A single air purifier can only filter the air in the space it's standing in. It cannot pull allergens from the bedroom down the hallway, even if that hallway is open.

That's the practical reason most allergy sufferers don't get the relief they expected from their first purifier: they bought one unit, placed it in the living room, and assumed it would help with morning congestion that's actually coming from bedroom air.

Select everything that applies to your home below for a rough recommendation.

The most effective setup for a family home with allergies is usually one high-CADR unit on the main floor covering the open living area, plus one in the most affected child's bedroom. The bedroom unit doesn't need to be high-CADR — a 200–250 m³/h unit is sufficient for a typical 10–12 m² bedroom at 5 ACH.

Symptoms that are worst on waking are almost always a signal that bedroom air, not living-room air, is the problem to solve.