Originally Published on National Collaboration Center for Environmental Health. View original publication here.

Author: Angela Eykelbosh

Maintaining a safe physical distance will be essential to virtually all social and economic activities carried out during the COVID-19 pandemic. However, there are many instances or activities during which it is not possible to remain more than 2 m away from others, or to remember to do so. To address this, the use of transparent physical barriers have been broadly recommended by the Public Health Agency of Canada, the US CDC, the World Health Organization, and many other agencies. These barriers are often made out of acrylic (Plexiglass) or polycarbonate plastics, which are lighter weight, more easily shaped, and have much greater impact resistance than glass. The purpose of this document was to consult with public health and industry to identify best practices in the design, installation, and maintenance of transparent partitions to ensure that they are most protective of public health.

Why use transparent partitions?

Although partitions have been widely in use in healthcare and food service settings for decades, their use in the “new normal” world of business is distinct from either of these. Partitions are proposed to serve three critical functions: 1) intercepting the respiratory droplets that are thought to transmit the virus, 2) re-enforcing physical distancing requirements, even when users are unwilling or forgetful; and 3) reducing reliance on masks, both due to the shortage of these items and user comfort. However, if staff and/or clients will be unmasked on opposing sides of these partitions, it is essential that the partition has been designed, installed, and maintained such that it effectively prevents the co-mingling of droplets (and aerosols) produced by both parties.

Best practices for designing transparent partitions

The most obvious critical factor for a partition is that its dimensions should exceed the breathing zone of partition users (employees and clients) by a wide margin. The breathing zone is the pocket of air from which a person draws breath, and can be visualized as a bubble with a radius of 30 cm (12”) extending from the mid-point between a person’s ears. Thus, the height of the partition must take into account the tallest user, and the way in which s/he will approach or use the partition. For example, if one user is standing and the other sitting, the partition should reflect the height of the standing person. Currently, many partitions being sold for desks are too low to completely shield the breathing zone of a seated person.

The width of the partition should account for user behavior, including the likelihood that users will attempt to move to the side to speak around the barrier. Currently, industry best practice is to make the partition as wide as the surface, desk, or countertop will allow. Some manufacturers are also providing signage or stickers that remind clients to remain behind the barrier.

Transparent barriers often need openings to allow limited interactions (e.g., a document slot, or space for a point of sale terminal). These slots should be kept as small as possible, dependent on the activity, and should be placed so as to not compromise the breathing zone of either user. For example, if one user is standing and passing documents to a seated person on the other side, the document slot (typically 4” x 10”) should be placed off-center, rather than directly in front of the seated person’s face. In some cases, the opening may need to be larger (e.g., to pass packages). In these cases, it may be useful to install a slider or a flexible plastic flap, understanding that this feature will then become a high-touch surface and will need to be sanitized alongside other high-touch surfaces (door knobs, POS devices, etc) throughout the day.  Because the purpose of these partitions is to ensure that one user’s breathing zone is not contaminated by exhalations from another, speaking ports or grates should not be installed through the partition.

Partitions are typically surface-mounted (using brackets or clamps), free-standing, or hung from the ceiling. In general, the partition should be designed so as to minimize airflow around the edges of the partition. Some partition designs include wings or side panels that may be necessary to provide stability (as in free-standing designs), but may also help to further shelter the user’s breathing zone. These side panels may be attached by flexible PVC hinges or tape to prevent airflow through the seams. Hanging partitions, although visually more appealing, may have a large gap between the panel and the countertop, allowing air to flow through. Furthermore, if the partition is able to swing, it may waft air from one user to another. Hanging partitions may also be more difficult to clean (being somewhat mobile). Generally, a surface-mounted or free-standing partition is preferred, although there may be specific circumstances (e.g., a glass jewelry case) in which a hanging partition cannot be avoided.

Installation

Partitions should be installed with safety in mind, taking care not to hinder the user’s escape in an emergency situation. Free-standing or wheeled partitions, especially very large ones, should be used cautiously due to chance of these being knocked over. It may be advisable to use temporary adhesive products to ensure that free-standing partitions remain in place.

Cleaning and maintaining acrylic partitions

Because partitions are intercepting respiratory droplets, they must be treated as contaminated surfaces and should be cleaned regularly according to a set protocol. Partitions that are not touched should be cleaned daily, whereas portions of the partition that are touched (e.g., hands passing through and contacting a soft plastic flap) should be cleaned twice daily, or more frequently if visibly soiled, as with other high-touch surfaces.  

Health Canada has created a list of disinfectants for use against COVID-19. However, many common disinfectants are known to damage acrylic or polycarbonate surfaces, causing them to crack or become cloudy. Proprietary cleaning solutions may not contain detergents or other ingredients sufficient to destroy SARS-CoV-2, the virus that causes COVID-19.  When in doubt, the surface should be cleaned with mild soap and water. If microfiber or other reusable cloths are used to wash or dry the partition, these should be considered contaminated and should be laundered before re-use.

Summary

Physical barriers like acrylic or polycarbonate partitions are thought to provide some limited protection for individuals sharing the same space, first by preventing people from getting too close and also by preventing particles or droplets exhaled by one person from entering the breathing zone of another. If a physical barrier is being used in lieu of a mask for close interactions, then it is essential that the partition has been designed with wide margins to ensure that the breathing zones of both seated/standing users is protected. Even when designed properly, physical barriers must still be used in conjunction with other critical infection prevention and control measures, including environmental cleaning, hand hygiene, respiratory etiquette, and masking for those who are ill (source control). Inspectors and operators should look to their provincial public health guidelines to understand how partitions fit into their overall infection prevention and control strategy.

Key Messages

1. Choose dimensions that protect the breathing zone of the tallest person using the partition. The breathing zone can be thought of as bubble with a radius of 30 cm extending out from the mouth and nose.
2. Pass-throughs or openings should be as small as possible and not located in the breathing zone of either user; do not include speaking ports or grates.
3. Install the partition securely, such that it cannot tip or fall; do not block or impede emergency egress.
4. Surface-mounted partitions with small openings and wings/surrounds are preferred over hanging partitions that can swing or waft air.
5. Clean the partition at least daily with mild soap and water or a compatible disinfectant; discard or launder the cloths used for cleaning.