What is the recommended air quality standard for CO2 levels in occupied spaces?

The recommended air quality standard for CO2 levels in occupied spaces is below 1,000 ppm (parts per million). This level is considered acceptable because it helps to ensure adequate indoor air quality and maintain the comfort and health of occupants. At concentrations above 1,000 ppm, it is common to experience increased respiratory discomfort, a decrease in cognitive function, and potential headaches, which can affect productivity and overall well-being.

Maintaining CO2 levels below this threshold is crucial in environments such as offices, schools, and other public spaces, where a significant number of people gather and share the air. This standard aligns with guidelines from organizations like ASHRAE (the American Society of Heating, Refrigerating and Air-Conditioning Engineers) and the U.S. Green Building Council, emphasizing the importance of proper ventilation and air exchange in maintaining healthy indoor environments.