Researchers review engineering controls

Researchers are looking to provide some guidance to health care leaders interested in implementing engineering controls — technologies such as natural ventilation, mechanical ventilation, laminar flow, photocatalytic oxidation and germicidal ultraviolet energy — to help reduce respiratory infections, such as influenza and coronavirus.

“Overall, the downstream goal is to assess whether engineering infection control measures are effective in reducing indoor infection transmission,” says Amiran Baduashvili, M.D., associate professor of medicine, University of Colorado — Anschutz Medical Campus. To move toward this goal, Baduashvili, along with Lisa Bero, Ph.D., professor of medicine and public health and chief scientist of the Center for Bioethics and Humanities at the University of Colorado, and other researchers conducted a scoping review of 672 studies to assess currently available evidence on what types of intervention have been studied, how the outcomes have been evaluated and where evidence gaps lie.

This study was funded by and conducted in collaboration with the National Institute for Occupational Safety and Health. The researchers published their results as “Engineering Infection Controls to Reduce Indoor Transmission of Respiratory Infections: A Scoping Review,” in the Annals of Internal Medicine.

Of the included studies, which were published between 1929 and 2024, 606 evaluated environmental samples only, 57 included human participants and nine included sentinel animal subjects. About half of the studies (405) included at least one intervention classified as pathogen inactivation, with 200 involving pathogen removal or air exchange or dilution. Across all studies, about half measured the quantity of viable nonpathogenic organisms from air samples, followed by the quantity of nonbiological particulates or viable pathogenic organisms. Harms, such as toxic byproducts, were rarely measured.

The review revealed that current evidence on engineering infection controls stems primarily from non-human studies.

“We don’t have a large body of evidence that includes human participants,” Baduashvili notes.

As such, facilities managers should proceed with caution when implementing engineering controls. “If hospital facilities managers are integrating new air-cleaning technologies into buildings, it makes sense for them to continue advising the use of all the standard precautions, such as surface sanitization, hand-washing and masking when appropriate, among others,” Baduashvili says.

“In addition, at a minimum, facilities managers should try to determine if the specific technologies in question have been studied in humans, whether they can produce any harmful byproducts and what the best steps may be to mitigate human exposure to those byproducts,” Baduashvili adds.