This Briefing Note was completed by the Research, Analysis, and Evaluation Branch (Ministry of Health). Please refer to the Methods section for further information.
This briefing note summarizes research evidence and guidance on design strateThis briefing note summarizes research evidence and guidance on design strategies that can be used to mitigate the spread of illnesses that spread through the air in congregate care settings, such as long-term care homes. Detailed supporting evidence and guidance is summarized in Table 1.
*The full version of the Briefing Note including the Appendix can be accessed in the PDF file at the top of the page*
Protecting residents and workers from illnesses that spread through the air is best accommodated by including a mechanical system in facility planning and design that provides adequate ventilation, filtration, and temperature and humidification controls.
- Heating, Ventilation, Air Conditioning (HVAC) Systems: In addition to maintaining other infection prevention and control measures (e.g., mask wearing, physical distancing, hand hygiene, etc.), two reviews, two guidance documents, and a University of Toronto-based ventilation expert recommend improvements to HVAC systems in congregate settings. These include working with an HVAC professional to equip buildings with a well- maintained HVAC system that: 1) has the capacity to achieve at least six air exchanges per hour through ventilation and filtration; and 2) uses a filter with the highest compatible Minimum Efficiency Reporting Value (MERV) rating (ideally MERV 13 or higher), while ensuring the filter is well-sealed and changed regularly.
- Use of Exhaust Fans: Bathroom, showers and kitchens should be equipped with effective and well-maintained exhaust fans that vent outdoors and are always on.
- Other Airborne Infection Control Strategies: Use of portable high-efficiency particulate air (HEPA) filters, installation of upper-room ultraviolet (UV) air disinfection (where safe and feasible), access to natural ventilation (e.g., windows that open), and use of ventilated headboards.
- Building Layout, Density, Signage: Small intentional environments for smaller cohorts of aging residents (e.g., household environments serving fewer than 20 residents) supported by staff in a decentralized manner offer a strong defense against infection transmission (i.e., by reducing or preventing the need for staff to travel around larger buildings and pass through unrelated resident areas and workspaces). Descriptive signage helps visitors and service providers navigate semi-public and semi-private spaces and limit unnecessary mixing. Staff should have a dedicated building entrance and exit that is separate from residents, visitors, and other services.
- Private Rooms: Two studies report that communities with a high percentage of private rooms had significantly lower rates of COVID-19 and fewer deaths.
- Zoning Using Separate Air Systems for Resident Clusters: Having a common HVAC unit in each zone that serves a cluster of rooms minimizes air recirculation among clusters and supports better segregation in the facility, if needed (e.g., as an isolation unit).
- Additional Considerations: Portable non-exhaust fans or air conditioning units should be carefully positioned to avoid creating direct air flow between residents.
Analysis for Ontario
The planning and design of congregate care settings should consider including a mechanical system that provides adequate ventilation, filtration, and temperature and humidification controls.
In addition to improved HVAC systems, a decentralized small-cohort facility design with dedicated staff can reduce airborne disease transmission.
This section below lists and summarizes scientific evidence (systematic reviews, reviews, or single studies) and guidance from the grey literature (e.g., World Health Organization [WHO]) that describe design features that prevent the spread of respiratory infection in congregate living settings, including long-term care (LTC) homes. The information presented is primarily taken directly from the original sources.
The following terms are used throughout this briefing note:
- A heating, ventilation, and air conditioning (HVAC) system comprises the equipment, distribution system, and terminals that provide, either collectively or individually, the processes of heating, ventilating, or air conditioning to a building or portion of a building. Most HVAC systems also incorporate filtration.
- Mechanical filtration involves the use of different types of fibrous media designed to remove particles from the airstream. A portion of the particles in the air entering a filter attach to the fibrous media and are removed from the air as it passes through the filter. The particle removal efficiency of the filter, the rate of air flow through the filter, location of the filter, and size of the particles filtered by the filtration system all contribute to the reduction of indoor particle concentrations.
- Ventilation is the supply/distribution or removal of air from a space using mechanical or natural means. Ventilation can be for the purposes of controlling air contaminant levels, humidity, or temperature within the space. It can be achieved through natural means, such as through openings (e.g., windows, doors) and by passive infiltration. Mechanical ventilation is the active process of supplying air to or removing air from an indoor space by powered equipment such as motor-driven fans and blowers (e.g., HVAC systems, and bathroom or cooking exhaust fans).
*The full version of the Supporting Evidence section can be accessed in the PDF file at the top of the page*
Individual peer-reviewed articles were identified through PubMed and Google Scholar. The search was limited to English sources and therefore may not capture the full extent of initiatives in non-English speaking countries. Full-text results extracted were limited to those available through Open Access or studies made available to the Ministry by our partners. Jurisdictional information was identified using Google and on relevant government websites.
The Medical Subject Heading term “Design, Facilities” was used in combination with keywords to identify relevant articles for this review including: “long-term care”, “residential care”, “aged care”, “congregate living”, and “respiratory infection”.
The COVID-19 Evidence Synthesis Network is comprised of groups specializing in evidence synthesis and knowledge translation. The group has committed to provide their expertise to provide high-quality, relevant, and timely synthesized research evidence about COVID-19 to inform decision makers as the pandemic continues. The following member of the Network developed this Evidence Synthesis Briefing Note:
- Evidence Synthesis Unit, Research Analysis and Evaluation Branch, Ministry of Health. November 4, 2021.