Disclosed herein is a portable air purifier. The portable air purifier includes: a body; first to third accommodation portions configured to have respective open top surfaces in order to separately accommodate a battery, an air compressor, and water; first to third covers configured to selectively open and close the respective open top surfaces of the first to third accommodation portions; an air inlet connected to the lower portion of the second accommodation portion, and configured to accommodate a pre-filter; a siphon pipe positioned upright inside the water of the third accommodation portion, and configured such that the top thereof is connected to the air outlet of the air compressor; a cannula installed on the top of the third accommodation portion, and configured to supply purified, humidified air to a user; and a power switch configured to control the amount of air to be supplied.

A system and method to reduce particulate pollutants in a conditioned space using an indoor HVAC unit in communication with a system controller, the system controller configured to receive at least one of an outside air particulate forecast and an access signal from a secondary source, determine at least one of whether the outside air particulate forecast is greater than or equal to a particulate limit whether an access duration value is greater than or equal to opening duration limit; and whether an access occurrence value is greater than or equal to opening occurrence limit, and to operate an indoor HVAC unit based in part on at least one of the outside air particulate forecast and the access signal.