Context for the latest register update (May, 2022): Our randomized controlled pilot trial was conducted from February until April 2021, following the same methodological procedures described within the clinical trial register. After analyzing the data from the pilot trial we included some updates within the clinical trial register. Summary of changes after the pilot trial: 1) We performed a new sample size calculation, which resulted in a sample size of 700 participants (n=350 in each group). This information was updated within the trial register; 2) We removed the secondary outcome "Ability of the filtering element to inactivate the SARS-Cov-2". The team decided that this outcome would be more appropriately assessed in a controlled laboratory study, and not associated with the clinical trial. Thus, this outcome will be investigated in a secondary study; 3) We decided to include the clinical assessments (Job stress, Quality of life, Musculoskeletal discomfort, Burnout, and Work ability) exclusively as baseline measurements.
