An environmental control system to remove contaminants in supply air that flows into an environment, comprising: a outside air contaminant sensor that senses contaminants in outside air that is a part of the contaminants in supply air; a recirculated air contaminant sensor that senses contaminants in recirculated air that is another part of the contaminants in supply air, wherein the recirculated air is supplied by the environment, a pressure sensor that senses pressure of the supply air in the environment, a temperature sensor that senses temperature of the supply air in the environment, a carbon dioxide sensor that senses carbon dioxide in the recirculated air exiting the environment, a controller; wherein the outside air is supplied through engine or APU bleeds or other air sources including ground supplies and electric compressors, or recirculating air in the ECS; wherein the outside air contaminant sensor is upstream of the environment; wherein the recirculated air contaminant sensor is downstream of the environment; wherein the pressure sensor is located in the environment; wherein the temperature sensor is located in the environment; wherein the carbon dioxide sensor is downstream of the environment; and wherein the controller is in continuous communication with the outside air contaminant sensor, the recirculated air contaminant sensor, the pressure sensor, the temperature sensor, and the carbon dioxide sensor; wherein, upon receipt of a threshold signal from one of the sensors, the controller controls an inflow of the outside air supplied through the source outside of the ECS that mixes with the recirculated air (21; the ECS being characterized in that: the controller is configured to compare contamination signals to a contaminant concentration look up table that has data of contaminant concentration equivalents versus population percentile of a sample database. a outside air contaminant sensor that senses contaminants in outside air that is a part of the contaminants in supply air; a recirculated air contaminant sensor that senses contaminants in recirculated air that is another part of the contaminants in supply air, wherein the recirculated air is supplied by the environment, a pressure sensor that senses pressure of the supply air in the environment, a temperature sensor that senses temperature of the supply air in the environment, a carbon dioxide sensor that senses carbon dioxide in the recirculated air exiting the environment, a controller; wherein the outside air is supplied through engine or APU bleeds or other air sources including ground supplies and electric compressors, or recirculating air in the ECS; wherein the outside air contaminant sensor is upstream of the environment; wherein the recirculated air contaminant sensor is downstream of the environment; wherein the pressure sensor is located in the environment; wherein the temperature sensor is located in the environment; wherein the carbon dioxide sensor is downstream of the environment; and wherein the controller is in continuous communication with the outside air contaminant sensor, the recirculated air contaminant sensor, the pressure sensor, the temperature sensor, and the carbon dioxide sensor; wherein, upon receipt of a threshold signal from one of the sensors, the controller controls an inflow of the outside air supplied through the source outside of the ECS that mixes with the recirculated air (21; wherein the outside air is supplied through engine or APU bleeds or other air sources including ground supplies and electric compressors, or recirculating air in the ECS; wherein the outside air contaminant sensor is upstream of the environment; wherein the recirculated air contaminant sensor is downstream of the environment; wherein the pressure sensor is located in the environment; wherein the temperature sensor is located in the environment; wherein the carbon dioxide sensor is downstream of the environment; and wherein the controller is in continuous communication with the outside air contaminant sensor, the recirculated air contaminant sensor, the pressure sensor, the temperature sensor, and the carbon dioxide sensor; wherein, upon receipt of a threshold signal from one of the sensors, the controller controls an inflow of the outside air supplied through the source outside of the ECS that mixes with the recirculated air (21; the ECS being characterized in that: the controller is configured to compare contamination signals to a contaminant concentration look up table that has data of contaminant concentration equivalents versus population percentile of a sample database.