Mining Project: Point-of-use Ventilation Systems to Prevent Exposure to Airborne Viruses

Research Summary

Long-term care facility residents and workers, meat/poultry processing workers, and cashiers in grocery/retail stores have experienced a large number of COVID-19 cases. Some of these cases resulted in deaths. At the beginning of the pandemic, long-term care facilities accounted for over one-third of COVID-19 deaths. In these facilities, sources of exposure include infected healthcare personnel and residents. While hospitals have airborne infection isolation rooms, long-term care facilities do not. For workers in meat/poultry processing plants, the sources of exposure are droplets in the air from infected workers and contact with contaminated surfaces. The number of affected meat/poultry processing plant workers was high enough that several meat processing plants were temporarily shut down. Cashiers in various industries are exposed to COVID-19 by interacting with infected customers or by touching contaminated items/surfaces and then touching their eyes, nose, or mouth. As a result, high numbers of grocery store workers were infected.

Long-term care facility workers and residents, meat/poultry processing plant workers, and retail cashiers are exposed to COVID-19 in similar ways, with airborne exposure and contaminated surface contact being the main sources of exposure. These groups could be protected by using a ventilation hood to provide clean air or to extract contaminated air.  This hood could be used in conjunction with barriers. For some workers, it may be beneficial to use a canopy to blow air over the worker, providing clean uncontaminated air to their breathing zone. In these cases, the idea is to protect the worker from contaminated air by providing a constant stream of air flowing over the worker from above.

This pilot project tested a push—i.e., blowing plenum—local ventilation system (LVS) that contained a HEPA filter. The LVS was tested to determine its effectiveness for protection against particles ranging in size from nanometers to microns. The ventilation approach taken is referred to as "point-of-use," meaning that ventilation is provided by the system at the worker’s location rather than relying solely on a building’s HVAC system.

In this project, researchers evaluated a push LVS to protect a worker from being exposed to airborne virus particles. NIOSH applied its extensive experience in developing engineering controls to provide clean air for workers in underground mines. In previous research, NIOSH successfully developed a canopy air curtain (CAC), which is a push system, for protecting miners from respirable dust and diesel exposure. NIOSH is currently working with a company to modify the original NIOSH CAC design for use in mitigating airborne coronavirus exposure for cashiers. The new LVS that is the subject of this project is more compact, uses a HEPA filter, and incorporates a better seal design between the filter and the filter mounting surface to capture nanometer particles in the range of the coronavirus. This coronavirus LVS could be attached to the ceiling with cables or mounted on a portable stand so that it can be positioned directly above a worker.

The evaluation of the LVS described above will be published in the form of a journal article, "Evaluation of a Prototype Local Ventilation System to Mitigate Retail Cashiers’ Exposure to Airborne Particles," in the Journal of Occupational and Environmental Hygiene.