PROBLEM TO BE SOLVED: To reduce running cost by always maintaining high removal performance of water-soluble components in air, improving maintainability, and reducing running cost. SOLUTION: The present invention comprises a pre-stage air washer 11 that uses a chemical solution containing at least one of an alkaline solution and an acidic solution as an absorption solution, a chemical solution supply device 12 that supplies the chemical solution to the pre-stage air washer 11, and a pre-stage air washer. At least one of a rear-stage air washer 13 that is arranged on the downstream side in the air flow direction of 11 and uses pure water as an absorption solution, and a cation exchange resin and an anion exchange resin through which the absorption solution of the rear-stage air washer 13 passes. From the chemical solution supply device 12 by estimating the concentration of the pollutant contained in the air flowing into the air washer 11 in the previous stage based on the conductivity of the ion exchange resin 14 and the absorbing solution that has passed through the ion exchange resin 14. It is characterized by including a control unit 16 for calculating the amount of a chemical solution supplied to the air washer 11 in the previous stage. [Selection diagram] Fig. 1【課題】空気中の水溶性成分の除去性能を常に高く維持すると共にメンテナンス性の向上を図り、ランニングコストの削減を図る。【解決手段】 本発明は、アルカリ性溶液と酸性溶液の少なくともいずれかの溶液を含む薬液を吸収液とする前段のエアワッシャ１１と、前段のエアワッシャ１１に薬液を供給する薬液供給装置１２と、前段のエアワッシャ１１の空気流通方向の下流側に配置され、純水を吸収液とする後段のエアワッシャ１３と、後段のエアワッシャ１３の吸収液が通過する陽イオン交換樹脂と陰イオン交換樹脂の少なくともいずれかのイオン交換樹脂１４と、イオン交換樹脂１４を通過した吸収液の導電率に基づき、前段のエアワッシャ１１に流入する空気中に含まれる汚染物質の濃度を推定することで、薬液供給装置１２から前段のエアワッシャ１１に供給する薬液の量を演算する制御ユニット１６と、を備えていることを特徴とする。【選択図】図１
