Recently, the scale for the BME680 VOC sensor readings changed on the PurpleAir map. The colors of the scale now transition from white to blue, and the levels do not have any health information associated with them. We have made this change because the BME680 sensor is still experimental, and many users were getting very concerned over the readings their sensors were reporting. We do not feel confident enough in the VOC readings yet, and we are still taking steps to understand and improve the sensors’ readings.
We are actively working on new firmware for the PurpleAir sensors that will use more memory to store variables that the BME680 sensor creates during its calibration. The sensor will then consider these variables when reporting VOC data.
For those who still want access to the scale previously used on the map, we are working on a link and will make it available for the community once it is finished. We will update this post with the link once it is released.