When crises occur, walls often appear. Whether the danger is an encroaching storm or a global pandemic, humans are remarkably good at erecting physical barriers for protection. In the case of COVID-19, this tendency is understandable. The knowledge that the virus is transmitted effectively through the air suggests that spaces be physically separated. However, as several scientific studies and news outlets have reported, the barriers may actually make matters worse. And now that many retail, dining, educational, and workplace environments are filled with plastic shields of dubious efficacy, we witness the compound problem of exacerbating the pandemic and intensifying our use of physical resources.
Physical barriers play an important role in the Centers for Disease Control and Prevention’s Hierarchy of Controls recommendations. Considered part of “engineering controls” that aim to isolate people from hazards, such approaches “are favored over administrative and personal protective equipment for controlling existing worker exposures in the workplace because they are designed to remove the hazard at the source, before it comes in contact with the worker.” The key is to fulfill what the CDC calls “well-designed engineering controls,” which include ventilation strategies as well as physical shielding devices.
Recognizing that not all barriers have been effective against COVID-19 transmission, environmental health scientist Angela Eykelbosh of the Vancouver, B.C.–based National Collaborating Centre for Environmental Health conducted a rapid review of such installations in non-clinical settings. She identified 13 primary studies conducted between May 2020 and November 2021 that involved virtual simulations as well as direct observation. The virtual models generally predicted the effectiveness of some partitions. One example showed a reduction in deposition aerosol particles between 63% and 92%.
However, real-world settings proved less predictable and more prone to problematic situations. One of the key findings is that physical barriers are often placed such that they obstruct airflow. Because the barriers do not eradicate or remove the virus from a space, the pathogen is still present in the air. If more than one individual is sharing a space behind a partition that is obstructing ventilation, for example, the likelihood of person-to-person transmission could be higher than without the barrier.
Another real-world discovery is that many barriers are not expansive enough to do much good, particularly in cases where individuals can move around a protective partition to communicate. Yet another finding is that barriers are most effective with short-duration exchanges but less so if separated individuals are occupying a space for a longer duration. Additionally, Eykelbosh notes the absence of clear guidelines that can inform the public about proper barrier installation.
The accelerating demand for such single-use polymers amid the pandemic is cause for serious environmental concern. The related concern is increased resource use—particularly since the partition materials are typically considered temporary and disposable. COVID-19 physical barriers are generally plastic—made with materials like polycarbonate, acrylic (plexiglas), or PVC. Such polymers are energy-intensive and derived from fossil fuels. According to Michael Ashby’s book Materials and the Environment (Butterworth-Heinemann, 2009), polycarbonate processing emits an average of six kg of CO2 for every kg of material produced. Plexiglas contributes about 5.5 kilogram of CO2 for each kg of material. By contrast, Portland cement—considered the environmental “problem child” of the construction industry—emits about 1 kilogram of CO2 per kilogram of material. One UK-based company reported a 300% increase in acrylic sheet production from February to March 2020. When combined with the additional disposable polymers being generated from coronavirus-related medical gear, the plastic pollution challenge has been called a “severe transboundary threat to natural ecosystems and human health.”
Rectifying the pandemic-barrier problem will require several steps. First, existing physical partition installations should be checked for common mistakes, as outlined above. If ventilation is impaired, for example, or user behaviors are self-defeating, the barrier should be redesigned or removed. Second, new physical partition designs should consider the emerging best-practice guidelines—such as ensuring that barriers are sufficiently expansive to stop person-to-person aerosol transmission while maintaining adequate airflow from HVAC systems. New installation designs should also consider alternative materials to petroleum-based plastics, such as bioplastics or repurposed glazing. Third, disposal of the plastic partitions should be minimized or eliminated, ensuring that the materials contribute to a viable recycling stream or second-life function.
These steps are simple but will require a concerted effort to fulfill. Nevertheless, with better guidance and forethought, we can utilize materials to reduce virus transmission effectively while avoiding an environmental calamity.
The views and conclusions from this author are not necessarily those of ARCHITECT magazine or of The American Institute of Architects.
