For a couple hundred bucks you can get a highly accurate CO2 sensor that reads out via a USB-serial connection: https://www.co2meter.com/products/k-30-co2-senso

For a couple hundred bucks you can get a highly accurate CO2 sensor that reads out via a USB-serial connection: https://www.co2meter.com/products/k-30-co2-sensor-module https://www.co2meter.com/products/k-30-co2-sensor-module