Air Change Rate and SARS-CoV-2 Exposure in Hospitals and Residences: A Meta-Analysis

Area of Science:

• Environmental Health
• Infectious Disease Epidemiology
• Airborne Transmission

Background:

• The US CDC and WHO recommended increased ventilation and air cleaning to mitigate SARS-CoV-2 inhalation exposure.
• Understanding the relationship between ventilation rates and airborne virus levels is crucial for public health strategies.

Purpose of the Study:

• To evaluate the impact of ventilation and air cleaning rates on SARS-CoV-2 exposure risk.
• To analyze airborne SARS-CoV-2 concentrations and detection rates in relation to air changes per hour (ACH).

Main Methods:

• A meta-analysis of 93 studies involving air sampling in hospitals and residences, published between April 2020 and September 2022.
• Data compiled on SARS-CoV-2 concentration and detection rates, categorized by location type (hospital/residence) and proximity to patient (primary/secondary).
• Correlation analysis between airborne virus metrics and air changes per hour (ACH).

Main Results:

• Hospital wards showed lower airborne SARS-CoV-2 concentrations than residential isolation rooms.
• A negative correlation was observed between airborne virus concentration in primary-occupancy areas and ACH.
• Sample positivity rates were significantly lower in secondary-occupancy hospital areas compared to primary ones, but similar in residential settings.
• ACH and sample positivity rates were negatively correlated, with diminishing effect above 8 ACH.

Conclusions:

• Higher ACH is associated with reduced airborne SARS-CoV-2 concentrations.
• Ventilation appears to be an effective strategy for lowering inhalation exposure risk in both hospital and residential settings.
• While limitations exist, the findings support increased ventilation as a key measure against airborne virus transmission.