each of them into another direction.
            Then there are the workhorses of devices that measure the same stuff.. need calibration every 6 months with special gases (that them self have been certified = expensive), drift maybe 5ppm (due to water vapor making it past the seals over time) but cost at least 6 times as much.

            So yeah, find out about absolute errors of these units, drifts, calibration needs etc., as otherwise they won’t tell you much for a lot of money.

          • Nate Adams

            It’s important not to make these devices something they aren’t. They really aren’t measurement devices, they’re trending devices. Fitbits are only +/- 20% accurate yet over large data sets they’re very useful.

            The VOC sensors are supposed to be pretty stable in the Foobot, from what I understand, they were developed for BMW to test chemicals in the cabin. Foobot at least attempts to adjust the sensors for drift over time. tVOC sensors are a bit limited, though, because they pick up darn near everything, but don’t tell you what it is. It could be CO, or CO2, or chemicals. Who knows?

            Regardless, these are far better than what we had before, which is nothing. I had an Air Advice. It was expensive to buy and to continue to use, plus you have to drop it off and pick it up. Now one inexpensive device can give you some insight into what’s happening in a home. If you see problems, you can deploy a higher level device.

  • S Herb

    I would like to see some inexpensive portable Outdoor monitors with good smartphone integration, for PM2.5, NOX, and other dieselly things. I am always amazed how few people on the street seem to be bothered by the air, and having dozens of ‘amateurs’ out on the streets taking real world readings every day and publishing results on the web could result in some consciousness raising. I don’t know much about the technical requirements for the devices but this article gives me hope that they are becoming practical. The outdoors monitors need not be as sensitive, since they will be dealing with higher peak levels, and accuracy is less of an issue compared to what environmental agencies need.

    • Bob_Wallace

      There are air quality sensors that interface with smart phones and computers.

      • Lillian8541

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    • Nate Adams

      I have a Foobot on my back porch where it’s protected from precipitation. I also have the outdoor sensor of my NetAtMo. A Dylos lived there while I was borrowing it. These devices are adequate for that purpose.

    • hybridbear

      Me too! I’d like one I can use both indoors & outdoors. I live within a rectangle of three major freeways & a heavily trafficked 6-lane busy street. The busy street is a half block away & the farthest freeway is under 0.5 miles away. Everything is extremely dusty at my apartment because of all the pollution. I’ve been getting the daily AQI & Ozone levels from the MN PCA for about a year now, but I’d like to get my own monitor so I can see how the level in my neighborhood & inside my apartment compares to the average calculated for all of the Twin Cities by the MN PCA.

      Any recommendations for that? Would any of these units work outdoors too? Not to be mounted permanently outdoors, but to be used outdoors in the short term?

      Of the units in this article, I’d be inclined to get the Awair, because I have another portable thermometer with a RH sensor that seems to work pretty well. I bought a few of them on Amazon over the years & I have one in my liviing room, on my desk at work & in the basement at my parents’ house. So I wouldn’t need to rely on the Awair’s inaccurate RH output.

      Any suggestions @nate_adams_eshp:disqus? Thanks for writing this article!

    • Nate Adams

      Oh, there is a product called Tzoa that is supposed to be a wearable and measures PM2.5. Like many of these devices, it seems to be stuck in development, I’m not sure when it will hit the market. It looks a bit like the communication badges in Star Trek.

      • S Herb

        Interesting. From my recent reading on NOX detection, that will be much tougher.

        • Nate Adams

          You’re ahead of me on NOX, I haven’t looked into it at all. Like I said in the article, I’d love more than my little list, but very soon the devices climb over $200. $200 has been found to be the upper limit of “impulse” buys. If these come down under $100 I think there will be a lot more adoption too, but that also precludes more sensors, most likely.

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