Abstract: An air quality control system for an HVAC system includes a particulate matter sensor for sensing particulates of outside air entering a building, a gas matter sensor for sensing a concentration level of certain types of gases present in the outside air, a fresh air damper configured to operate based on at least one of the particulate matter sensor or the gas matter sensor, and a controller communicatively coupled to the particulate matter sensor, the gas matter sensor and the fresh air damper. The controller can be configured to receive information associated with a level of particulates of the outside air from the particulate matter sensor, receive information associate with a level of concentration level of certain types of gases from the gas matter sensor, and generate a damper command to close the fresh air damper, wherein the damper command is based on at least one of the level of particulates or the level of concentration level of certain types of gases.