Health hazard evaluation report: evaluation of environmental controls at a homeless shelter associated with a tuberculosis outbreak - Texas.
Martin-SB Jr.; Lawrence-RB; Mead-KR
Morgantown, WV: U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, HETA 2013-0145-3209, 2014 May; :1-42
On May 22, 2013, the National Institute for Occupational Safety and Health (NIOSH) received a request for technical assistance from the shelter manager at a large homeless shelter in Dallas, Texas, linked to an ongoing tuberculosis outbreak. The request asked NIOSH to assess the heating, ventilation, and air-conditioning (HVAC) systems and make recommendations to improve overall environmental controls at the shelter. During an on-site evaluation of the homeless shelter in June 2013, we collected physical and ventilation measurements in all key areas of the facility. We focused on areas where shelter guests typically congregate or spend significant amounts of time. We recorded the make and model number of all air-handling units (AHUs) providing air to the facility, and visually inspected the units. When possible, we measured the air flow rate through supply diffusers and return grilles. The AHUs in place were state-of-the-art and were controlled by a modern building automation system. The ventilation systems were well maintained and functional during our visit, and all AHUs were equipped with proper filter configurations. Despite their excellent condition and maintenance, certain aspects of the ventilation systems' operation could potentially contribute to airborne disease transmission among shelter guests. During our visit, it appeared the AHUs were not providing adequate outdoor air to the occupied spaces under certain occupancy and environmental conditions, as is required by the Dallas Mechanical Code and ASHRAE standards. In addition to alleviating odors and maintaining occupant comfort, outdoor air serves to dilute infectious aerosols, such as Mycobacterium tuberculosis droplet nuclei that are responsible for TB transmission. Since the TB outbreak began, the shelter has taken numerous steps to improve administrative controls, particularly when it comes to identifying guests showing signs and symptoms of TB. We recommend additional improvements to the administrative and environmental controls at the shelter. From a ventilation standpoint, we suggest that all occupied spaces at the shelter complex be supplied adequate amounts of outdoor air, as prescribed by the Dallas Mechanical Code and ASHRAE standards. In addition, we identified an area that should be converted for respiratory separation purposes. This space could serve to separate a guest suspected of having TB or other respiratory diseases from the remainder of the guest population, until medical evaluation, transport or treatment could be obtained. We also recommend developing a written infection control plan, an HVAC operation and maintenance plan, and a written respiratory protection program. Having these plans/programs in place will help the shelter under normal operating conditions, and especially during future outbreaks of respiratory disease.
Region-6; Infectious-diseases; Infection-control; Respiratory-system-disorders; Bacteria; Bacterial-disease; Bacterial-infections; Ventilation; Ventilation-systems; Heating-equipment; Heating-systems; Air-conditioning-equipment; Air-contamination; Indoor-air-pollution; Indoor-environmental-quality; Disease-transmission; Disease-control; Disease-prevention; Environmental-control-equipment; Environmental-engineering; Environmental-exposure; Engineering-controls; Control-technology; Air-flow; Measurement-equipment; Airborne-particles; Equipment-design; Air-quality; Aerosols; Administration; Humans; Sociological-factors; Quality-standards; Respiratory-protection; Public-health; Germicides; Irradiation;
Author Keywords: Temporary Shelters; tuberculosis; environmental controls; ventilation; homeless shelter; airborne infection; airborne transmission; respiratory
Field Studies; Hazard Evaluation and Technical Assistance
Healthcare and Social Assistance; Transportation, Warehousing and Utilities
National Institute for Occupational Safety and Health