Have you gone nose blind to household odors?Check multiple measures of your home's air quality. This air quality monitor has a fan onboard that allows REAL-TIME accurate monitoring of formaldehyde (HCHO), total volatile organic compounds (VOCs), and <2.5 micron-sized fine particulate dust (PM2.5). Formaldehyde is an environmental carcinogen yet odorless at lower concentrations that can off-gas from various building materials. Detect low levels of airborne organic compound and odors or VOCs emitted from biologic and synthetic sources such as plastics not perceivable to the human nose. Check microscopic inhalable dust levels with PM2.5 levels.Problems with allergies?See when you may need to change your home?s air filter. Watch the levels of formaldehyde and VOCs drop when the windows are opened. Learn where air quality is poorer and where your allergies can worsen. Allergies that are difficult to control with unexplained coughing, runny nose, and shortness of breath may indicate sick building syndrome.Tips on Use:-PM2.5 reads in ?g/m³, not AQI; search AirNow AQI calculator online for conversion.-Large variations or 9.999 TVOC readings do not indicate an error as this instrument is a sensitive electronic nose; environmental TVOCs vary much and high TVOCs often can result from interference from benign fragrances or odors.-Calibrate if 0.000 indoor readings noted or with new device.Specifications:-2.8? 240 x 320 LCD-2200 mAh Li battery; DC 5V micro USB charging-HCHO Range: 0 - 1.999 mg/m3-TVOC Range: 0 - 9.999 mg/m3-PM2.5 range: 0 - 999 ?g/m3; PM10 calculated from measured PM2.5-Adjustable alarm for various HCHO levels and auto-shutoff timing (up to 2 days).As the onlyUS based retailer of this item, we have a chemist on staff to answer any technical questions. We also email our 20+ pgs eBook on Gas & Air Quality Hazards after delivery.