Vitalight CO2 Monitor

Why should you have a CO2 monitor? Because CO2 is a good proxy for aerosols that humans exhale, and aerosols are what carry airborne diseases like COVID-19. So if you’re stuck in a box full of people, checking CO2 is a good way to tell if you should mask up or get out before you get infected. Those being the options generally under your personal control. If you’re in an environment over which you have some kind of influence, like your residence or a health-conscious business, you can use readings over 800 ppm (parts per million) as a signal to open the doors or windows or turn on the ventilation.

Gross analogy to make the point: Would you drink a beer full of some rando’s backwash? No. Well, CO2 is also a great indicator for how much of the air in your lungs came right out of someone else. Like a big communal liplock, no kidding. Neglecting masks, as most of the US does, what comes out of them goes right into you.

CO2 ppmRebreathed Fraction
How much of the air in your lungs came out of someone else

The Vitalight caught my attention because it was described as “an acceptable alternative” to the Aranet4 by the inimitable Naomi Wu, aka @RealSexyCyborg on Twitter. The Aranet4 is a rock-solid CO2 monitor that I highly recommend (and resell, so there’s your conflict of interest statement). But you’re going to pay for that quality, my friend. And if $250 is a bit much stacked against the rents you owe your phone company, ISP, streaming services, insurance companies, and every other money leech hanging off you, then a Vitalight might be a reasonable tradeoff between cost and quality.

Because everything is a tradeoff! The big tradeoff the designers of the Vitalight made was a nice bright screen that sucks electricity out of its rechargeable battery like an IT salaryman sucking down caffeine and adderall to make the code drop . Burn bright, baby, burn bright. That screen allows frequent updates, but only lasts about a day and a half, in contrast to the Aranet4’s e-ink screen that only updates once a minute, but runs for months off a couple AA batteries. And on the Vitalight you’ve got to hit the on button to see the reading, as it goes to sleep every 60 seconds to try and preserve battery life.

The other real suck with the Vitalight is that it (well, my test sample of 1 unit) typically reads about 100ppm lower than an Aranet4 (NDIR technology). I also compared it to a monitor based on a Sensirion SCD-41 (photoacoustic tech) and saw the same discrepancy. This was after following calibration steps. Part of the problem is that the Vitalight is programmed to think that it’s 400ppm out there in the big wide world. Which is currently true on top of Mauna Loa, but… not so much in cities where most of us live. My little 292K city runs about 450ppm in the hood. So the Vitalight is starting 50ppm low out of the gate. Anyway, 50-100ppm low is something to consider given 800ppm is when the CDC says you should start ventilating.


  • Cheap – $44 on Amazon
  • Small & light – 78 gm with handy clip
  • Bright, colorful display
  • Color-blind friendly (tricorder style triangle points at risk index)
  • Audible alarm at 1000ppm, easily silenced
  • Auto sleep to preserve batteries
  • USB-C charging


  • Runs ~100ppm low compared to an Aranet4 (and SCD-41)
  • Gotta keep mashing that “on” button (even if it’s plugged in)
  • Poor battery life (compared to e-ink)
  • No history
  • No Bluetooth, no app
  • Only USB-A to USB-C charging, not C-to-C
  • You’re going to be able to replace the battery when it dies.

Suggestions for The Designer:

  • $ Set your calibration point to something more typical for a user’s outdoor environment.
  • $ Leave it on if it’s got external power. Probably just a code tweak, considering you already built in a LiPo charger. Just check power on start, and don’t start the sleep timer so long as it is there.
  • $ Give us some history! A bar chart for the last couple days would be cool.
  • $$ Add a resistor to make it work with USB-C to C
  • $$ Put an inductive coil in the back shell so we can keep it topped up with a charging pad.
  • $$ Add an accelerometer so it wakes up on movement or a tap.
  • $$$ Use a better sensor. The SCD-41 is a great choice.

SBIR Phase 0 Award

Airhounds has been awarded an SBIR Phase 0 grant by Alaska’s Small Business Development Center’s TREND program. This grant will allow us to develop an SBIR (Small Business Innovation and Research) Phase 1 proposal. After discussions with Center for Disease Control (CDC) and other National Institutes of Health (NIH) staff, we are targeting the NIH Omnibus Solicitation. Our Phase 1 proposal is due 5 January 2023, so we will be spending some quality time this fall figuring out what the US government likes to see in grant proposals!

The main challenge we had writing the TREND Phase 0 proposal – which required a draft Phase 1 proposal! – was figuring out what the heck we will be doing in September of 2023. That’s a full year from when we were writing the draft. It was a good exercise, but also a reality check about the speed of government versus the speed of startups.

Anyway, wish us luck! It would be great to get some non-dilutive SBIR funding for research and development.

Oh, hey, and many thanks to the folks at Alaska’s SBDC TREND program, and to Evelyn Jacome with University of Alaska Fairbanks Center ICE program in particular, for pointing us the right direction. You all rock.

Airhounds Airborne Disease Estimator app now available for IOS

We are happy to announce that our Airborne Disease Estimator app is now available on the Apple App Store. The app connects via Bluetooth to a readily available Aranet4 CO2 monitor to measure ambient CO2, and then applies an algorithm derived from a University of Colorado Boulder model, to estimate your risk of infection by airborne disease in real time.

Point your phone at this!

The application calculates your risk of infection by airborne diseases like the common cold, chickenpox, mumps, measles, and the flu. It allows you to manually input parameters for other diseases such as COVID-19. Our next major update will allow the app to download up-to-date infectivity parameters for all active airborne diseases. (And I’ll work on getting those published so you can see them.)

Airborne Disease Estimator for IOS

Release Description:

Understand how probability of catching airborne diseases like the common cold fluctuates with CO2, physical activity, time, and more. The Airhounds Airborne Disease Estimator uses CO2 measurements and an airborne disease transmission model developed by Zhe Peng and Jose Jimenez from the University of Colorado, Boulder to estimate the probability of infection of a susceptible individual for a given airborne disease via airborne transmission. The estimator works like a calculator. You can choose which settings to adjust, and see how it impacts probability of infection!


  • Airborne disease infection probability calculator
  • Estimate infection probability for catching airborne diseases like the common cold or the flu
  • Bluetooth functionality for connecting to Aranet 4 CO2 sensors to experiment with CO2 levels in real time
  • Tweakable settings for adjusting the calculated probability: event duration, physical activity levels, masking, and more

Important Disclaimer:

The calculated probability is not a medical diagnosis, it is purely illustrative to show how airborne disease infection estimates vary with differing parameters.

The model employed only shows the probability of airborne transmission, and does not calculate probability for other routes of transmission (e.g., fomite, direct).

Furthermore, this app is not made for integrating with medical-grade CO2 sensors, and CO2 measurements should not be assumed to have medical-grade accuracy.

Always seek out a doctor for a professional opinion or diagnosis.

Limited Offer: Discount on Aranet4 Sensors & Early App Access

Interested in understanding the air quality around you and how it influences risk of catching airborne diseases? Airhounds is running a limited time offer that can help you acquire a CO2 sensor as well as get you early access to our app.

Register below to purchase an Aranet4 CO2 sensor at 20% off from Amazon’s current listing ($250 as of 5/11). That’s $200 for a CO2 sensor vs $250. The Aranet4 is a high quality CO2 sensor with a crisp E Ink display and Bluetooth capabilities:

The E Ink display ensures a long battery life; depending on the frequency at which you set the sensor to take measurements, two alkaline AA batteries can power the sensor for more than 4 years. And with Bluetooth capabilities, the sensor can be connected to our mobile app, allowing you to see how infection risk varies with indoor air quality:

Want to take advantage of this offer? Sign up using the registration form below! We’re only extending this offer to the first 10 US residents who register by 5/31!

Registration form:

Apple’s App Store Says “Nope”

Even though my cofounder Max and I did not feel ready, our gBETA Accelerator director Linda Janes and entrepreneur-in-residence Mark Lambert pushed us to get a “Minimum Viable Product” of our mobile app published. So we (well, Max really) pulled out the stops and crafted a stoplight-style app that communicates via BlueTooth with the rock-solid Aranet4 sensor, and calculates your risk of infection by COVID-19 based on peer-reviewed science from University of Colorado Boulder. Green means go, red means no. Good, solid work.

And Apple said “Nope.”

Why? Well, bottom line, because we mentioned COVID-19. They told us any app that has anything to do with COVID-19 had to come “from recognized entities such as government organizations, health-focused NGOs, companies deeply credentialed in health issues, and medical or educational institutions.” They later clarified that when they say companies deeply credentialed in health issues they mean insurance companies. (As a prostate cancer survivor, I’ve got a story about that, but must Stay On Target.)

Many thanks to Wookieepedia CC=BY-SA

Now, that seems reasonable on the face of it. You would not want a bunch Ivermectin junkies pushing COVID treatment apps, right? But when you consider that we’re in a pandemic, and large organizations typically move on the timescale of years, is it reasonable? Shouldn’t there be some sort of exception process? There probably is one, based on who you know in Cupertino, but as Credence Clearwater famously said, “I ain’t no fortunate son.”

Well, it is certainly educational. I had not really considered the gatekeeper role that organizations like Apple play. Also, from a startup perspective, Linda and Mark were 100% right to push us, because we simply had NO IDEA we would hit this kind of roadblock.

Off to think about how to move forward…