Found a bargain CO₂ meter worth having for virus defense

As I’ve blogged before, ventilation is one of the most important defenses against air that might be contaminated with coronavirus or anything else, and a CO₂ monitor is a good way to check it, wherever you are. I’ve bought several models and have taken them with me into stores, restaurants, gyms, doctors’ offices. (Yes, doctors; all the ophthalmologists I’ve visited have bad ventilation, except at Lahey Health. Pharmacies, and doctors’ offices in hospitals, have all been decent, I’m happy to say!)

For my use I’ve settled on a $249 model, the Aranet4 (at right in the photo). But it’s expensive, and I recently discovered a budget alternative that has some compromises but strikes me as a darn good bargain, at $79. Here are some quick notes for comparison.

• Aranet4, $249:
  • Pro: Pocket size – 4 oz, less than 5 cubic inches. Doesn’t need to be charged (runs months on 2 AA). Bluetooth and app allow logging readings over time and setting various configuration options; good instructions.
  • Con: pricey; only updates every 1-5 minutes; no on/off switch!
• Jicfung, $79:
  • Pro: Cheap; good, bright, readable display; updates continuously.
  • Con: Too big for most pockets (about 15 cubic inches), 5.2 oz; only displays temp in Centigrade; must be charged daily; no log of recent readings; instructions are in “Chinglish”; cannot be calibrated!

A few notes:

• The first Jicfung I received would not take a charge. I returned it; the replacement works fine.
• I first learned about the Aranet4 from friend Miguel Tovar in a comment on the January post below, but it wasn’t yet available in the US. Then advocate Grace Cordovano showed up with one at a conference in Boston, and I immediately bought it.
• Precision: someone always asks why the readings on my various units are different. These are not lab-quality scientific instruments – not at this price! But the readings from all the units I’ve tried have tracked up and down together, and that’s good enough to tell whether there’s reasonably good ventilation where I am. (You want it to be under 1000.)

---

Previous posts on ventilation and CO₂:

• 9/20/20: Winter’s coming. Time to talk about ventilation for coronavirus defense. Doesn’t mention CO₂ but explains why ventilation and fresh air are important for virus defense.
• 1/23/21: Ventilation for COVID-19 defense, part 2: CO₂ and new warnings. Lots of good educational material from news sources as we tried to figure out how to make it through the winter, before vaccines arrived.
• 2/15/21: Update on CO₂ monitoring for virus protection. Readings I’d recently taken at local places.
• 2/16/21: “A realist adjusts the sails”: my CO₂ monitor, levels at my Y, Osterholm’s podcast, B117. More readings, and info on the unit I bought back then, which is apparently no longer available.