CO2 PPM READINGS ON A LED DISPLAY Assess the quality of your air and help keep air fresh in any indoor space with this CO2 meter with a highly readable 2.8" 320 x 240 resolution LED screen display. SAFETY FOR EVERYONE Monitor public and private spaces for excess CO2 levels caused by large groups of people in an enclosed area exhaling CO2. CO2 or carbon dioxide serves as an accurate surrogate measure of risk for indoor transmissibility of airborne pathogens. As the number of people increases or ventilation decreases, CO2 levels will rise. Increase ventilation with outdoor air to reduce CO2 levels and risk of viral transmission within your indoor spaces. MULTI-MEASUREMENTS In addition, check temperature and humidity levels while reading accompanying CO2 levels.HEALTHY AIR & HEALTHY PEOPLE Monitor and maintain adequate ventilation levels by opening windows to draw outdoor air and reduce CO2 levels to 450-500 ppm or less. Studies have shown air ventilation is more effective than even mask-wearing in reducing the transmissibility of any airborne pathogens. Note: Due to the light and screen setting difference, the item's color may be slightly different from the pictures. Please allow slight dimension difference due to different manual measurement. Sold by-YJL official store