Variables
Description
What is this formula?
This formula estimates the steady-state indoor concentration of a pollutant based on outdoor concentration, indoor generation sources, and ventilation rate.
When to use it
Use it to evaluate indoor air quality in buildings where pollutants are generated by occupants, equipment, industrial processes, cleaning products, combustion devices, or laboratory activities.
Example
Data:
Cout = 20 µg/m³
G = 5000 µg/h
Q = 250 m³/h
Formula:
Cin = Cout + G/Q
Substitution:
Cin = 20 + (5000/250)
Cin = 20 + 20
Result:
Cin = 40 µg/m³
Applications
Indoor air quality studies, HVAC design, building ventilation analysis, contaminant control, industrial hygiene, green buildings, schools, hospitals, laboratories, and office environments.
Note
This is a simplified steady-state mass balance model that assumes complete mixing of air within the indoor space. Real buildings may exhibit concentration gradients, varying ventilation rates, pollutant deposition, filtration effects, and transient conditions that require more advanced models.