Global Air Purifier Market Assessment, By Installation [Fixed/In-duct, Portable/Standalone], By Technology [HEPA, Ionic, Activated Carbon, Photocatalytic, Ultraviolet, Electrostatic Precipitators, Other], By Coverage [Below 250 sq feet, 250 to 500 sq feet, Above 500 sq feet], By End-user [Residential, Commercial, Industrial], By Price Range [Mass Segment, Premium Segment], By Distribution Channel [Offline, Online], By Region, Opportunities and Forecast, 2017-2031F