Given that this image: https://cdn.prod.website-files.com/653a9fbd1075088b6c8f8bd3/67c7121d68e04574ca5ef326_Step_02_003.png https://cdn.prod.website-files.com/6

Given that this image: https://cdn.prod.website-files.com/653a9fbd1075088b6c8f8bd3/67c7121d68e04574ca5ef326_Step_02_003.png https://cdn.prod.website-files.com/653a9fbd1075088b6c8f8bd3/... shows PM2.5 and CO2(ppm) it may imply they monitor particles and CO2 levels. My guess is it also monitors humidity, and temperature. Humidity helps distinguish smoke from water vapor (eg. steaming shower). CO2 sensors are generally pretty accurate, but PM2.5 sensors are notoriously prone to false spikes usually caused by dust in or around the sensor: https://www.reddit.com/r/Awair/comments/10r1uyo/inaccurate_pm25/ https://www.reddit.com/r/Awair/comments/10r1uyo/inaccurate_p... or https://forum.airgradient.com/t/unusual-pm2-5-readings-on-new-indoor-sensor/2416 https://forum.airgradient.com/t/unusual-pm2-5-readings-on-ne... or https://community.purpleair.com/t/what-to-do-about-incorrect-readings/645 https://community.purpleair.com/t/what-to-do-about-incorrect... My guess is it's likely a sensor in a hotel room accumulates dust over time, leading to high PM2.5 measurements maybe when something (eg. suitcase) bumps against the case, shaking the accumulated dust and releasing it around the sensor.