A new study conducted by University College London (UCL) and University College London Hospitals (UCLH) has revealed that hospital ventilation systems and portable air purifiers (PAPs), designed to reduce the airborne spread of viruses, can sometimes exacerbate the situation instead. Researchers found that while these devices are intended to remove harmful particles, they can also push them into unexpected areas, increasing the risk of infection in certain situations, according to ScienceDaily.
The research, published in the journal Aerosol Science & Technology, tracked the movement of particles in the air similar to those exhaled by patients with COVID-19 or influenza in a hospital outpatient clinic. The researchers examined how particles moved under various conditions, such as with doors open or closed, and with ventilation systems and PAPs turned on.
In some cases, closing doors significantly reduced the spread of particles by up to 97%. However, using PAPs in a waiting room actually increased the spread of particles into an adjacent consultation room by 29%. Built-in ventilation systems also caused particles to travel much farther than expected, sometimes increasing their movement through the clinic by more than five times. Professor Lawrence Lovatt, a study author from UCL Surgery & Interventional Science, noted: "Even in UCLH, a modern hospital built less than 20 years ago, airflow patterns were unpredictable. In older hospitals, where natural drafts are common, the situation is likely even more complicated."
One of the most unusual and significant findings was that the highest concentration of particles in the air sometimes appeared in rooms located far from the source. In one instance, a consultation room situated far from the source had 184% more particles than average, while a room directly opposite the source had 68% fewer than expected.
The study also indicated that PAPs could cause particle accumulation in critical areas, such as the medical station, potentially exposing hospital staff to greater risk of exposure. Dr. Jacob Salmonsmith explained: "While air purifiers do remove viral particles from the air, they can also have unintended consequences. Large air purifiers with big exhaust openings can create airflows that push unfiltered particles farther than they would otherwise travel."
To address these issues, researchers are developing an artificial intelligence system that can predict air movement in hospitals and suggest optimal placement for ventilation systems. Testing is expected to begin within 18 months. The results of this study may also aid in the development of new ventilation guidelines for hospitals, improve infection control, and reduce the risk of airborne virus transmission.
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