A system includes a concentration sensor, a flow sensor, and a controller. The concentration sensor is configured to measure a concentration of a contaminant in a cabin of an aircraft. The flow sensor is configured to measure a flow rate of air into the cabin. The controller is configured to determine whether a concentration measurement of the contaminant in the cabin exceeds a first concentration threshold. The controller is configured to, in response to determining that the concentration measurement does not exceed the first concentration threshold, control the flow rate of air into the cabin based on a flow rate setpoint. The controller is configured to, in response to determining that the concentration measurement exceeds the first concentration threshold, control the flow rate of air into the cabin based on a flow rate setpoint and a correction factor that is based on a flow sensor tolerance.