INFLUENZA (FLU) IN THE WORKPLACE

NIOSH Activities: Engineering Infection Controls

Controlling exposures to workplace hazards is a key method of protecting workers. Engineering controls are high on the hierarchy of controls used to protect workers from workplace hazards. Engineering controls remove or reduce a hazard, or they place a barrier between the worker and the hazard. Well-designed engineering controls are preferred to personal protective equipment (PPE) because engineering controls can be highly effective in protecting workers, and they generally place less of the burden upon worker actions. NIOSH researchers are involved in the following research efforts focused on developing and evaluating engineering controls to reduce the spread of infectious disease in healthcare settings.

NIOSH Engineering Control Research on Infection Control

Expedient Airborne Infection Isolation Within Traditional Hospital Environments

General Description: Public reports suggest the U.S. healthcare system does not have enough capacity to isolate patients during a large airborne infectious disease epidemic or bioterrorism event. Government response recommendations mention portable filtration units and other engineering controls needed to isolate surge patients. Little information is available to help with selecting these engineering controls or beginning their use. Also largely unknown is their ability to provide the needed protection. This research activity used off-the-shelf materials to construct prototype expedient airborne infection isolation areas within healthcare facilities. Isolation performance testing involved producing airborne droplet nuclei to represent infectious aerosols. Concentration monitoring of the aerosol in key areas showed airflow patterns, airborne concentrations, and overall levels of isolation. The research identified what is needed to set up and use expedient isolation areas to control airborne infection, it calculates the expected performance of the measures, and it gives guidance for developing and using the areas to meet requirements for isolating airborne infections during surge events.

Key Findings: Key findings of this research are found in the following publications:

• Containment Effectiveness of Expedient Patient Isolation Units
• An Evaluation of Portable High-efficiency Particulate Air Filtration for Expedient Patient Isolation in Epidemic and Emergency Response
• Expedient Methods for Surge Airborne Isolation within Healthcare Settings during Response to a Natural or Manmade Epidemic

Status: Funding ended September 2010. Along with the published papers listed above, another peer-reviewed manuscript is being developed and has not yet been submitted for publication.

Point of Contact: CDC-Info

Airborne Infection Isolation Within Emergency Shelters and Non-traditional Healthcare Environments

General Description: This research builds on the CDC work to develop designs for expedient (or surge) isolation areas to control airborne infection, which were developed for traditional hospital environments. This work applies the control concepts to emergency medical shelters and other non-traditional healthcare environments. Early research showed these techniques could be successful within a variety of healthcare facilities across the United States. Current work translates these proven engineering control techniques for configurations where great masses of patients are treated, such as in a mass-casualty event. The goal is to use training to make these types of protective interventions more familiar to responders and planners. Training events also identify complications that could happen when using the interventions on a large scale, before actually using them in a real emergency. The effort continues to help emergency response officials and their funding authorities to be more familiar with these engineering control interventions, which have a low cost and are effective at reducing exposures.

Relevance to Worker Safety and Health: This project uses research on expedient isolation areas to control airborne infection within healthcare environments. The project translates this research for a nontraditional “infectious” mass casualty environment. Examples of these environments would include setting up cafeterias, gymnasiums, or other shelters to treat large numbers of patients with infectious diseases. This work helps responders be more familiar with control concepts, and the research will report on containing aerosols and reducing in healthcare worker exposures in a mass-casualty environment.

Key Findings: NIOSH researchers developed two prototype designs that apply to emergency medical shelter environments. NIOSH has filed CDC employee invention reports with the CDC’s Technology Transfer Office. The CDC does not plan to patent either invention. One of the two prototype designs can be ordered commercially. The second design, a mobile platform with built-in fan/filter/back-up power options, has been tested and its performance verified, but it is not yet available commercially.

Status: Though funding for this 2-year research activity ended in September 2010, the effort to translate the information continues. This will include developing peer-reviewed and instructional literature, as well as a commercially available designs for expedient isolation areas to control airborne infection. NIOSH is developing a publication on “Expedient Airborne Isolation” to help with rapidly distributing the instructional how-to literature if an airborne epidemic emergency happens. Although potential manufacturing partners have been identified, developing commercial availability options for the mobile platform is on hold, pending more research funding or a triggering event that causes sudden need.

Point of Contact: CDC-Info

Engineering Controls for Infection Control Within Ambulance Patient Modules

General Description: New research at NIOSH focuses on ambulances and their ventilation design, engineering controls, and decontamination. The research seeks to make emergency workers inside ambulances less likely to be exposed to infectious diseases. The research has three parts: (1) evaluating ventilation patterns within the ambulance via surrogate tracer techniques and subsequently identifying ventilation designs and interventions that reduce occupant exposure and airborne contaminant dispersion; (2) building a computational fluid dynamics model of the ambulance interior environment and using this model to improve ventilation design and find how contaminants disperse; and (3) transferring recently proven technology into the smaller-scale interior ambulance environment, verifying that it is effective within that environment, and giving guidance on how to operate the technology when implementing it. This technology uses portable “Total Room and Air” units that use ultraviolet germicidal irradiation to decontaminate air and surfaces in a healthcare treatment environment.

Relevance to Worker Safety and Health: This research will study airflow patterns within a common government-specification ambulance module and evaluate whether these patterns expose emergency response workers to contamination from patients. Researchers will use these findings to identify engineering control interventions to reduce the workplace exposure risk to airborne infectious contaminants. Researchers will also try to reduce the degree and spread of surface contamination throughout the module and driver’s cab. The second phase will study how well ultraviolet germicidal irradiation works as a control between patients and workers to reduce surface contamination as an exposure risk within the patient module.

Key Findings: The baseline computational fluid dynamics model has been completed, confirming the qualitative test findings regarding the chance for EMT exposure to aerosol from patients within the ambulance module.

Status: The first-generation ventilation intervention design is complete and has been installed and tested. Although the prototype’s high-efficiency filtration improved indoor contamination levels, the worker-protective directional airflows were not sufficiently established and will be the focus of future research. The ventilation research has been put on hold until completing the ultraviolet germicidal irradiation disinfection research. Baseline ultraviolet germicidal irradiation energy distribution tests upon the ambulance module surfaces have been completed and became the basis for follow-on research. To date, the ultraviolet germicidal irradiation research has developed two prototype systems: (1) an ultraviolet germicidal radiation tripod to temporarily place in a stationary, unoccupied ambulance to disinfect them, and (2) a built-in ultraviolet germicidal irradiation light package that can disinfect unoccupied ambulance module interiors, whether stationary or mobile. Although testing these prototypes is promising, researchers continue to collect performance data, including energy delivery measurements and surrogate microorganism testing. Completion of the data analysis and initial reporting of the ultraviolet germicidal irradiation data are targeted for late FY16.

Point of Contact: CDC-Info

Study and Optimization of Airflow Design Patterns Within Hospital Airborne Infection Isolation Rooms

General Description: Traditional engineering guidance for designing airborne infection isolation rooms (AIIR) seeks to protect the rest of the hospital by keeping infectious aerosol from migrating by air. Various authorities specify AIIR as an engineering control for healthcare workers. This research uses computational fluid dynamic evaluations to study several worker-exposure scenarios within AIIR and traditional patient rooms. These scenarios include: (1) comparing a bedside healthcare worker’s chance of being exposed through the air in an existing AIIR to a traditional patient room from the same hospital, (2) comparing a bedside healthcare worker’s exposure in a traditional patient room under scenarios with and without the exposure protection of an expedient airborne infection isolation intervention, and (3) comparing a bedside healthcare worker’s exposure in an AIIR as originally designed to a proposed design that uses a heating, ventilation and air conditioning (HVAC) design in an AIIR to protect airflow. The goal is to measure the chance of exposure within each room scenario and to identify areas for future research. Subsequently, design recommendations will be identified and modeled to reduce chances of exposure within the AIIR.

Relevance to Worker Safety and Health: Engineering controls within AIIRs may not adequately protect healthcare workers inside them against airborne exposure to infectious aerosol. This research seeks to reduce the number of times that traditional AIIRs are incorrectly prescribed to control airborne infectious exposures. The research also identifies airflow-specific design parameters within the AIIR that actually give better workplace protection from such exposures.

Key Findings: The computational fluid dynamics research model for an airborne infection isolation rooms was presented at the January 2012 Winter Meeting of the American Society of Heating Refrigeration and Air Conditioning Engineers (ASHRAE). A peer-reviewed journal article, “Assessment of Health-care Worker Exposure to Pandemic Flu in Hospital Rooms” by Ghia et al. was published in the journal ASHRAE Transactions [2012 Jan; 118 (Part 1):442–449]. View the NIOSHTIC-2 citation. A subsequent computational fluid dynamics research model was developed to evaluate exposures in a traditional patient room, both with and without an intervening engineering control in place. These results were presented at the 2015 ASHRAE Winter Meeting. Also published was a corresponding peer-reviewed manuscript by Dungi et al.,“Effectiveness of a Local Ventilation/filtration Intervention for Health-care Worker Exposure Reduction to Airborne Infection in a Hospital Room.” The article appeared in Proceedings of the 2015 ASHRAE Winter Conference, January 24–28, 2015, Chicago, Illinois [Atlanta, GA: American Society of Heating, Refrigeration and Air-Conditioning Engineers].

Status: Funding for this research effort has expired. However, a follow-up computational fluid dynamics research contract will study whether a benefit exists to merging protective expedient isolation design techniques within the negative-pressure containment environment of a traditional AIIR. This study is still underway and is expected to conclude in FY2016.

Point of Contact: CDC-Info