Abstract: An apparatus for continuously supplying air into an indoor space is disclosed. The apparatus includes a sunlight collector for activating carbon dioxide contained in the air by irradiating sunlights thereto, a reservoir for storing and discharging the activated carbon dioxide, the reservoir holding a reaction solution capable of exchange reaction with the carbon dioxide and a unit for reducing the carbon dioxide concentration in the air to a level non-hazardous to a human body. The apparatus may further include an infrared radiation lamp that can produce infrared rays to maintain the electric conductivity of the reaction solution within a preselected range at night or under bad weather conditions. A method is provided whereby atmospheric air passes through the reservior to undergo exchange reactions with the reaction solution. The method produces atmospheric air containing carbon dioxide molecules in a higher energy state, and directs the air toward the indoor space.