Airmega 450

So you prefaced 1,400 square feet as "Room Volume". I assume this is still square feet and not 1,400 cubic feet, the latter actually being volume. Purifiers aren't good at removing visible dust particles as they're large and heavy. See the sticky post at the top of the subreddit and our FAQs wiki pa

Going by the AHAM 2/3 rule, your 15' x 15' x 10' bedroom needs minimum Clean Air Delivery Rates (CADRs) of 188 CFM. The Coway Airmega 250S can achieve that, although I don't know if you have allergies, high pollution levels, or other circumstances that need increased CADRs. The Coway Airmega 450 doe

I assume you're an expatriate living in the US? Most Americans don't use "whilst". 😉 Unfortunately if you have high levels of particulates (pollen, dust, mold, etc.) and gases/vapors/odors (including VOCs), you generally need two types of air purifier. This is because particulates-focused purifiers

I assume the 500 sq. ft. you mentioned in another comment is an open space without walls. (You need a purifier for each room, as they can't overcome walls and doors.) If the 500 sq. ft. is open, you would need a minimum of 334 CFM CADRs. These figures are for normal pollution levels. You may have el