Singapore Air Purifier Market By Filter Type (HEPA + Activated Carbon, HEPA + Activated Carbon + Pre-Filter, HEPA + Pre-Filter, Activated Carbon + Pre-Filter, Others (HEPA, Activated Carbon)), By Distribution Channel (Supermarkets/Hypermarkets, Multi-branded Stores, Exclusive Stores, Online, and Others (Direct Sales)), By End-Use (Commercial, Industrial, and Residential), By Region, By Company, Fo