Monitors to Improve Indoor Carbon Dioxide (CO2) Concentrations in the Hospital (MICH)

Monitors to Improve Indoor Carbon Dioxide (CO2) Concentrations in the Hospital: a Randomized, Sham-controlled, Open Label Trial

Ventilation with fresh outdoor air has recently gained considerable attention as a means to reduce the potential risk of indoor aerosol transmission of respiratory pathogens such as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus causing coronavirus disease 2019 (COVID-19). Commercial carbon dioxide (CO2) monitors are increasingly used in schools, long-term care facilities, offices and public buildings to monitor indoor ventilation. However, no formal evidence is available to support the effectiveness of feedback from CO2 monitoring devices. Moreover, modern hospitals have superior indoor air quality control systems. The aim of this prospective pilot randomized controlled trial (RCT) is to evaluate whether CO2 monitoring devices would be useful as a means to further maintain lower indoor CO2 concentrations in hospitals.

In this pilot, randomized, sham-controlled open-label RCT, hospital rooms will be fitted with Aranet4 Home CO2 sensors. Each device will continuously measure indoor CO2 concentrations at 1-minute intervals during 4 time periods: 1. Baseline: staff blinded to CO2 levels displayed on sensor 2-3. Sham/Intervention period: sensors on the same ward will be randomized to placebo (sensor not showing CO2 levels to staff) or Intervention (sensor displaying CO2 levels to staff) in a cross-over design 4. Post-intervention phase (3 weeks post-intervention): staff blinded to CO2 levels Each measurement period will consist of 7 days with no washout period. Our primary hypothesis is that CO2 sensors will record less time (minutes) with elevated CO2 levels during the intervention period, compared to the Sham periods. However, carry-over effects will be investigated by comparing the Intervention periods to the Baseline and Post-intervention phases. Note [February 27, 2021]: due to technical problems with the Aranet4 device Bluetooth connection, outcome data will be analyzed according to measurement data at 2-5 minute intervals (measurements can be made every minute, but data cannot be downloaded with the current version of the app due to technical problems).

Each sensor will be randomized to Sham-Intervention or Intervention-Sham cross-over. Additionally, each sensor will measure CO2 during a baseline and post-intervention phase.

How feasible is it to use CO2 sensors to monitor indoor air quality in hospital? Anonymous online survey during the post-intervention phase

Would you prefer to use CO2 sensors to monitor indoor air quality in hospital in the future? Anonymous online survey during the post-intervention phase

Data will be available upon fulltext print publication in a peer-reviewed journal, for a duration of at least 10 years.

Laurent MR, Frans J. Monitors to improve indoor air carbon dioxide concentrations in the hospital: A randomized crossover trial. Sci Total Environ. 2022 Feb 1;806(Pt 3):151349. doi: 10.1016/j.scitotenv.2021.151349. Epub 2021 Oct 30.