![Amazon.com: SAF Aranet4 Home: monitor inalámbrico de calidad del aire para interiores, para el hogar, la oficina o la escuela (CO2, temperatura, humedad y más), portátil, alimentado por batería, pantalla de tinta Amazon.com: SAF Aranet4 Home: monitor inalámbrico de calidad del aire para interiores, para el hogar, la oficina o la escuela (CO2, temperatura, humedad y más), portátil, alimentado por batería, pantalla de tinta](https://m.media-amazon.com/images/I/51NzIhvRNDL._AC_UF894,1000_QL80_.jpg)
Amazon.com: SAF Aranet4 Home: monitor inalámbrico de calidad del aire para interiores, para el hogar, la oficina o la escuela (CO2, temperatura, humedad y más), portátil, alimentado por batería, pantalla de tinta
![What would be the first thing to do if Aranet4 device shows CO2 levels well above 500 ppm in fresh air outdoor environment? What would be the first thing to do if Aranet4 device shows CO2 levels well above 500 ppm in fresh air outdoor environment?](https://forum.aranet.com/site/assets/files/1729/calibration.1052x0-is.png)
What would be the first thing to do if Aranet4 device shows CO2 levels well above 500 ppm in fresh air outdoor environment?
![Aranet4 device shows incorrect and enlarged CO2 measurements in high altitude locations with lower atmospheric pressure. How so? Aranet4 device shows incorrect and enlarged CO2 measurements in high altitude locations with lower atmospheric pressure. How so?](https://forum.aranet.com/site/assets/files/1649/manual_cal.png)
Aranet4 device shows incorrect and enlarged CO2 measurements in high altitude locations with lower atmospheric pressure. How so?
![David Elfstrom on Twitter: "Note for #covidco2 measurements using ARANET4: The calibration procedure note in the app states it is to 400 ppm but on the unit it is to 420 ppm, David Elfstrom on Twitter: "Note for #covidco2 measurements using ARANET4: The calibration procedure note in the app states it is to 400 ppm but on the unit it is to 420 ppm,](https://pbs.twimg.com/media/E3sKRN3XoAo8L0F.jpg)
David Elfstrom on Twitter: "Note for #covidco2 measurements using ARANET4: The calibration procedure note in the app states it is to 400 ppm but on the unit it is to 420 ppm,
![Aranet on Twitter: "😱 Can outdoor air CO2 reading ever exceed 450ppm? A reading as high as this one is unlikely, so it's important to calibrate your Aranet4 device every once in Aranet on Twitter: "😱 Can outdoor air CO2 reading ever exceed 450ppm? A reading as high as this one is unlikely, so it's important to calibrate your Aranet4 device every once in](https://pbs.twimg.com/media/EJLR6FSWkAACE4q.jpg:large)