Fig. 2
From: Building an indoor air quality monitoring system based on the architecture of the Internet of Things
Effects of CO2 concentration on the human body. The indoor CO2 concentration ranging from 350 to 450Â ppm is good, and at a concentration higher than 1000Â ppm, people begin to experience symptoms, such as drowsiness, and such higher concentration leads to severe symptoms. Hence, ASHRAE suggests that the indoor CO2 concentration should not be higher than 1000Â ppm