Consumer Reports: How to monitor air quality - YouTube
AirVisual Series Air Quality Monitors | IQAir
Indoor Air Quality Monitor IGERESS Air Pollution Detector Meter for Real-time Detect Formaldehyde(HCHO) TVOC PM2.5 Accurately and the Color LCD Screen Intelligent Air Quality Detector has Multi-functions Operating System and Time Display :
Air Quality Monitor IGERESS 7 in 1 Indoor Air Pollution Detector Meter for Formaldehyde, VOC, PM2.5, PM1.0, PM10, Temperature and Humidity Test, Real Time Air Tester Kit with Colorful LCD Screen :