During heavy demolition inside a containment room, the air becomes packed with
microscopic particles—billions, even trillions per cubic meter—which are released by
construction demolition activities. These particles aren’t just dust. They can carry fungi,
mold, bacteria, and viruses. And when the door between the containment room and the
anteroom opens, even with negative pressure in place, a flood of these particles moves
into the anteroom unseen.

This phenomenon is called particulate diffusion, and across an open doorway, negative
pressure alone isn’t enough to stop it.

The anteroom—meant to be a buffer zone—is now contaminated with unseen
particulates. Without sufficient HEPA filtration and workers waiting the appropriate
amount of time in the anteroom, those particles will flow right out the anteroom door into
the hospital’s critical areas—Into hallways, patient rooms, operating rooms, and into
patient lungs.

The result? Hospital-acquired infections. Longer recovery times. And in some cases,
patient death.

Two minutes is the typical wait time in an anteroom equipped with properly designed
recirculating HEPA filtration. In those 120 seconds, the HEPA unit reduces particulate
concentrations to levels lower than those outside the containment zone. Due to the
reduced number of particles, the particles still in the anteroom stay in the anteroom
when the anteroom door is opened, instead of diffusing out of the anteroom into the
hospital’s critical area.

Two minutes can mean the difference between contamination and containment.
Between infection and protection. Between life and death.

Containment isn’t just about design—it’s about action. Here are simple, fast ways to
verify containment is maintained:

• Check the Anteroom’s HEPA unit status – Is it running? Is airflow optimal? What is the filter efficiency?
• Check the efficiency of the HEPA blowers operating in the containment room to establish negative pressure if they are exhausting into a critical area of the hospital.
• Perform a visual inspection – Are all containment barriers sealed? Is the anteroom kept clean of visibly accumulated dust? Check the inspection sheet to determine the last time the walls were wiped down.
• Ensure the containment door or the anteroom door is closed before opening either door. A sight glass/window must be installed in the containment and anteroom door to ensure that both doors are not opened at the same time.
• Using a discrete particle counter, check particulate levels in the anteroom to ensure the calculated wait time is still appropriate.
• Ask your team – Are they periodically checking for any signs of containment breach or unusual activity?

Every time you step into a containment zone, you’re making a promise—to protect
immunocompromised patients, staff, and the integrity of the hospital. Two minutes is all
it takes to keep that promise.

So next time someone asks you, “Is the containment really working?”—you’ll know how
to answer.

And it’ll only take two minutes.