Control Strategies

The Hierarchy of Controls is a “layered defense” framework used in the field of worker health and safety that helps clarify what kinds of interventions should be considered and prioritized when trying to address a workplace hazard.

The levels of the Hierarchy, explained in detail below, are ordered from most effective (elimination) to least effective (PPE), and interventions on multiple levels can and should be combined. When using the Hierarchy as a framework to develop protections against a specific hazard like COVID-19, it is helpful to start at the first level (elimination) and consider what aspects of theater can be addressed at this level (i.e. what activities can be done remotely). If elimination of the hazard is not possible, proceed to each subsequent level to determine whether, and how, that control can be used to address the hazard. This process helps to make sure that the most effective interventions are implemented first and that additional protections are pursued when more effective interventions are not possible.

The levels of the Hierarchy of Controls, along with examples of how they could be used to address COVID-19 in a theater context, are listed below.

Hazard Elimination

Hazard elimination refers to altering a task or process to entirely remove the threat of a potential hazard. This is the most effective way to address a hazard. In a theater context, hazard elimination involves identifying which activities could be conducted remotely, in order to directly eliminate the possibility of virus transmission in the workplace. For example, theaters might consider having administrative staff continue to work from home and moving segments of the rehearsal process online.

Substitution

Substitution refers to replacing a hazard with a non-hazardous alternative when elimination is not feasible. In a theater context, this might involve asking what in-person work routines might be replaced with safer alternatives. For example, outdoor rehearsals could be substituted for indoor ones, always following additional administrative controls (e.g. distancing requirements) and PPE guidelines. This control strategy also involves identifying the minimum number of core people that need to be physically present in the building for any activity.

Engineering Controls

Engineering controls refer to technologies or barriers that are installed to prevent people from encountering a hazard. These can be broadly thought of as “Healthy Building” strategies. Theater companies might ask what changes to their facilities could be made in order to minimize risk. For example, management could consider enhanced ventilation and filtration, the use of portable air cleaners in smaller rooms, enhanced cleaning and disinfection protocols, plexiglass shielding in some locations, and no-touch bathrooms.

Administrative Controls

Administrative controls are protocols, procedures, or rules that are put in place to reduce risk. In the context of theaters managing their response to COVID-19, this control strategy involves policies and procedures which can be used to minimize shared surfaces and maintain sufficient physical distancing. For example, everyone at in-person rehearsals adheres to policies for proximity and physical contact, as well as rules requiring frequent hand washing. Administrative controls at theaters could also include strategies for screening and de-densifying audiences, including measures taken to choreograph crowd flow into and out of performance spaces.

PPE

PPE stands for personal protective equipment and includes items such as gloves or masks worn by people exposed to various hazards. The goal is always to try to reduce the risk of the hazard through the other levels of control before having to resort to PPE. However, this is not always possible, as is the case with SARS-CoV-2. Therefore, universal masking is essential as a control strategy. Importantly, not all masks are created equal. Some cloth masks may provide only 50% capture efficiency for respiratory aerosols, while a common three-layer mask (e.g., blue surgical mask) can provide 70% efficiency. A three-layer mask is the minimum recommended level of protection. When everyone is wearing this type of mask, the combined benefit is 91% exposure reduction, because respiratory aerosols have to pass through two masks. For higher-risk activities, consider masks with higher filtration efficiencies, such as a certified N95 made in the U.S. or certified KF94 made in South Korea.