Ergonomics and Human Factors is a discipline focused on ensuring human operators have the right systems, tools, and environments in place to be safe, healthy and productive. We have covered numerous ways that this profession has intersected with the Healthcare and Employee Health and Safety industries throughout the Covid-19 pandemic.
A new study aims to give employers, employees, and the public more information about the efficacy of tools such as face masks, face shields and neck gaiters in blocking cough aerosol. The study used a cough aerosol simulator to measure the amount of propelled aerosol particles using different face coverings.
In summary, the most effective blocking of cough aerosol as reported as a percentage of 100 is as follows but keep reading for some important and additional information and resource links.
- An N95 respirator blocked 99% of coughed aerosol
- A medical grade procedure mask blocked 59% of coughed aerosol
- A 3-ply cotton cloth face mask blocked 51% of coughed aerosol
- A folded, double layer, neck gaiter blocked 60% of coughed aerosol and the same gaiter worn as a single layer blocked 47% of coughed aerosol
- A face shield blocked 2% of the coughed aerosol
Study authors suggest that face masks and neck gaiters are preferable to face shields as source control devices for cough aerosols. Though, that is not the end of the story. The study authors note that the evaluation of appropriate Personal Protective Equipment (PPE) can include considering likelihood of acceptance of use and whether the intent is to prevent the wearer from contracting or dispersing infection. An additional discussion on the merits of deflection as a control mechanism is also included in the paper.
While the N95 respirator comes out the clear leader in the described research, it is important to note that providing employees with a respirator will require an employer to have a respiratory protection program. The Occupational Safety and Health Administration (OSHA) is providing resources for creating a safe working environment during Covid-19 HERE.
At the same time, enforcement of health and safety standards is ongoing and OSHA reports that failure to meet Respiratory Protection requirements as outlined in 1910.134 is the most cited violation employers have faced during the pandemic. A deeper look at specific enforcement actions is provided in: Common COVID-19 Citations: Helping Employers Better Protect Workers and Comply with OSHA Regulations
Additional articles relating ergonomics and human factors practice to the Covid-19 pandemic:
The original study can be found HERE.
Source: William G. Lindsley, Francoise M. Blachere, Brandon F. Law, Donald H. Beezhold & John D. Noti (2020) Efficacy of face masks, neck gaiters and face shields for reducing the expulsion of simulated cough-generated aerosols, Aerosol Science and Technology, DOI: 10.1080/02786826.2020.1862409