Sizing sub-waiting areas outside MRI and CT rooms in an imaging centre

Key takeaways

• Sub-waiting areas outside scan rooms are usually smaller and more enclosed than an imaging centre's main waiting hall.
• Dwell time before a scan is often longer than a quick wait in the main hall, which argues for dedicated coverage.
• Size each sub-area with the CADR formula using its own floor area, not a share of the main hall's figure.
• Two adjacent sub-waiting zones can share one larger unit only if the combined space fits the unit's stated coverage.
• A floor plan review before ordering avoids under-covering a corridor-shaped or oddly proportioned sub-waiting zone.

Why sub-waiting areas outside scan rooms differ from the main hall

An imaging centre's main waiting hall is typically a large, open area where patients check in and wait for their appointment slot to come up. Sub-waiting areas sit closer to the actual MRI or CT room, often in a narrower corridor or a small enclosed alcove where patients wait once they have changed and are next in line.

These sub-areas are usually smaller in floor area than the main hall, but that does not automatically mean they need less filtration attention. Patients here are often waiting longer per visit, sometimes after removing metal objects or changing into a gown, and the space is more enclosed with less natural air movement than an open hall.

Assuming the main hall's coverage extends into these smaller zones is a common sizing mistake, since air purifiers have a stated coverage area that does not automatically reach around corners or through doorways into an adjoining room.

Comparing dwell time and headcount between zones

Dwell time in a sub-waiting area outside an MRI or CT room can run longer than a typical wait in the main hall, since scan appointments are scheduled in fixed slots and patients are often called into the sub-area ahead of their exact time and wait there until they are called in.

Headcount is usually lower here given how scan appointments are scheduled, compared with a main hall holding people across many different appointment types at once. Lower headcount does not mean lower priority, since the smaller room volume and longer dwell time can offset the reduced number of people.

These two factors together, longer dwell time and a smaller enclosed volume, are why sub-waiting areas deserve their own sizing calculation rather than a rough estimate based on the main hall.

Sizing each sub-area with the CADR formula

The sizing method is consistent across any room: required clean-air delivery rate, in cubic metres per hour, equals the room's floor area in square metres multiplied by ceiling height in metres multiplied by a target air changes per hour figure. For a clinical space, that target is generally five or more air changes per hour.

Measure each sub-waiting area's actual floor area and ceiling height rather than estimating from the imaging centre's overall floor plan. A compact sub-area often needs a correspondingly compact unit, such as the Fillo Plus, once you run the calculation with the room's real dimensions.

Our size calculator handles this arithmetic directly and maps the result to the right AIRE model for each zone you enter.

When zones can share one larger unit instead

If two sub-waiting areas sit close together, perhaps outside adjoining MRI and CT rooms with an open sightline between them, they can sometimes share one larger unit rather than needing two separate small ones. This depends on whether the combined floor area falls within a single unit's stated coverage, such as the Classic 400S, and whether the layout allows air to actually circulate between both zones.

A solid wall or a closed door between two sub-areas generally rules out sharing coverage, since the unit's clean air cannot reach a fully separated space. An open alcove layout without a dividing wall is more likely to work.

This is a judgement call best confirmed on site rather than from a floor plan alone, since sightlines and partial partitions are easy to misjudge on paper.

Getting a floor plan review before ordering

Before ordering units for multiple sub-waiting areas, a floor plan review helps confirm which zones are genuinely separate, which can share coverage, and whether any zone has an unusual shape, a long narrow corridor for instance, that changes how effectively a single unit's airflow reaches every corner.

This step also helps you avoid over-ordering. It is easy to default to one unit per sub-area out of caution, when a careful review of the actual layout might show that two adjoining zones are genuinely one connected space for sizing purposes.

Request a free room-by-room Air Report for your imaging centre, and we will work through the main hall and each sub-waiting area as part of the same survey.

Next step

Run each zone's dimensions through our free Air Purifier Size Calculator, then request a full survey to confirm how the main hall and sub-waiting areas fit together.

Frequently asked

How do sub-waiting areas outside scan rooms differ from the main waiting hall?

Sub-waiting areas are usually smaller and more enclosed, and patients often wait longer here per visit than in the main hall, sometimes after changing into a gown ahead of a scheduled scan slot. This combination of longer dwell time and smaller room volume means they need their own sizing calculation rather than assuming the main hall's coverage extends into them.

Can two nearby sub-waiting zones share one larger unit?

Sometimes, if the combined floor area of both zones falls within a single unit's stated coverage and the layout allows air to circulate between them without a solid wall or closed door in the way. This is best confirmed on site, since sightlines and partial partitions are easy to misjudge from a floor plan alone.

What does a floor plan review add before ordering equipment?

A floor plan review, ideally done on site, confirms which zones are genuinely separate, which can share coverage, and whether any zone has an unusual shape that reduces how well a single unit's airflow reaches every corner. It also helps avoid over-ordering units for zones that are actually one connected space.