Inside an HVAC and duct system.

Monitoring of CO2 is one way to demonstrate if school space has adequate ventilation according to the recommended rate. While it is not a direct measurement of outdoor air ventilation rate such as from a testing, adjusting, and balancing (TAB) test, CO2 can be monitored continuously to determine if ventilation is sufficient for the number of occupants and their activity levels. Logging of the measured CO2 concentrations throughout each day, and over time, enables facility staff to identify and fix ventilation problems in classrooms. 

In areas faced with poor outdoor air quality including episodic events such as wildfire smoke, monitoring of fine particulate matter (PM) is very valuable in addition to CO2 monitoring. Consumer grade IAQ monitors are increasingly common, with many that can measure both CO2 and PM at reasonable accuracy that can help inform building operation and maintenance. Long-term PM data is useful for documenting the benefits from improved filtration, for example. 

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