Health Hazard Evaluation Report 2012-0264-3182 Page 1

Evaluation of Environmental Controls at a Homeless 

Shelter Complex (City Rescue Mission–McDuff Campus) 

Associated with a Tuberculosis Outbreak – Florida

Report No. 2012-0264-3182

July 2013

Stephen B. Martin, Jr., MS, PE

Kenneth R. Mead, PhD, PE

R. Brent Lawrence, MS, GSP

Michael C. Beaty

U.S. Department of Health and Human Services

Centers for Disease Control and Prevention

National Institute for Occupational Safety and Health
Page 2 Health Hazard Evaluation Report 2012-0264-3182

Contents

Highlights ......................................................... i

Abbreviations ................................................. iv

Summary ...........................................................1

Introduction .................................................... 2 

Background ..................................................... 3

Assessment ...................................................... 4

Results & Discussion ...................................... 5

Conclusions ................................................... 17

Recommendations ...................................... 18

Outline of Future NIOSH Involvement .... 22

References ..................................................... 24

Tables ............................................................. 26

Figures ........................................................... 33

Acknowledgements .................................... 38

The employer is required to post a copy of this report for 30 days at or near the 

workplace(s) of affected employees. The employer must take steps to ensure 

that the posted report is not altered, defaced, or covered by other material.
Health Hazard Evaluation Report 2012-0264-3182 Page i

Highlights of this Evaluation

The National Institute for Occupational Safety and Health received a technical assistance 

request from the Duval County Health Department in Florida. The request asked that we 

assess the heating, ventilation, and air-conditioning systems and make recommendations to 

improve overall environmental controls at City Rescue Mission–McDuff Campus, a local 

homeless shelter complex with epidemiological links to an ongoing tuberculosis outbreak.

What NIOSH Did

● We visited City Rescue Mission–McDuff Campus on August 22, 2012.

● We met with representatives from the Duval County Health Department and City 

Rescue Mission–McDuff Campus to discuss the ongoing tuberculosis outbreak.

● We recorded the physical sizes of occupied spaces.

● We measured ventilation air flow into/from occupied spaces.

● We collected information on all shelter air-handling units.

What NIOSH Found

● City Rescue Mission–McDuff Campus was working in conjunction with the Duval 

County Health Department to improve administrative controls to identify guests on 

priority screening lists or those with symptoms of tuberculosis.

● Air-handling units were generally in good working order, but some had improper filter 

configurations installed, and one had standing water inside the condensate pan while 

the AHU itself was sitting in pooled rainwater.

● No fresh outdoor air was being supplied to the occupied spaces by building mechanical 

systems.

● There was no clearly defined area to separate guests suspected of having tuberculosis 

from the general guest population.

● A written respiratory protection plan did not exist.

● Most bathroom exhaust fans were not functional.

What City Rescue Mission–McDuff Campus Should Do

● Continue to work with the Duval County Health Department to improve overall 

administrative controls and help ensure rapid identification of guests suspected to have 

tuberculosis.

● Develop a comprehensive infection control plan with input from the Duval County 

Health Department and Florida Department of Health.

● Modify or augment shelter ventilation systems to provide adequate fresh outdoor air 

to all occupied spaces using a strategy compatible with existing ventilation system 

capacities.
Page ii Health Hazard Evaluation Report 2012-0264-3182

● Strategically reposition supply and exhaust grill locations to improve air flow patterns 

in occupied spaces, particularly in the women’s overnight bunk area.

● Install the highest efficiency air filters possible that is consistent with the proper 

operation of the air-handling units.

● Modify at least one family sleeping room in the women’s overnight facility for alternate 

use as a respiratory separation area.

● Develop and implement a written respiratory protection program that meets the 

requirements of the Occupational Safety and Health Administration’s respiratory 

protection standard 29 Code of Federal Regulations 1910.134.

● Repair or replace non-functional bathroom exhaust fans.

● Develop and implement a written operation and maintenance plan for all complex 

heating, ventilation, and air-conditioning systems, to include a filter replacement 

schedule.
Health Hazard Evaluation Report 2012-0264-3182 Page iii

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Page iv Health Hazard Evaluation Report 2012-0264-3182

Abbreviations

μm Micrometer

AHU(s) Air-handling unit(s)

ACH Air changes per hour

AII Airborne infection isolation

ANSI® American National Standards Institute

ASHRAE® American Society of Heating, Refrigerating and Air-Conditioning Engineers

CDC Centers for Disease Control and Prevention

cfm Cubic feet per minute

CFR Code of Federal Regulations

DCHD Duval County Health Department

DRDS Division of Respiratory Disease Studies

DTBE Division of Tuberculosis Elimination

FGI Facility Guidelines Institute

HEPA High-efficiency particulate air

HVAC Heating, ventilation, and air-conditioning

ICP Infection control plan

MERV Minimum efficiency reporting value

NCHHSTP National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention

NIOSH National Institute for Occupational Safety and Health

O&M Operation and maintenance

OSHA Occupational Safety and Health Administration

RH Relative humidity

TB Tuberculosis
Health Hazard Evaluation Report 2012-0264-3182 Page v

Mention of any company or product does not constitute endorsement by NIOSH. In 

addition, citations to websites external to NIOSH do not constitute NIOSH endorsement 

of the sponsoring organizations or their programs or products. Furthermore, NIOSH is not 

responsible for the content of these websites. All web addresses referenced in this document 

were accessible as of the publication date of this report.
Health Hazard Evaluation Report 2012-0264-3182 Page 1

Summary

In May 2012, the National Institute for Occupational Safety and Health (NIOSH) received a 

request for technical assistance from the Duval County Health Department as part of its response to an ongoing tuberculosis (TB) outbreak among homeless persons in Florida. The request asked NIOSH to assess heating, ventilation, and air-conditioning (HVAC) systems and 

make recommendations to improve overall environmental controls at four homeless facilities 

with epidemiologic links to past or ongoing TB disease transmission.

During an on-site evaluation of the City Rescue Mission–McDuff Campus homeless shelter 

complex in August 2012, we collected physical and ventilation measurements in all key areas 

of the facility. We focused on areas where 

guests typically congregate or spend significant amounts of time. We recorded the 

make and model number of all air-handling 

units (AHUs) providing supply air to the 

facility, and visually inspected the units. 

When possible, we measured the air flow 

rate through supply diffusers and return 

grilles. 

The ventilation systems in place could have 

contributed to airborne disease transmission 

among shelter guests. With the exception 

of some improper filter configurations and 

standing water inside one unit, the AHUs 

appeared adequately maintained and were 

fully operational. Unfortunately, none of 

the AHUs provided fresh outdoor air to the 

occupied spaces, as required by the Florida 

Building Code and the American Society of 

Heating, Refrigerating and Air-Conditioning 

Engineers design 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, City Rescue Mission–McDuff Campus 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 are supplied adequate amounts of outdoor 

air. In addition, we identified areas that could be converted for use as respiratory separation 

areas. These spaces could serve to separate guests suspected of having TB or other respiratory diseases from the remainder of the guest population, until medical evaluation, transport 

NIOSH investigators conducted an assessment of environmental controls at the 

City Rescue Mission–McDuff 

Campus, a homeless shelter 

complex linked to an ongoing 

tuberculosis outbreak. The investigation revealed problems 

with the existing environmental controls, along with needed 

improvements in administrative controls and respiratory 

protection. Detailed recommendations are provided in 

this report to improve the 

shelter environment and reduce the likelihood of disease 

transmission.
Page 2 Health Hazard Evaluation Report 2012-0264-3182

or treatment could be obtained. We also recommend developing a written infection control 

plan, 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 any future outbreaks of respiratory disease.

Introduction

Since 2004, the Duval County Health Department (DCHD), in conjunction with the Florida 

Department of Health and U.S. Centers for Disease Control and Prevention (CDC), has 

linked over 100 cases of active tuberculosis (TB) disease, resulting in 14 deaths, to a cluster 

having matching genotype results (PCR00160 or FL0046) in Duval County, Florida. Roughly half of the cases of active TB disease have been identified since 2010. Of the 100 cases, 

79% had a history of homelessness, incarceration, or substance abuse, with 43% being homeless within one year of diagnosis.

In response to the ongoing outbreak, a team of epidemiologists from the CDC National 

Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention (NCHHSTP), Division of 

Tuberculosis Elimination (DTBE) conducted an on-site investigation in February and March 

2012. In their report dated April 5, 2012, the CDC team included a recommendation to 

improve environmental controls at homeless facilities implicated in possible disease transmission. On May 22, 2012, the Division of Respiratory Disease Studies (DRDS), National 

Institute for Occupational Safety and Health (NIOSH), CDC received a request for technical 

assistance concerning the TB outbreak in Duval County. The request was made by a CDC 

Public Health Advisor temporarily assigned to Duval County. The request specifically asked 

NIOSH to evaluate shelters’ heating, ventilation, and air-conditioning (HVAC) systems and 

make recommendations to improve overall environmental controls. The request was initially 

made for an assessment at one homeless shelter. However, in subsequent discussions with 

the TB Program Manager at DCHD, a CDC Public Health Advisor with the Florida Department of Health, and representatives from CDC/NCHHSTP/DTBE, the request was expanded 

to include four facilities that provide assistance to the homeless and which had epidemiologic 

links to past or ongoing TB disease transmission.

In response to the expanded request, a NIOSH team visited the four facilities in August 

2012. This report describes the measurements and associated findings from our assessment 

at the City Rescue Mission–McDuff Campus. It details and prioritizes our recommendations 

for improving environmental controls at the shelter, and outlines the current plan for future 

NIOSH involvement. 

Keywords: NAICS 624221 (Temporary Shelters), tuberculosis, environmental controls, ventilation, homeless shelter, airborne infection, airborne transmission, respiratory
Health Hazard Evaluation Report 2012-0264-3182 Page 3

Background

Tuberculosis and Homeless Populations

TB is a disease caused by Mycobacterium tuberculosis (M. tuberculosis) bacteria. When a 

person with active TB disease coughs or sneezes, tiny droplets containing M. tuberculosis 

may be expelled into the air. Many of these droplets dry, and the resulting residues remain 

suspended in the air for long periods of time as droplet nuclei. If another person inhales 

air that contains the infectious droplet nuclei, transmission from one person to another may 

occur. Homeless people have been identified as a high-risk population for TB infection and 

disease since the early 1900s [Knopf 1914]. With the increase in homelessness in the United 

States since the 1980s, TB among homeless persons has become a subject of heightened 

interest and concern [CDC 1985; 1992; 2003a,b; 2005a; Barry et al. 1986; Slutkin 1986; McAdam et al. 1990; Nolan 1991].

City Rescue Mission–McDuff Campus 

The City Rescue Mission–McDuff Campus is located on the former campus of Trinity Baptist College. The campus houses the administrative offices for City Rescue Mission, which 

serves nearly 300,000 meals a year and provides the homeless with clothing, emergency services, residential recovery, and skills and employment programs. It is also the primary location for the mission’s New Day Workforce and LifeBuilders programs. The New Day Workforce Program offers job-related training to assist shelter guests in obtaining employment. 

Computer training, academic tutoring and many other individualized services are available. 

The LifeBuilders program is a faith-based, 15-month residential recovery program to ultimately enable participants to relearn how to care for themselves and their families. Men and 

women enrolled in the LifeBuilders program reside on McDuff Campus. Participants of the 

LifeBuilders program join in a variety of education and recovery services. Upon entering 

the program, participants receive an evaluation and a recommended program plan based on 

the individual’s needs. While enrolled in the program participants are provided food, shelter, clothing, housing, medical care, and optional legal services. The LifeBuilders program 

also provides life skills training, course work leading to GED, and literacy programs. Approximately 75 staff members work at the McDuff campus. Of those, about 30 have routine 

contact with the guests residing there.

The campus consists of a four-story brick administration building, two separate buildings 

where men and women sleep, a two-story brick chapel, and several free-standing cottages. 

The chapel and free-standing cottages were not assessed as part of the NIOSH visit. The administration building is equipped with four central AHUs, each providing ventilation to one 

floor of the building. Supply air from each AHU travels through fiberglass-wrapped, galvanized ductwork to supply vents in the occupied spaces. There are no return grilles in most 

of the evaluated occupied spaces. All return air travels back to the AHUs via plenum space 

above the drop ceilings. Return air migrated into the plenum space via loose ceiling tiles and 

around light fixtures. Some spaces had return air grilles (e.g., first floor assembly/dining 

room), other dedicated return air paths into the plenum may have been present within administrative and other areas not accessed as part of this survey. The plenum spaces for all four 
Page 4 Health Hazard Evaluation Report 2012-0264-3182

floors feed a common vertical chase that extends to all four AHUs, so return air from one 

floor may be recirculated by an AHU on another floor. The first floor of the administration 

building houses the main reception area with a dining room, kitchen, and hospitality room on 

one side, and a medical clinic and chiropractic clinic on the other. The second floor houses 

staff offices and a large board room. Women participating in the LifeBuilders program live 

on the third floor of the building. The third floor has 16 separate living spaces, with bathroom and shower facilities, a fellowship room, a laundry room, and an exercise room. Each 

living space can house up to 3–4 women, if necessary. There were 24 women housed on the 

floor during the NIOSH visit. The fourth floor of the administration building contains additional staff offices, four classrooms, two computer laboratories, and a small library. 

The one story brick women’s sleeping facility was recently renovated to shelter women 

needing an overnight stay. The women are checked-in and screened at the New Life Inn in 

another part of town, prior to being transported to McDuff Campus for the night. Most of the 

interior space houses a large barracks-style sleeping area with 21 bunk beds (42 total beds) 

and an associated bathroom/shower facility. Women without children sleep in this bunk area. 

To accommodate women with children, the building has four individual family sleeping 

rooms with two bunk beds in each. The family sleeping rooms all share a separate bathroom/

shower area. Two central AHUs installed in the ceiling plenum above the drop ceiling provide ventilation to this building. Supply and return air travel through galvanized and fiberglass flex duct to/from supply vents and return grilles. The building housing the women’s 

sleeping facility also contains a small dental clinic, which was closed during our visit. From 

the outside, the dental clinic appeared to be ventilated by two recirculating window-type airconditioners. 

The men’s sleeping area consists of a single-story brick building that formerly served as two 

small street-front stores. There are no windows in the building. The structure houses 23 

bedrooms, four bathroom/shower rooms, two lounge/prayer areas, a large recreation room, 

and a weight room. Each bedroom in the building sleeps up to four men in bunk beds, and 

approximately 65 men are housed in the facility at a time. The men living in this facility are 

in the final 12 months of the LifeBuilders program, having completed the first 3 months of 

the program at a City Rescue Mission shelter in another part of Jacksonville. Two central 

AHUs serve the building. Supply air travels through galvanized and fiberglass flex ductwork 

to vents in the occupied spaces. The central AHUs use the corridors as a return air plenum. 

No functional return grilles exist in the rooms/occupied spaces, so return air travels through 

cracks and leaks into the hallways and through the hallways towards large return air grilles 

which transmit the return air directly back to each AHU. 

Assessment 

On August 20, 2012, an opening meeting was held at the Duval County Health Department. 

An update was given on the current status of the ongoing TB outbreak among the homeless 

population, and we provided background information on NIOSH, the nature of the technical 

assistance request, and the ventilation measurements we planned to collect at each facility. 
Health Hazard Evaluation Report 2012-0264-3182 Page 5

Aside from NIOSH and DCHD staff, representatives from McDuff Campus and two of the 

three other homeless facilities to be visited during the week were in attendance.

We arrived at City Rescue Mission–McDuff Campus on Wednesday, August 22, 2012 and 

signed into the building. After we unloaded our equipment, the program operations manager 

provided us with all available floor plans of the campus and led us on a tour of the entire facility. After the tour, we began taking physical and ventilation measurements in all key areas. 

We focused on areas where guests typically congregate or spend significant amounts of time, 

but measurements were taken throughout the administration building (excluding the second 

floor where only staff offices are located), women’s overnight sleeping facility (excluding 

the dental clinic that was closed during our visit), and the men’s sleeping facility. We did not 

collect measurements in the chapel or the cottages on the premises during our visit.

We recorded the make and model number of air-handling units (AHUs) providing supply air 

to occupied spaces, and we visually inspected all of the units. When possible, we measured 

the air flow rate through supply diffusers and return grilles using a TSI Incorporated (Shoreview, Minnesota) Model 8373 Accubalance Plus equipped with an air capture hood appropriately sized to accommodate each supply diffuser and return grille. The Model 8373 measures 

volumetric air flow rates of 30–2000 cubic feet per minute (cfm) with an accuracy of ±5% of 

the reading and ±5 cfm. The Accubalance Plus is also equipped with a directional air flow indicator that provides confirmation of flow direction. We determined the approximate internal 

volume of the measured spaces with either a standard tape measure or a Zircon Corporation 

(Campbell, California) Model 58026 LaserVision DM200 laser distance measuring device. 

The device accurately measures up to 200 feet and has function keys for calculating the area 

and volume of a room for HVAC load formulas. When the existence of air flow or the air 

flow direction was questioned, we used a Wizard Stick hand-held fog generator (Zero Toys, 

Concord, Massachusetts) to confirm and visualize the air flow pattern.

After recording our measurements, we met briefly with the McDuff Campus programs operations manager on August 22, 2012, to discuss our general findings from the day’s assessement. A formal closing meeting for our on-site response to the technical assistance request 

for all four facilities was held on August 23, 2012, at the DCHD. This meeting provided us 

an opportunity to discuss our general findings with representatives from the Duval County 

Health Department. 

Results and Discussion

General Tuberculosis Infection Controll

All tuberculosis control programs should include three key components: administrative controls (e.g., intake questionnaires and policies), environmental controls (e.g., ventilation and 

filtration), and a respiratory protection program. Ideally, environmental controls and respiratory protection should supplement aggressive administrative controls. Detailed explanations 

for each of these key control elements, as well as a discussion on the hierarchy of their implementation, are outlined in CDC’s Guidelines for Preventing the Transmission of Mycobacte-
Page 6 Health Hazard Evaluation Report 2012-0264-3182

rium tuberculosis in Health-Care Settings, 2005 and Prevention and Control of Tuberculosis 

in Correctional and Detention Facilities: Recommendations from CDC [CDC 2005b, 2006]. 

In high risk environments, such as homeless shelters, or in areas where administrative controls alone are inadequate, environmental controls and respiratory protection should be used 

as secondary and tertiary levels of control, respectively.

Administrative Controls

During our visit, and in previous conversations with representatives from DTBE, the Florida 

Department of Health, DCHD, and McDuff Campus, it was apparent that limited TB administrative controls were in place at the shelter complex prior to the current disease outbreak. 

However, efforts were taken to improve the overall administrative controls in place at the 

time of the site visit. Employees and volunteers were trained on the symptoms of TB disease and prevention of TB transmission. Additionally, intake screening procedures are now 

in place to help identify guests on target screening lists, or others suspected of having TB, 

and refer them to DCHD for critical medical screening. These procedures will help identify 

infected individuals more rapidly in the future and serve to help keep infected guests away 

from those that are healthy. 

We cannot overstate the importance of having robust administrative controls in place. As 

with most homeless facilities, McDuff Campus frequently provides services to large numbers 

of guests in very close proximity to one another. This is particularly the case in the administration building’s first floor dining room and the third floor women’s LifeBuilders sleeping 

areas, the women’s overnight sleeping area, and the men’s facility. Even the best ventilation 

systems are incapable of totally preventing the spread of disease between guests who are 

close to one another. Thus, identifying people with suspected disease, keeping them separated from the general guest population, and following up with appropriate medical evaluations 

and treatment (if necessary) are the most important elements of reducing or eliminating the 

spread of disease. While enhancing administrative controls is a significant step, the development of a written TB Infection Control Plan (ICP) for the campus should be considered. 

At the time of the NIOSH investigation, no such ICP was reported to exist. Information on 

creating detailed ICPs and TB ICP templates for homeless shelters can be found at the Curry 

International Tuberculosis Center website at http://www.currytbcenter.ucsf.edu/. Collaborating with DCHD and the Florida Department of Health would serve to further strengthen the 

written plan. These ICPs are particularly useful when overall TB infection control requires 

the coordination and subsequent follow-up of different agencies. In response to this current 

TB outbreak, there was good communication and coordination between McDuff Campus and 

DCHD. However, the process should be formally documented in a protocol or checklist format. This ensures that each time there is a TB-related incident, all necessary agencies understand their responsibilities and perform their necessary predetermined actions in a consistent 

manner. Incorporating the input of staff involved in the maintenance and operation of facility 

ventilation systems into the overall infection control program strengthens the program and 

provides these staff members with additional insight as to what ventilation requirements are 

necessary to prevent and/or isolate TB disease. Input from the ventilation staff should be 

sought during the formal creation of the ICP and during subsequent revisions to the plan. 
Health Hazard Evaluation Report 2012-0264-3182 Page 7

Environmental Controls

General Ventilation System Information

General information on the AHUs in the assessed areas of McDuff Campus, including the 

areas served by each unit, is provided in Table 1. None of the AHUs delivered fresh outdoor 

air into the buildings. All AHU air filters are reportedly changed monthly and were replaced 

just prior to the NIOSH visit. As shown in Table 1, all four AHUs in the administration 

building had filter sizes/configurations that differed from manufacturers’ recommendations. 

While the filters in place provided some filtration, the level was uncertain as the deviation 

from intended design provides ample opportunity for filter failure and bypass. We were 

unable to safely determine if filters were in place in the two AHUs serving the women’s 

overnight facility. However, there were low-efficiency filters in place inside the return air 

grille openings leading back to each of the AHUs. If filters are correctly in place inside the 

AHUs, the filters in the return air grilles would provide some improved level of filtration. On 

the other hand, if proper filters are not installed inside the units, then overall filtration is less 

than preferred. Figure 1 shows the filters in the return air grille for AHU Women-1 which 

serves the women’s overnight bunk area. The photograph clearly shows the filters have been 

pulled out of proper position due to the suction of the AHU fan. A similar effect, though not 

as severe, was noticeable with filters inside the return air grille back to AHU Women-2. If 

adequate filters are also installed inside the AHUs, this bypass is not of major concern. If 

the AHUs are not equipped with filters, those in the air return grilles should be removed and 

proper filters installed in the AHUs themselves. The two AHUs serving the men’s facility 

were both equipped with filters, although the recommended configuration for AHU Men-2 

was unknown because a model number for the unit could not be determined. 

The mechanical spaces housing the AHUs in the administrative building were generally clear 

and free of clutter. On the day of our visit, all of the inspected AHUs were operational and 

capable of maintaining temperature and air flow. However, there was a substantial amount 

of standing water inside AHU Men-2 (Figure 2). Additional water was pooled outside of 

the unit. It was unclear whether the standing water inside the AHU resulted from normallyoccurring condensate inside the unit or whether the pooled rainfall surrounding the outside 

of the AHU was leaking into the pan or perhaps interfering with the condensate pan’s ability 

to drain. Whatever the reason, there should never be standing water inside an AHU so the 

issue needs to be resolved. Excess moisture inside an AHU is a recognized contributor to the 

development of microbial growth of public health concern [NIOSH 2013]. Proper sloping 

of condensate drain pans and clean unobstructed drain lines should eliminate these moisture 

accumulation problems. 

Filtration

All of the ventilation filters used at McDuff Campus were Flanders Corporation (Washington, North Carolina) Pre Pleat 40 LPD pleated filters. The Pre Pleat 40 LPD filters have 

an American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) 

Minimum Efficiency Reporting Value (MERV) of 8, which corresponds to a removal efficiency of greater than 70% for 3.0 to 10 micrometer (μm) particles [Flanders 2011; ANSI/

ASHRAE 2007]. However, MERV 8 filters are only around 25% efficient at filtering particles in the 1.0–3.0 μm size range, which includes droplet nuclei responsible for M. tuberculosis transmission [ANSI/ASHRAE 2007]. 
Page 8 Health Hazard Evaluation Report 2012-0264-3182

To prevent the spread of M. tuberculosis, air filters should provide a removal efficiency of 

greater than 90% of particles in the 1.0-3.0 μm size range (corresponding to a MERV 13 or 

higher). During any future HVAC design modifications, system evaluations, or retrofits, the 

selection of filters for use in the AHUs, especially those serving the three main overnight 

sleeping areas, should be closely examined. Care should be taken when choosing more efficient filters, because increased efficiency is typically associated with increased pressure drop 

across the filter (resistance to air flow). Filters in the AHUs should have the highest possible 

efficiency (i.e., highest MERV rating) while still maintaining the air flow required for conditioning and outdoor air supply through each system.

Preventive Maintenance

The ventilation system preventive maintenance program at McDuff Campus was coordinated 

by the facilities manager. With the exception of the filter bypass issue with AHUs Women-1 

and Women-2, and the condensate/flooding issue with AHU Men-2, all of the AHUs were 

fairly clean and appeared to be adequately maintained. The facilities manager informed us 

that the ventilation filters are changed monthly. Unfortunately, there is no written plan outlining the preventive maintenance schedules and procedures for HVAC systems. A written 

HVAC Operation and Maintenance (O&M) Plan should be developed. Currently, all preventive and emergency maintenance is managed, scheduled, and coordinated by the facilities 

manager. Actual tasks are performed by staff, volunteers or contractors, depending upon 

complexity. While this seems to be effective at the present time, there could be a void if the 

facilities manager leaves his current position or is unavailable for any significant period of 

time. Combining all maintenance tasks, schedules, procedures, and training requirements 

into a written plan would ensure that all equipment is properly maintained at appropriate 

time intervals and that any emergency maintenance issues are addressed correctly. A detailed 

plan would also ensure that the quality of work remains consistent as staff changes. Once 

developed, this written plan should be revised periodically to be current with any ventilation 

system and equipment modifications at the facility.

Ventilation Measurements and Indoor Air Quality

An adequate supply of outdoor air, typically delivered through the HVAC system, is necessary in any indoor environment to dilute pollutants that are released by equipment, building 

materials, furnishings, products, and people. In the State of Florida, the 2010 Florida Building Code mandates “minimum requirements to safeguard the public health, safety and general welfare through structural strength, means of egress facilities, stability, sanitation, adequate 

light and ventilation, energy conservation, and safety to life and property from fire and other 

hazards attributed to the built environment and to provide safety to fire fighters and emergency responders during emergency operations [ICC 2011].” The Florida Building Code applies 

to the “construction, alteration, movement, enlargement, replacement, repair, equipment, use 

and occupancy, location, maintenance, removal and demolition of every building or structure or any appurtenances connected or attached to such buildings or structures” throughout 

the state. The Code is based on a variety of model building codes and consensus standards 

from national organizations, which have been modified to fit Florida’s specific needs, when 

necessary. When it comes to ventilation standards, in most cases, the Florida Building 

Code has adopted the recommendations published in American National Standards Institute 
Health Hazard Evaluation Report 2012-0264-3182 Page 9

(ANSI)/ASHRAE Standard 62.1-2010: Ventilation for Acceptable Indoor Air Quality. These 

ASHRAE recommendations provide specific details on ventilation for acceptable indoor air 

quality [ANSI/ASHRAE 2010a]. 

The 2010 Florida Building Code and ASHRAE 62.1-2010 recommend outdoor air supply 

rates that take into account people-related contaminant sources as well as building-related 

contaminant sources. Similarly, exhaust air flow rate requirements for some spaces are also 

listed. Although there are no specific guidelines for homeless shelters and related facilities, 

there are published guidelines applicable to McDuff Campus. These outdoor air supply and 

exhaust air requirements are summarized in Table 2. Table 2 also lists the default occupant 

densities for various spaces. These default values, given in terms of number of occupants per 

1000 square feet, are provided by the Florida Building Code and ASHRAE to assist building 

and HVAC system designers when actual occupant densities are unknown. Although actual 

occupant densities for the occupied spaces inside McDuff Campus facilities are generally 

known, the default values still serve as a reference to determine whether the occupant density 

in a given space is higher or lower than what is considered typical.

The physical and ventilation measurements collected are presented in Table 3. The secondto-last column of the table presents the actual occupant densities in each space. Values 

preceded by an asterisk (*) denote areas with occupant densities above typical values (i.e., 

higher than the default values presented in Table 2). High occupant densities are not solely 

indicative of ventilation problems. For instance, the sitting rooms off rooms F3 and F10 on 

the third floor of the administration building with high densities are typically only occupied 

by two people at a time. In these cases, the occupant densities are high simply because the 

sitting rooms are smaller than typical living rooms. However, the overnight bunk area and all 

four family sleeping rooms in the women’s overnight facility show high occupant densities 

because many people actually sleep in close proximity to one another. In these cases, special 

consideration should be given to air flow patterns in the spaces to minimize the potential of 

exhalations from one person passing through the breathing zone of multiple other people. 

This is especially true when airborne disease transmission is a concern. 

The last column in Table 3 presents the outdoor air requirements for each space, as established by the 2010 Florida Building Code and ASHRAE. As previously noted, none of the 

AHUs at McDuff Campus were delivering fresh outdoor air into any of the assessed buildings. In individual cases, an existing AHU may not have the tempering capacity to incorporate the introduction of outdoor air. If such capacity is available, introducing outdoor air 

through the AHUs would require some modifications and would result in increased annual 

energy costs. However, it is important to ensure that all occupied spaces at McDuff Campus are receiving adequate amounts of fresh outdoor air to reduce the potential for airborne 

disease transmission and to improve indoor air quality. In addition to alleviating odors and 

better maintaining occupant comfort, outdoor air serves to dilute infectious aerosols, such as 

M. tuberculosis droplet nuclei. 

Two common approaches could be employed by McDuff Campus to introduce outdoor air 

into the occupied spaces (or a combination of the two). The first approach would be to make 
Page 10 Health Hazard Evaluation Report 2012-0264-3182

the necessary modifications to the existing AHUs to allow them to bring in the required 

outdoor air. This would initially require evaluation, by a knowledgeable HVAC engineer (a 

reputable ventilation or engineering design contractor that is familiar with ASHRAE, Facility 

Guidelines Institute (FGI), and CDC guidelines and recommendations), of each AHU’s conditioning capacity to determine if it can handle the additional tempering and dehumidification burden introduced by the outdoor air. The AHU system modifications would require the 

installation of outdoor air intakes and dampers into each mechanical space housing an AHU. 

Depending upon the age/condition of some of the AHUs, replacement of an older AHU could 

be a cost-effective contribution to this approach. Although this may be the simpler of the 

two solutions and could require the least capital expense, it may cost significantly more in 

energy over time. In their current configurations, the AHUs are simply recirculating air that 

is relatively close to the desired indoor temperature and humidity conditions. After circulating through the occupied space, this air requires less conditioning to return it to the desired 

delivery temperature and humidity levels. Once outdoor air is mixed in with the room return 

air, the mixed air stream introduced to each AHU will be further from the desired indoor 

conditions for most of the year. Each AHU will then need to work harder to dehumidify and 

temper the mixed air stream. 

A second common method of bringing outdoor air into the buildings would be to install 

dedicated outdoor air systems. This would involve installing a completely new AHU with 

ductwork extending to all occupied spaces of the administration building, with separate 

dedicated outdoor air systems for the men’s and women’s facilities. For the administration 

building, the new AHU should be sized to provide adequate outdoor air flow for the entire 

building (approximately 2500–3000 cfm) while also providing the entire capacity to temper 

and dehumidify this outdoor air. Similarly, the new AHUs for the men’s and women’s facilities would need to provide around 650 cfm and 450 cfm of outdoor air, respectively. Each 

new AHU should provide tempered and dehumidified (supercooled to 45°F–50°F dew point) 

outdoor air to each space (or existing AHU) in quantities necessary to meet Florida Building 

Code and ASHRAE outdoor air requirements. Terminal reheating or blending of this air with 

air delivered by the primary AHUs may be necessary to prevent thermal discomfort from the 

supercooled outdoor air. Conversely, multiple smaller dedicated outdoor air systems could 

serve the same purpose as one large system for a particular building. Regardless of how it is 

accomplished, the major advantage of the dedicated outdoor air systems is that they would 

not require major modifications to the existing AHUs, which would simply continue to recirculate air through the spaces they serve while providing air filtration, heating and cooling. 

The dedicated outdoor air systems would certainly require more capital expense and more excessive renovations for the required ductwork than the first option, but it could also provide 

significant energy cost savings, making it a more viable long-term solution.

A knowledgeable HVAC engineer should be consulted to discuss these and other potential 

options for introducing outdoor air into the McDuff Campus buildings. Although we did 

not access the small dental clinic in the same building with the women’s sleeping facility, it 

appeared from the outside that the space is ventilated by two small window-type air-conditioners (assuming that both were functional). These units did not appear to provide outdoor 

air to the dental clinic. Various dental procedures have been identified as likely to produce 
Health Hazard Evaluation Report 2012-0264-3182 Page 11

aerosols, including potentially infectious bioaerosols. The dentist and any patients waiting 

for treatment in that space could potentially be exposed to infectious aerosols. Although 

there are currently no national or state consensus standards for ventilation of dental clinics, it 

is essentially analogous to a medical exam room. Therefore, the dental clinic should be provided with at least 6 total air changes per hour (ACH) and at least 2 ACH of fresh outdoor air 

[ASHRAE/ASHE 2008]. Additionally, if one does not already exist, an exhaust fan should 

be installed to maintain the clinical space under negative pressure any time dental procedures are being performed. Additional air cleaning through the use of engineering controls 

(e.g. portable high-efficiency particulate air (HEPA) filtration units and directional airflows) 

may also be desired due to the potential for higher TB disease risk among patients seen at 

this clinic. There are special design precautions that apply to the safe storage, delivery and 

recovery of nitrous oxide if it is used as an analgesic/anesthetic gas in this clinic. NIOSH 

engineers can provide additional guidance upon request. 

The CDC TB Guidelines specifically address the issue of potential TB exposures within dental settings. As with other exposure settings, the key protective factor is prompt and accurate 

screening. For a patient with suspected or confirmed TB disease, non-urgent dental treatment 

should be postponed and these patients should be promptly referred to an appropriate medical 

setting for evaluation of possible infectiousness. If urgent dental care must be provided for a 

patient with suspected or confirmed infectious TB disease, the dental care should be provided 

in a setting that meets the requirements for an Airborne Infection Isolation Room (AII room) 

as prescribed in the CDC TB Guidelines [CDC 2005b] and respiratory protection (at least an 

N95 particulate filtering facepiece respirator) should be used while performing procedures on 

these patients. 

While working to incorporate outdoor air into the occupied spaces at McDuff Campus, consideration should be given to optimizing air flow patterns to reduce the potential of airborne 

disease transmission between guests. The air flow pattern is important in any occupied 

space, but it is particularly important in the women’s overnight bunk area. These guests are 

not integrated into City Rescue Mission programs so their backgrounds and medical status may be unknown. While even the best ventilation system cannot guarantee preventing 

disease transmission between people in close proximity to one another, improving air flow 

patterns could help reduce the overall transmission potential among guests in each sleeping 

area. In the women’s overnight bunk area, one way that air flow patterns could be improved 

is to supply all air (fresh and recirculated) above the aisles between rows of beds using supply diffusers designed to discharge the air in a wide, downward deflected angle. At the same 

time, return grills should be installed low in the walls or in the ceiling along both outside 

walls of each space, parallel to the rows of beds. In this arrangement, supply air will generally pass over/across each bed and directly back to the AHU. This will reduce the potential 

of exhalations from one person passing through the breathing zone of multiple other people 

sharing the space. A qualified HVAC/ventilation engineer might recommend other air flow 

schemes that could be similarly effective at providing adequate ventilation while minimizing the potential for disease transmission. The final chosen design scheme should be smoke 

tested to verify performance.
Page 12 Health Hazard Evaluation Report 2012-0264-3182

We noticed additional issues affecting air flow patterns in other spaces as well. While a 

single supply vent and one return grille is appropriate in each of the family sleeping rooms, 

short-circuiting of air is a concern in these spaces as they are currently configured. As an example, Figure 3 shows the supply vent and return grille in the ceiling of family sleeping room 

#1. The close proximity of the supply to the return can easily result in short-circuiting of air, 

where supply air is immediately pulled into a return grille without providing any useful ventilation to room occupants. To alleviate this concern, the distance between the supply vent 

and return grille should be maximized to the extent possible. The other three family sleeping 

rooms had similar ventilation designs.

Several rooms in the men’s facility illustrated another issue, common in homeless shelters, 

that adversely affects air flow patterns and overall ventilation effectiveness. Figure 4 shows 

the supply vent in room #9 of the men’s facility covered with cardboard and tape. This is 

normally done for occupant comfort, but it clearly affects the ventilation air flow in room 

#9. However, it also affects ventilation air flow in surrounding areas since the air that would 

typically be delivered to room #9 is redirected elsewhere. This redirected air can help lead to 

occupant discomfort in surrounding spaces, which results in guests choosing to restrict supply air flow in their living spaces as well. Thus, the problem is compounded. This was the 

case in the men’s facility during our visit, as we noticed blocked or restricted supply vents in 

several other rooms in addition to room #9. Once updated ventilation systems are installed 

and balanced to introduce outdoor air into each space, restricting or blocking of supply vents 

and return grilles should be prohibited. If supply air blowing on room occupants is still an 

issue, supply vents designed to alter the air throw pattern while still providing the prescribed 

air flow could be chosen. 

We also noticed that several bathroom and shower exhaust fans were not operational during 

our visit (see Table 3). To control humidity and odors, bathrooms and shower areas should 

exhaust more air than the AHU is supplying. This will maintain these areas under negative 

pressure. Separate exhaust fans should be used to exhaust air directly outside at least 25 

feet from any air intakes, there should be no recycling or re-entrainment of return/exhaust 

air from the bathrooms and shower rooms. For high occupancy public bathrooms, 50 cfm 

of exhaust per toilet/urinal is recommended. For private toilets in bathrooms intended to be 

occupied by only one person at a time, ASHRAE 62.1-2010 specifies that the exhaust ventilation should be 25 cfm if the exhaust fan is designed to operate continuously (the Florida 

Building Code only requires 20 cfm) or 50 cfm if the exhaust fan only operates during periods of occupancy (e.g., exhaust fan controlled by a wall switch). All bathroom and shower 

exhaust fans should be made functional with their exhaust rates verified for compliance with 

the 2010 Florida Building Code, and they should be operational any time the rooms are occupied. [Note: The kitchen hood exhaust system was not evaluated at the time of the NIOSH 

site visit due to ongoing meal preparation activities. This exhaust was reportedly paired with 

its own makeup air system. Neither of these systems is discussed within this report.]

While not a major concern from an airborne disease transmission standpoint, temperature 

and relative humidity (RH) affect the perception of comfort in an indoor environment. The 

perception of thermal comfort is related to one’s metabolic heat production, the transfer of 
Health Hazard Evaluation Report 2012-0264-3182 Page 13

heat to the environment, physiological adjustments, and body temperature. Heat transfer 

from the body to the environment is influenced by factors such as temperature, humidity, air 

movement, personal activities, and clothing. ANSI/ASHRAE Standard 55-2010: Thermal 

Environmental Conditions for Human Occupancy specifies conditions in which 80% or more 

of the occupants are expected to find the environment thermally acceptable [ANSI/ASHRAE 

2010b]. Assuming slow air movement and 50% RH, the operative temperatures recommended by ASHRAE range from 68.5°F –76°F in the winter, and from 75.5°F – 80.5°F in the 

summer (see Table 4). The difference between the two temperature ranges is largely due to 

seasonal clothing selection. ASHRAE also recommends that RH be maintained at or below 

65%. The U.S. Environmental Protection Agency recommends maintaining indoor relative 

humidity between 30–50% because excessive humidity can promote the growth of microorganisms [EPA 2012]. Temperature and RH levels were not recorded during our visit because 

the main guest spaces were generally unoccupied. Regardless, we recommend maintaining 

the indoor temperature and RH levels within the ranges established by ASHRAE to provide 

the most comfortable environment to guests at McDuff Campus. Meeting the 30–50% RH 

recommendation would be significantly easier if a dedicated outdoor air system is installed to 

introduce conditioned outdoor air to the shelter, as explained above.

Respiratory Separation Areas

Currently, McDuff Campus does not have areas set aside for separating guests suspected of 

having TB or other respiratory diseases from the remainder of the guest population. Rapidly 

identifying people with suspected TB disease and keeping them separated from others until 

appropriate medical evaluations and treatments are initiated is one of the most important elements in reducing or eliminating the spread of airborne disease. The men and women enrolled in the LifeBuilders program are full-time residents of McDuff Campus, so their backgrounds and medical statuses are known. This is not necessarily the case for guests staying 

in the women’s overnight facility. Ideally, potential or suspect TB-positive cases would be 

identified during the intake screening process conducted at the New Life Inn, but, inevitably, 

some cases may slip through the screening process. As such, we strongly recommend identifying an area in the women’s overnight facility that can be used for respiratory separation 

when needed. It is important to recognize that respiratory separation is not an alternative to 

medical evaluation. Rather, it is proposed to be a temporary holding area for guests awaiting transport for medical evaluation. It may also be used to house guests exhibiting signs of 

respiratory distress without having disease. When respiratory separation is not required, the 

area can be used for normal guest housing or other purposes.

A respiratory separation area is not intended to be equivalent to an airborne infection isolation (AII) patient room found in hospitals and other healthcare settings. However, it can be 

designed using some of the same protective concepts, namely negative room pressure and 

elevated ventilation rates. The respiratory separation area should be maintained under negative pressure relative to the adjacent spaces. This means that air from outside the respiratory 

separation area should migrate inwards into the respiratory separation area and not in the 

opposite direction. This is easily maintained by exhausting more air from the respiratory 

separation area than is being supplied. Operable windows, either within the respiratory separation area or in adjacent areas, should not be allowed to interfere with this intent. Negative 
Page 14 Health Hazard Evaluation Report 2012-0264-3182

pressure helps reduce the potential that any guest housed in the respiratory separation area 

with active TB disease (or any other disease where airborne infection is a concern) could 

expose other healthy individuals in adjacent areas. In addition to maintaining negative pressure, all return air from the respiratory separation area should preferably be exhausted directly outside. In no circumstances should air from the respiratory separation area be allowed to 

re-infiltrate the building or go back through the AHU without first having passed through a 

high-efficiency particulate air (HEPA) filter.

For true AII rooms in healthcare facilities, the CDC and the FGI recommend a differential 

pressure of >0.01 inches of water gauge (2.5 Pascals [Pa]) across the closed door between 

the isolation area and adjacent areas [CDC 2005b; FGI 2010]. Although the minimum pressure difference needed for maintaining air flow into a room is quite small (about 0.001 inches 

of water gauge), the higher prescribed pressure differential is easier to measure and maintain 

as the pressure in surrounding areas changes due to the opening and closing of doors, ventilation system fluctuations, and other factors. The FGI and CDC also recommend a total of 12 

ACH through the isolation room (CDC allows 6 ACH for existing AII rooms) and at least 2 

ACH of fresh outdoor air. True AII rooms are designed to house individuals with confirmed 

respiratory disease. A respiratory separation area at McDuff Campus would not be used to 

house guests with confirmed disease, so it would not be necessary to meet the strict air flow 

and differential pressure requirements detailed above. However, knowledge of the AII design 

strategies could be useful in designing a respiratory separation area. It is vastly more important to establish a negative pressure area that can be used for respiratory separation than it is 

to focus on the respiratory separation area meeting quantitative ventilation requirements.

During our visit, we identified family sleeping rooms #3 and #4 as areas that might be converted to effective respiratory separation areas. At least one of these rooms should be upgraded to serve this purpose. All four of the family sleeping rooms receive and return air to 

AHU Women-2, and in addition to the family bathroom, the family sleeping rooms are the 

only areas served by AHU Women-2. One or more of these rooms could be converted for 

respiratory separation by 1) installing a solid, sealed ceiling in place of the existing drop ceiling or ensuring the walls for the selected room extend to the hard ceiling above the current 

drop ceiling, 2) installing a new exhaust fan through the outside wall of each selected room 

to provide the required exhaust air flow, and 3) installing tight-closing dampers (or some 

other mechanism) to completely seal all existing air returns from each selected room to AHU 

Women-2. Choose an exhaust fan that is capable of maintaining the room under negative 

pressure relative to the adjacent corridor with minimal noise. These fans could be mounted 

directly in the wall or on the roof with ductwork running through the wall and up to the fans 

on the outside of the women’s overnight facility. It is imperative that exhaust air from these 

new fans is directed away from all future AHU air intakes and gathering areas outside the 

building.

For the spaces selected for respiratory separation, the newly installed return air dampers 

should be sealed to prevent air from inside the room returning to AHU Women-2. The new 

exhaust fan should also be activated to maintain the space under negative pressure. For 

the majority of the time, when respiratory separation is not required, the room can be used 
Health Hazard Evaluation Report 2012-0264-3182 Page 15

as normal by shutting down the exhaust fan and reopening the return air dampers back to 

AHU Women-2. While it would be prudent to verify prior to any system renovations, AHU 

Women-2 should be able to self-balance if the return air grille from one of the suggested 

family sleeping rooms is blocked (when the room is used for respiratory separation). If not, 

additional ventilation modifications may be required to ensure that AHU Women-2 has an 

adequate supply of return air during periods when the rooms are simultaneously used for respiratory separation (and the normal return air paths from the rooms are blocked). To provide 

the AHU with the required return air flow, an alternative return air duct/damper system could 

be installed to pull air from an adjacent space. Care should be taken when choosing the alternative air return location so undesirable pressure relationships and air flow patterns do not 

result when the system is in operation.

For any respiratory separation area, a written plan for testing and operating the space is recommended. At McDuff Campus, a detailed written plan should be developed for the rapid 

conversion of the room from standard family sleeping area to use for respiratory separation. 

The plan should include contingency plans for moving the guests currently housed in the 

space to other locations, steps for cleaning and refurnishing the area for separation purposes, 

and step-by-step procedures for shelter staff to follow to effectively initiate respiratory separation.

All respiratory separation areas should be visually tested daily to ensure negative pressure 

is being maintained while the area is occupied for separation purposes. Testing can be done 

cheaply and easily with tissue flutter strips or smoke tubes. The results of the testing should 

be documented each day when in use. When the room is being used as a standard family 

sleeping room, it should be tested a minimum of once per month to ensure proper operation 

in the event it would be needed for respiratory separation.

Auxiliary HEPA Filtration

The higher the dilution ventilation rate within a given respiratory separation area, the faster 

the room air will be cleared of existing airborne pathogens. In order to increase effective 

ventilation within a separation area, in-room HEPA filtration units may be used. These units 

may be portable or permanently-mounted somewhere within the room. Some models can be 

ceiling mounted, which could reduce the potential for tampering. If such units are used, their 

placement and discharge orientation must be selected, installed, and maintained carefully to 

maximize room air mixing effectiveness without disrupting the desired flow of air into the 

respiratory separation area.

One unique use of portable HEPA filtration units is through ventilated headboards. The ventilated headboard is a NIOSH-developed technology that consists of lightweight, sturdy & 

adjustable aluminum framing with a retractable plastic canopy sheeting that can extend over 

the pillow area of a cot, mat or bed. Low-velocity airflow into the canopy is created using 

a high-efficiency fan/filter exhaust unit. This local control technique allows for near-instant 

capture of any aerosol originating from the patient while simultaneously providing air cleaning to the entire room. NIOSH engineers are available to provide additional information or 

to assist in the selection and acquisition of ventilated headboards.
Page 16 Health Hazard Evaluation Report 2012-0264-3182

Respiratory Protection

During an outbreak of airborne infectious disease, there could be instances when staff members or volunteers find themselves in close contact with guests suspected of being infectious. 

One example would be a van driver transporting overnight female guests to McDuff Campus from the City Rescue Mission sister shelter across town. Ideally, these cases would be 

identified during the administrative screening process. When these circumstances cannot be 

avoided, it is wise to consider the availability of respiratory protection to protect staff and 

volunteers. A particularly noteworthy circumstance would be a dentist providing urgent dental care to patients with suspected or confirmed TB disease in the McDuff dental clinic. In 

those instances, respiratory protection (at least an N95 particulate filtering facepiece respirator) should be worn by the dentist performing the procedures. 

The first step toward the implementation of respirator use is to develop a document that 

clearly outlines a formal respiratory protection program. The Occupational Safety and 

Health Administration (OSHA) Respiratory Protection standard (29 Code of Federal Regulations [CFR] 1910.134) outlines the requirements for comprehensive respiratory protection 

programs. In accordance with 29 CFR 1910.134, a written Respiratory Protection Program, 

with an identified program administrator, is required for any facility that requires employees 

to wear respirators. The program must include training, medical evaluations, and respirators at no cost to employees or staff required to wear respirators on the job. Initial fit testing 

by a trained individual is required for all employees that will potentially wear a respirator. 

Annual fit testing is required after that, with additional fit testing upon major changes to the 

facial features of the respirator user (i.e. major weight gain/loss, change in facial hair, scarring, etc.). 

To comply with applicable OSHA regulations regarding respiratory protection, we recommend that the shelter create a written respiratory protection program as outlined in 29 CFR 

1910.134, appoint a program administrator, and initiate training and initial fit testing for employees. Many online resources exist to assist in the development of a respiratory protection 

program. OSHA has published a Respiratory Protection informational booklet online (http://

www.osha.gov/Publications/OSHA3079/osha3079.html) and a more detailed Small Entity 

Compliance Guide for the Revised Respiratory Protection Standard (http://www.osha.gov/

Publications/3384small-entity-for-respiratory-protection-standard-rev.pdf) to explain all parts 

of an appropriate respiratory protection program and how to comply. The Small Entity Compliance Guide also contains a sample respiratory protection program in Attachment 4 that 

can be used as a model program. The Washington State Department of Labor and Industries 

has also developed a user-friendly, fillable template that is helpful in developing a respiratory 

protection program at http://www.lni.wa.gov/Safety/Basics/Programs/Accident/Samples/RespProtectguide2.doc.

The DCHD, Florida Department of Health, local healthcare facilities or fire/ambulance 

stations can potentially assist with training and fit testing the employees required to wear 

respirators. Alternatively, qualitative fit testing kits (BitrixTM) can be purchased for around 

$200.00. When paired with a trained and competent fit test administrator (see CFR 29 
Health Hazard Evaluation Report 2012-0264-3182 Page 17

1910.134), these kits would allow cost-effective, on-site fit testing annually.

Conclusions 

Since the increase in cases of TB disease in 2010, McDuff Campus has taken significant 

steps to improve the administrative controls at the shelter. The shelter has developed 

important lines of communication with DCHD, and improved staff training and awareness 

of TB symptoms. Identifying guests with symptoms of TB disease or those listed on 

the DCHD target screening lists will help further reduce the potential for future cases of 

TB disease and bring the ongoing outbreak under control. Having consistent protective 

strategies upon suspect case identification is also important. While enhanced administrative 

controls are now in place, there is no written ICP established at the complex, and McDuff 

Campus administrators are encouraged to promptly coordinate with DCHD and the Florida 

Department of Health to establish one. 

From an environmental control perspective, we inspected eight AHUs servicing the 

administration building, the women’s overnight sleeping facility, and the men’s facility. The 

preventive maintenance program in place is managed by the current facilities manager. The 

units appeared to be adequately maintained and were operational at the time of the NIOSH 

visit, although there were some with improper filter configurations and one containing 

standing water. There was no written preventive maintenance or O&M plan for the shelter 

AHUs. 

None of the AHUs at McDuff Campus were providing fresh outdoor air to the occupied 

spaces, as required by the 2010 Florida Building Code and ASHRAE guidelines. Given 

the number of guests served at the shelter complex and the close proximity of guests to 

one another in most of the occupied spaces, it is important that these spaces are receiving 

adequate amounts of outdoor air. In addition to alleviating odors and better maintaining 

occupant comfort, outdoor air serves to dilute infectious aerosols, such as M. tuberculosis

droplet nuclei responsible for TB transmission. With renovations, the existing AHUs 

might be made to provide the necessary outdoor air, or they could be augmented with the 

installation of new, dedicated outdoor air systems to provide the necessary outdoor air. A 

knowledgeable HVAC engineer should be consulted to discuss options for introducing 

outdoor air to the shelter complex. At the same time, consideration should be given 

to improving the air flow patterns in various living and sleeping areas throughout the 

complex. Once these changes have been implemented, other ventilation equipment and/or 

supplemental ultraviolet germicidal irradiation systems could be investigated if additional 

environmental controls are desired.

During our visit, McDuff Campus did not have an area set aside for separating guests 

suspected of having TB or other respiratory diseases from the remainder of the guest 

population. While this may not be critical in areas housing the men and women enrolled 

in the LifeBuilders program, the background and medical status of every woman seeking 

overnight shelter in the women’s overnight facility is unknown. Therefore, it would 

be prudent to modify an area in the women’s overnight facility for use as a respiratory 
Page 18 Health Hazard Evaluation Report 2012-0264-3182

separation area in the event an overnight guest presented with symptoms of respiratory 

infection. When respiratory separation is not required, the area could be used for normal 

guest housing. 

For instances where improvements to administrative and environmental controls do not 

sufficiently mitigate the risk for disease transmission, respiratory protection might be 

necessary. There was no formal respiratory protection program in place during our visit, 

but such a program should be implemented at the shelter. Having this program in place 

will provide additional protection to McDuff Campus staff and volunteers working in close 

proximity to guests with suspected TB or other airborne diseases. Any respirator use at the 

shelter should be covered by an OSHA-mandated respiratory protection program.

Administratively, a positive approach is being taken toward reducing the likelihood of future 

TB transmission at McDuff Campus. However, the ventilation systems clearly need some 

attention to further reduce the risk. While ventilation systems and other environmental 

control systems cannot guarantee prevention of future TB disease transmission, improving 

the environmental controls will reduce the potential for airborne disease transmission, 

along with providing better indoor air quality throughout each building. The following 

recommendations are aimed at improving the overall infection control program at McDuff 

Campus, with emphasis on improvements to the existing environmental controls so they meet 

all applicable standards and guidelines.

Recommendations 

Based on our assessment of environmental controls at McDuff Campus, we have developed 

the following list of recommendations, in order of priority:

1. Continue to improve and enhance the TB administrative controls at the complex and 

develop a written Infection Control Plan.

● Continue working with the DCHD to screen campus staff, volunteers, and 

guests for TB disease.

● With input from DCHD, develop specific procedures for handling a suspected 

or confirmed case of TB disease.

● Continue educating staff and volunteers on the signs and symptoms of TB 

disease so they can readily identify suspect cases and implement established 

precautions.

● Consider displaying informational posters about TB signs and symptoms to 

educate guests.

● Consider displaying signs encouraging proper cough etiquette and hand 

hygiene.
Health Hazard Evaluation Report 2012-0264-3182 Page 19

● Develop a formal written TB Infection Control Plan. Seek guidance and input 

from DCHD and the Florida Department of Health. The plan should include:

○ All aspects of the TB infection control program and associated 

responsibilities, especially those functions requiring coordination with 

other agencies, such as the local and state health departments

○ The improved administrative controls put in place at McDuff Campus 

since the beginning of the TB outbreak

○ Input from ventilation staff and/or guests tasked with servicing 

ventilation systems. Obtaining input from ventilation maintenance 

staff serves to strengthen the environmental control section of the plan 

while giving maintenance staff additional insight into the ventilation 

requirements for reducing or preventing airborne disease transmission.

○ Schedule for updating and revising the ICP

2. Introduce the required amounts of fresh outdoor air to all occupied spaces.

● There are multiple options that can allow adequate outdoor air to be supplied 

to the various campus buildings. All options, including the associated capital, 

maintenance, and annual operating costs should be considered. Work with 

a reputable ventilation or engineering contractor familiar with the current 

Florida Building Code, ASHRAE, FGI, and CDC guidelines to select the best 

option for McDuff Campus.

● Improve air flow patterns within all occupied spaces, particularly the women’s 

overnight bunk area and family sleeping rooms. Air flow patterns should 

provide effective ventilation and temperature control while minimizing the 

number of people that air travels across before returning to the AHU. 

● Determine and fix the cause of the standing water inside AHU Men-2. 

Develop a monitoring strategy to prevent further occurrences of water buildup 

within the unit. 

3. Improve filtration efficiency in all AHUs. Select higher efficiency filters (higher 

MERV ratings) for use in each AHU, as long as the new filters do not adversely 

impact the required air flow delivery capacity of the AHUs. 

4. Modify at least one family sleeping room in the women’s overnight facility for use as 

a respiratory separation area.

•	 Choose a reputable ventilation or engineering design contractor that is familiar 

with current Florida Building Code, ASHRAE, FGI, and CDC guidelines 

and recommendations. While there are various ways to develop a respiratory 
Page 20 Health Hazard Evaluation Report 2012-0264-3182

separation area, it should include the following:

○ Ensure that all supply and return ductwork for AHU Women-2 is intact 

and sealed. Install tight-sealing return dampers on each return from 

the selected family sleeping room to eliminate return air flow when 

the space is used for respiratory separation. Ensure that supply air 

diffusers provide good air mixing and air flow patterns in each selected 

room.

○ Design and install an auxiliary exhaust system that enables the 

respiratory separation area to be maintained under negative pressure 

when housing guests for separation purposes. One approach to this 

requirement would be to select and install an exhaust fan directly 

through the outside walls of the room. The fan can be mounted 

through the wall itself or mounted on the roof with ductwork through 

the wall to the fan.

○ Install the highest efficiency air filters in AHU Women-2 that will still 

allow adequate air flow to meet the AHU’s conditioning requirements. 

Adjust and balance the system as necessary to ensure proper air flows 

at all times when each selected room is individually or collectively 

used for respiratory separation and normal purposes. Ensure that 

adequate outdoor air is supplied to each space at all times (see 

Recommendation 2 above).

○ Develop a detailed written plan for the conversion of the selected 

family sleeping room(s) from normal housing functions to use for 

respiratory separation. The plan should include:

▪ Procedures for moving the guests currently in these areas to 

other locations

▪ Procedures for cleaning and refurnishing the areas for 

separation purposes, and step-by-step procedures for staff to 

follow to start the exhaust fan, close the return air dampers, and 

test for negative pressure

▪ Measures for preparing the areas for back-to-back occupants 

requiring separation

▪ Procedures for cleaning and returning the areas to normal use 

after the need for respiratory separation has passed

○ Operate the new systems as designed and according to the written 

plan. The respiratory separation area should be visually tested with 

smoke tubes or flutter strips daily to ensure negative pressure is being 

maintained while the room is occupied for separation. When the 

room is being used for normal purposes, it should be tested monthly 

to ensure proper operation in the event they would be needed for 
Health Hazard Evaluation Report 2012-0264-3182 Page 21

respiratory separation. The results of all pressure testing should be 

documented.

5. Ensure the dental clinic is ventilated appropriately. The clinic should be provided 

with at least 6 total air changes per hour (ACH) and at least 2 ACH of fresh outdoor 

air. Additionally, if one does not already exist, an exhaust fan should be installed to 

maintain the clinical space under negative pressure any time dental procedures are 

being performed. If nitrous oxide is used as an analgesic/anesthetic gas in this clinic, 

NIOSH engineers can provide additional guidance on special design precautions that 

apply to its safe storage, delivery and recovery upon request.

6. Develop and implement an OSHA respiratory protection program in accordance with 

29 CFR 1910.134. To meet the OSHA requirements, you must:

● Designate a program administrator who is qualified by appropriate training 

or experience to administer or oversee the program and conduct the required 

program evaluations.

● Provide respirators, training, and medical evaluations at no cost to employees 

or staff required to wear respirators on the job.

● Develop a written program with worksite-specific procedures when respirators 

are necessary or required by McDuff Campus. The written respiratory 

protection program needs to include:

○ Respirator types and proper respirator selection

○ Required medical evaluations for employees prior to respirator use

○ Procedures for initial and annual respirator fit testing

○ Instructions for proper respirator use

○ Information on appropriate respirator maintenance and care

○ Initial and yearly training requirements for respirator users 

○ Procedures for evaluating the effectiveness of the respiratory 

protection program

● Update the respiratory protection program as necessary to reflect changes in 

workplace conditions that affect respirator use.

7. Repair existing bathroom exhaust fans or install new ones. Ensure that air is being 

exhausted from each bathroom and shower facility and that each area is under 
Page 22 Health Hazard Evaluation Report 2012-0264-3182

negative pressure, in accordance with the 2010 Florida Building Code and ASHRAE 

requirements. Ensure that all exhaust air from bathrooms and shower facilities is 

exhausted directly outside and that no return air from bathrooms is recirculated back 

to an AHU or entrained in the outdoor air entering any current or future AHU.

8. After all of the ventilation systems are updated and functioning properly, develop a 

comprehensive, written HVAC O&M plan. The O&M Plan should include:

● Preventive maintenance schedules and all regularly scheduled maintenance 

tasks (filter changes, fan belt inspections, etc.) and who is responsible for 

conducting each task

● Written procedures for each maintenance task to ensure the work is done 

properly each time, regardless of who performs the work

● Training requirements for maintenance staff

● A method for logging maintenance activities for each AHU

● A method for updating or revising the O&M Plan as procedures or systems 

change

Outline of Future NIOSH Involvement

This report will serve to close out NIOSH Technical Assistance at McDuff Campus. 

However, we understand that the work outlined in the recommendations above will take 

several months to complete and will represent a significant investment of time and financial 

resources. As the work proceeds, NIOSH could assist by:

● Reviewing any Requests for Proposal developed to initiate the bidding process 

● Reviewing any bids received in response to Requests for Proposals for 

technical content

● Providing technical assistance related to any environmental control strategies

It is not necessary for NIOSH to be on-site during any ventilation renovations. Yet, as 

projects are initiated, we can assist you by reviewing:

● Proposed modification strategies for outdoor air introduction or respiratory 

separation area designs

● Preliminary design schematics or equipment selection documents

● Air flow testing and balancing reports
Health Hazard Evaluation Report 2012-0264-3182 Page 23

● Final project documents, including as-built drawings, sequences of operations, 

and proper equipment set points

Once the renovations are complete, if additional NIOSH assistance is desired or warranted, 

the request for technical assistance can be reopened.
Page 24 Health Hazard Evaluation Report 2012-0264-3182

References

ANSI/ASHRAE (American National Standards Institute/American Society of Heating, Ventilating and Air-Conditioning Engineers) [2007]. Method of testing general ventilation aircleaning devices for removal efficiency by particle size. Atlanta, GA: American Society 

of Heating, Refrigerating and Air-Conditioning Engineers. Standard 52.2-2007.

ANSI/ASHRAE [2010a]. Ventilation for acceptable indoor air quality. Atlanta, GA: American Society of Heating, Refrigerating and Air-Conditioning Engineers. Standard 62.1-

2010. 

ANSI/ASHRAE [2010b]. Thermal environmental conditions for human occupancy. Atlanta, 

GA: American Society of Heating, Refrigerating and Air-Conditioning Engineers. Standard 55-2010.

ASHRAE/ASHE (ASHRAE/American Society for Healthcare Engineering) [2008]. Ventilation of health care facilities. Atlanta, GA: American Society of Heating, Refrigerating 

and Air-Conditioning Engineers. Standard 170-2008.

Barry MA, Wall C, Shirley L, Bernardo J, Schwingl P, Brigandi E, Lamb GA [1986]. Tuberculosis screening in Boston’s homeless shelters. Public Health Rep 101(5):487-498.

CDC (Centers for Disease Control and Prevention) [1985]. Drug-resistant tuberculosis 

among the homeless—Boston. MMWR 34:429-431.

CDC [1992]. Prevention and control of tuberculosis among homeless persons (ACET). 

MMWR 41(RR-5):001.

CDC [2003a]. Tuberculosis outbreak in a homeless population—Portland, Maine, 2002-2003. 

MMWR 52(48):1184-1185.

CDC [2003b]. TB outbreak among homeless persons—King County, Washington, 2002-

2003. MMWR 52(49):1209-1210.

CDC [2005a]. Tuberculosis transmission in a homeless shelter population—New York, 2000-

2003. MMWR 54(06):149-152.

CDC [2005b]. Guidelines for preventing the transmission of Mycobacterium tuberculosis in 

health-care settings, 2005. MMWR 54(RR-17):1-141.

CDC [2006]. Prevention and control of tuberculosis in correctional and detention facilities: 

Recommendations from CDC. MMWR 55(RR-9):1-54.

EPA (US Environmental Protection Agency) [2012]. The inside story: A guide to indoor air 

quality (http://www.epa.gov/iaq/pubs/insidestory.html). Date accessed: February 22, 

2013.
Health Hazard Evaluation Report 2012-0264-3182 Page 25

FGI (Facility Guidelines Institute) [2010]. Guidelines for design and construction of health 

care facilities. Chicago, IL: American Society for Healthcare Engineering of the American Hospital Association.

Flanders Corporation [2011]. Pre Pleat 40 LPD low pressure drop MERV 8 pleated filter, 

product bulletin PB700-1211.

ICC (International Code Council, Inc.) [2011]. Florida building code 2010: Mechanical 

(chapter 4, ventilation). Country Club Hills, IL: International Code Council, Inc.

Knopf SA [1914]. Tuberculosis as a cause and result of poverty. J Am Med Assoc 

63(20):1720-1725.

McAdam JM, Brickner PW, Scharer LL, Crocco JA, Duff AE [1990]. The spectrum of tuberculosis in a New York City men’s shelter clinic (1982-1988). Chest 97:798-805.

NIOSH [2013]. NIOSH alert: preventing occupational respiratory disease from exposures 

caused by dampness in office buildings, schools, and other non-industrial buildings. By 

Martin M, Cox-Ganser J, Kreiss K, Kanwal R, Sahakian N. Cincinnati, OH: U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, 

National Institute for Occupational Safety and Health, DHHS (NIOSH) Publication No. 

2013-102 (http://www.cdc.gov/niosh/docs/2013-102/pdfs/2013-102.pdf). Date accessed: 

February 22, 2013. 

Nolan CM, Elarth AM, Barr H, Saeed AM, Risser DR [1991]. An outbreak of tuberculosis 

in a shelter for homeless men: A description of its evolution and control. Am Rev Respir 

Dis 143:257-261.

Slutkin G [1986]. Management of tuberculosis in urban homeless indigents. Public Health 

Rep 101(5):481-485.
Page 26 Health Hazard Evaluation Report 2012-0264-3182 Table 1. General air-handling unit (AHU) information NIOSH AHU Identifier Physical Location of AHU (building/floor) Location Served by AHUA AHU ManufacturerB AHU Model NumberB Proper Filter Configuration in AHUC,D Actual Filter Configuration in AHUB,D,E AHU-1 Central Mechanical Room (Administration Building/1st Floor) Entire 1st Floor of Administration Building Carrier 40RR034 (6) 20 × 25 × 2 and (2) 16 × 20 × 2 *(8) 20 × 25 × 2 AHU-2 Central Mechanical Room (Administration Building/3rd Floor) Entire 2nd Floor of Administration Building Carrier 40RR028 (6) 20 × 25 × 2 and (2) 16 × 20 × 2 *(12) 16 × 20 × 2 AHU-3 Central Mechanical Room (Administration Building/4th Floor) Entire 3rd Floor of Administration Building Carrier 40RR028 (6) 20 × 25 × 2 and (2) 16 × 20 × 2 *(12) 16 × 20 × 2 AHU-4 Central Mechanical Room (Administration Building/4th Floor) Entire 4th Floor of Administration Building Carrier 40RR028 (6) 20 × 25 × 2 and (2) 16 × 20 × 2 *(12) 16 × 20 × 2 Women-1 Women’s Overnight Facility - Above Laundry Room Women’s Overnight Bunk Areas Trane TWE090A300EL (3) 16 × 25 × 1 GrilleF Women-2 Women’s Overnight Facility - Above Family Bathroom & Showers Women’s Overnight Family Areas Trane TWE042C14FCD (1) 20 × 20 × 1 GrilleF Men-1 Men’s Facility - Mechanical Room Beside Shower Room in Hallway 2 Men’s Facility - Rooms off Hallways 1 and 2 Trane TWE090A300CA (3) 16 × 25 × 1 (3) 16 × 25 × 1 Men-2 Men’s Facility - Outside Main Entrance to Men’s Facility Men’s Facility - Rooms off Hallways 3 and 4 Carrier UnknownG UnknownG (6) 16 × 20 × 2 A May not represent all locations served by the AHU B Information taken during visual inspection of AHU C Information gathered from product data specific to each AHU model published by respective AHU manufacturer D Value in parenthesis represents the number of filters, dimensions are width × height × depth in units of inches E Entries preceded by an asterisk (*) represent actual filter configurations that differ from published proper filter configurations. Differences could be due to incorrect filter size(s) being installed or because the AHU manufacturer modified the AHU model size/filter recommendation as the product was updated. F It could not safely be determined if filters were installed in these AHUs during the NIOSH visit. However, return air filters were in place at each return air grille into the ceiling plenum. G Labels and stickers on this AHU were missing or faded, so they could not be read.

Tables
Health Hazard Evaluation Report 2012-0264-3182 Page 27 Table 2. Applicable outdoor air supply flow rates, minimum exhaust air flow rates, and default occupancy densities from the 2010 Florida Building Code and ASHRAE Standard 62.1-2010A Occupancy Category People Outdoor Air Flow Rate (cfm/person)B Area Outdoor Air Flow Rate (cfm/ft2)C Minimum Exhaust Air Flow RateD Default Occupant Density (#/1000 ft2)E Barracks/Dormitory Sleeping Areas 5 0.06 — 20 Bedrooms/Living Rooms 5 0.06 — 10 Office Spaces 5 0.06 — 5 Conference Rooms 5 0.06 — 50 Multipurpose Assembly Spaces 5 0.06 — 120 Reception Areas 5 0.06 — 30 Break RoomsF 5F 0.12F — 50F Central Laundry RoomsF 5F 0.12F — 10F Occupiable Dry Storage RoomsF 5F 0.06F — 2F Occupiable Liquid/Gel Storage RoomsF 5F 0.12F — 2F Unoccupiable Storage RoomsG — 0.12G — — Lobbies/Prefunction Spaces 7.5 0.06 — 30 Lecture Classrooms 7.5 0.06 — 65 Computer Labs 10 0.12 — 25 Dining Rooms 7.5 0.18 — 70 Central Kitchens 7.5F 0.12F 0.7 cfm/ft2 C 70 Public Bathrooms — — 50 or 70 cfm/toilet and/or urinalH — Private Bathrooms — — 25 or 50 cfmI — Shower RoomsG — — 20 or 50 cfm/shower headG,J — A Requirements published in: 2010 Florida Building Code: Mechanical (Chapter 4, Ventilation). International Code Council, Inc., Country Club Hills, IL (2011) and American National Standards Institute (ANSI)/American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE). Ventilation for Acceptable Indoor Air Quality, Standard 62.1- 2010. ASHRAE, Atlanta, GA (2010). In nearly all cases, the 2010 Florida Building Code has adopted ventilation recommendations directly from ASHRAE Standard 62.1-2010. B cfm/person = cubic feet per minute (also commonly shown as ft3/min) per person typically in the occupied space C cfm/ft2 = cubic feet per minute (also commonly shown as ft3/min) per square feet of occupied space D Mechanical exhaust should be released directly outdoors at least 25 feet away from air intakes. Recirculation of exhaust air back into the building should be avoided. E #/1000ft2 = number of people per 1000 square feet of occupied space. These values are typical occupant densities in spaces that are useful for building/HVAC system design. If actual occupant densities are known, they should be used instead of these default values. F Requirements are only published in ASHRAE Standard 62.1-2010. No directly corresponding values appear in the 2010 Florida Building Code. G Requirements are only published in the 2010 Florida Building Code. No directly corresponding values appear in ASHRAE Standard 62.1-2010. H Provide the higher rate when periods of heavy use are expected to occur (e.g. prior to guests leaving in the morning). If periods of heavy use are not anticipated, the lower rate may be used.

I These rates are for bathrooms intended for use by one person at a time. If exhaust fans are operated continuously, the lower rate may be used. If exhaust fans are operated  intermittently (e.g., fans activated by a light switch), the higher rate should be used.J If exhaust fans are operated continuously, the lower rate may be used. If exhaust fans are operated intermittently (e.g., fans activated by a light switch), the higher rate should be  used.
Page 28 Health Hazard Evaluation Report 2012-0264-3182 Table 3. Total air delivered by ventilation systems, occupant densities, and recommended outdoor air flow SpaceA AHU Serving Space Return Flow from Space (cfm)B Supply Flow into Space (cfm)B Approximate Area of Space (ft2)C Typical Occupants in SpaceD Occupant Density (#/1000 ft2)D,E,F Recommended Outdoor Air Flow (cfm)B,G 1st Floor – Main Administration Building Assembly/Dining Room AHU-1 550 3265 2980 60 20 478.8/968.4H Hospitality Room AHU-1 0I 585 790 12 15 107.4 Medical - Reception AHU-1 NoneJ 230 195 2 10 21.7 Medical - Exam Room 1K,L AHU-1 NoneJ 70 90 2 22 15.4 Medical - Exam Room 2K,L AHU-1 <30I 350 125 2 16 17.5 Medical - Supply StorageK AHU-1 NoneJ 315 255 0 0 30.6 Medical - Laboratory N/A NoneJ NoneM 85 1 12 10.1 3nd Floor – Main Administration Building Room F1 AHU-3 NoneJ <60I,N 195 2 10 21.7 Room F2 AHU-3 NoneJ 250 195 2 10 21.7 Room F3 AHU-3 NoneJ 295 195 2 10 21.7 Sitting Area off Room F3 N/A NoneJ NoneM 80 2 *25 14.8 Room F4 AHU-3 NoneJ 170 195 2 10 21.7 Room F5 AHU-3 NoneJ 400 195 2 10 21.7 Room F6 AHU-3 NoneJ 220 195 2 10 21.7 Phoebe Room AHU-3 NoneJ 340 195 2 10 21.7 Room F8 AHU-3 NoneJ 210 195 2 10 21.7 Room F9 AHU-3 NoneJ 340 195 2 10 21.7 Room F10 AHU-3 NoneJ 340 195 2 10 21.7 Sitting Area off Room F10 N/A NoneJ NoneM 80 2 *25 14.8 Room F11 AHU-3 NoneJ 255 190 2 11 21.4 Room F12 AHU-3 NoneJ 210 185 2 11 21.1 Room S1 AHU-3 NoneJ 705 600 2 3 46.0 Room S2 AHU-3 NoneJ 500 585 2 3 45.1 Room S3 AHU-3 NoneJ 520 590 2 3 45.4 Room S4 AHU-3 NoneJ 635 590 2 3 45.4

Priscilla Powder Room N/A <30I,O NoneM 90 N/AP N/AP N/AP
Health Hazard Evaluation Report 2012-0264-3182 Page 29 Table 3 (continued). Total air delivered by ventilation systems, occupant densities, and recommended outdoor air flow SpaceA AHU Serving Space Return Flow from Space (cfm)B Supply Flow into Space (cfm)B Approximate Area of Space (ft2)C Typical Occupants in SpaceD Occupant Density (#/1000 ft2)D,E,F Recommended Outdoor Air Flow (cfm)B,G Fellowship Room AHU-3 NoneJ 940 685 3 4 56.1 Laundry Room AHU-3 NoneJ 400 130 1 8 20.6 Shower Room N/A ObsQ NoneM 80 N/AP N/AP N/AP Bathroom N/A ObsQ NoneM 80 N/AP N/AP N/AP Exercise Room AHU-3 NoneJ 780 600 1 2 92.0 RA Office AHU-3 NoneJ 400 185 1 5 27.2 Women’s Clothing Room off RA Office AHU-3 NoneJ 400 380 1 3 50.6 4th Floor – Main Administration Building Room 435 AHU-4 NoneJ 765 570 10 18 109.2 Room 441 AHU-4 NoneJ 635 590 10 17 110.4 Room 443 AHU-4 NoneJ 670 585 10 17 110.1 Room 445 AHU-4 NoneJ 750 600 10 17 111.0 Large Computer Room AHU-4 NoneJ 550 590 10 17 170.8 Small Computer Room AHU-4 NoneJ 80 145 2 14 37.4 Library AHU-4 NoneJ 210 175 2 11 31.0 Women’s Overnight Facility Overnight Bunk Area/Reception/Entry Women-1 2125 1705 1865 42 *23 321.9 Overnight Bathroom & Showers Women-1 0I 270 325 N/AP N/AP N/AP Family Sleeping Room #1 Women-2 40 205 130 3 *23 7.8 Family Sleeping Room #2 Women-2 0I 230 130 3 *23 22.8 Family Sleeping Room #3 Women-2 0I 170 130 3 *23 22.8 Family Sleeping Room #4 Women-2 35 220 130 3 *23 22.8 Family Area Hallways Women-2 1055 210 160 0 0 19.2 Family Bathroom & Showers Women-2 0I 270 195 N/AP N/AP N/AP
Page 30 Health Hazard Evaluation Report 2012-0264-3182 Table 3 (continued). Total air delivered by ventilation systems, occupant densities, and recommended outdoor air flow SpaceA AHU Serving Space Return Flow from Space (cfm)B Supply Flow into Space (cfm)B Approximate Area of Space (ft2)C Typical Occupants in SpaceD Occupant Density (#/1000 ft2)D,E,F Recommended Outdoor Air Flow (cfm)B,G Men’s Facility Bedroom 1 Men-1 NoneJ 75 145 2 14 18.7 Bedroom 2 Men-1 NoneJ 115 145 2 14 18.7 Bedroom 3 Men-1 NoneJ 60 145 2 14 18.7 Bedroom 4 Men-1 NoneJ 160 135 2 14 18.1 Bedroom 5 Men-1 NoneJ 40R 145 2 14 18.7 Bedroom 6 Men-1 NoneJ 60R 145 2 14 18.7 Bedroom 7 Men-1 NoneJ 230 145 2 14 18.7 Hallway 1 Bathroom Men-1 0I 110 155 N/AP N/AP N/AP Bedroom 8 Men-1 NoneJ 85 145 2 14 18.7 Bedroom 9 Men-1 NoneJ 0I,R 145 2 14 18.7 Bedroom 10 Men-1 NoneJ ObsS 145 2 14 18.7 Bedroom 11 Men-1 NoneJ 70 145 2 14 18.7 Bedroom 12 Men-1 NoneJ 70 145 2 14 18.7 Bedroom 13 Men-1 NoneJ 160 145 2 14 18.7 Hallway 2 Prayer Room Men-1 NoneJ 70 90 1 11 10.4 Hallway 2 Shower Room Men-1 0I 130 155 N/AP N/AP N/AP Recreation Room UnknownT NoneJ 325 520 2 4 41.2 Bedroom 14 Men-2 NoneJ 115 215 2 9 22.9 Bedroom 15 Men-2 <30I ObsS 215 2 9 22.9 Bedroom 16 Men-2 0I 215 235 2 9 24.1 Lounge Between Hallways 3 & 4 Men-2 760 260 535 2 4 42.1 Hallway 3 Bathroom N/A NoneJ NoneM DNMU N/AP N/AP N/AP Bedroom 17 Men-2 0I ObsS 155 2 13 19.3 Bedroom 18 Men-2 0I ObsS 155 2 13 19.3 Bedroom 19 Men-2 0I 120 155 2 13 19.3
Health Hazard Evaluation Report 2012-0264-3182 Page 31 Table 3 (continued). Total air delivered by ventilation systems, occupant densities, and recommended outdoor air flow SpaceA AHU Serving Space Return Flow from Space (cfm)B Supply Flow into Space (cfm)B Approximate Area of Space (ft2)C Typical Occupants in SpaceD Occupant Density (#/1000 ft2)D,E,F Recommended Outdoor Air Flow (cfm)B,G Bedroom 20 Men-2 0I 175 150 2 13 19.0 Bedroom 21 Men-2 NoneJ 140 205 2 10 22.3 Bedroom 22 Men-2 NoneJ 85 205 2 10 22.3 Bedroom 23 Men-2 NoneJ 65 205 2 10 22.3 Hallway 4 Bathroom N/A NoneJ NoneM 200 N/AP N/AP N/AP Weight Room N/A NoneJ NoneM 340 1 3 60.8 A May not represent all locations served by the AHU B cfm= cubic feet per minute (also commonly shown as ft3/min) C ft2 = square feet D Occupant numbers estimated by visual observation during NIOSH visit E #/1000 ft2 = number of occupants per 1000 ft2 of occupied floor space. Calculated by dividing the number of typical occupants in the space by the approximate area of the space and multiplying by 1000 F Entries preceded by an asterisk (*) represent spaces where the actual occupant density likely exceeds the default occupant density presented in Table 2. G Calculated based on recommendations published in: American National Standards Institute (ANSI)/American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE). Ventilation for Acceptable Indoor Air Quality, Standard 62.1-2010. ASHRAE, Atlanta, GA (2010) and the 2010 Florida Building Code: Mechanical (Chapter 4, Ventilation). International Code Council, Inc., Country Club Hills, IL (2011). In nearly all cases, the 2010 Florida Building Code has adopted ventilation recommendations directly from ASHRAE Standard 62.1-2010. H ASHRAE Standard 62.1-2010 and the 2010 Florida Building Code: Mechanical (Chapter 4, Ventilation) provide separate outdoor air recommendations for assembly spaces and dining rooms. Both numbers are reported here (assembly space/dining area). I A TSI Accubalance Plus, Model 8373, was used to determine air flow measurements. The instrument is unable to accurately read volumetric air flow rates less than 30 cfm. Reading could be anywhere between 0 and 30 cfm. In these cases, ventilation fog was used to visually determine if any air was flowing through the vent/grille. When there was visual confirmation of air flow, the result was reported as < 30 cfm. When air flow could not be verified visually, the result was reported as 0 cfm. J There was/were no return grille(s) in this space. K A partial wall exists between the two medical exam rooms and the medical storage space, so these areas could be considered one space. They were left separate in this table because of their functions. L Areas where medical examinations and/or procedures are performed should be maintained under negative pressure compared to adjacent areas (i.e., more air should be exhausted from the space than is supplied to the space). This space was not under negative pressure during the NIOSH visit. M There was/were no supply vent(s) in this space. N There were two supply vents in this space. Visually, both appeared to be supplying air but less than the TSI Accubalance Plus, Model 8373 could measure (see Footnote I). O This area was equipped with a switch activated exhaust fan designed for intermittent use when the space is occupied. P N/A = not applicable. Neither ASHRAE Standard 62.1-2010 nor the 2010 Florida Building Code include outdoor air recommendations for restrooms, bathrooms, and shower facili ties. Instead, for public bathrooms, the recommendation is 50 cfm of exhaust from the space per toilet or urinal when periods of heavy use are not expected. ASHRAE 62.1-2010 does not specifically address ventilation for showers. However, the 2010 Florida Building Code: Mechanical (Chapter 4, Ventilation) specifies 50 cfm of exhaust air from the space per shower head when the exhaust system is designed to operate intermittently (e.g., exhaust fan connected to light switch) or 20 cfm per shower head for exhaust systems designed to operate continuously. Water closet and shower exhaust may be made up entirely of transfer air from adjacent spaces (i.e., no direct supply air to the space is required) and only a maximum of 10% of the exhaust air is permitted to be recycled. Q Obs = obstructed. Air flow measurements could not be taken because the exhaust grille(s) were obstructed. Exhausts were determined to be working via ventilation fog testing. R Cardboard was covering or partially covering the supply vent. The cardboard was not removed during the NIOSH visit. S Obs = obstructed. Air flow measurements could not be taken because the supply vent(s) were obstructed by furniture, storage boxes, shelves, etc. T It was not determined which AHU(s) in the Men’s Facility supplied air to the recreation room.

U DNM = did not measure. Physical dimensions were not recorded for this space.
Page 32 Health Hazard Evaluation Report 2012-0264-3182

Table 4. ASHRAE indoor relative humidity and temperature recommendationsA

Relative Humidity Winter TemperaturesB Summer TemperaturesB

30%C 69.5°F to 77.0°F 75.5°F to 81.5°F

40% 69.0°F to 76.5°F 75.5°F to 81.0°F

50%D 68.5°F to 76.0°F 75.0°F to 80.5°F

A Adapted from: American National Standards Institute (ANSI)/American Society of Heating, Refrigerating and Air- 

 Conditioning Engineers (ASHRAE). Thermal Environmental Conditions for Human Occupancy, Standard 55-2010. 

 ASHRAE, Atlanta, GA. (2010)

B

 Applies to occupants wearing typical summer and winter clothing, with a sedentary to light activity level

C Humidity levels below 30% may cause irritated mucus membranes, dry eyes, and sinus discomfort.

D The U.S. Environmental Protection Agency recommends maintaining indoor relative humidity below 60% and ideally 

 in a range from 30% to 50% to prevent mold growth.
Health Hazard Evaluation Report 2012-0264-3182 Page 33

Figure 1. Return air grille leading to the AHU serving the women’s overnight bunk area 

(Women-1). Air flow from the fan creates significant filter bypass.

Figures
Page 34 Health Hazard Evaluation Report 2012-0264-3182

Figure 2. Standing water and apparent microbial growth in the drain pan of AHU Men-2.
Health Hazard Evaluation Report 2012-0264-3182 Page 35

Figure 3. Supply vent and return grille in ceiling of family sleeping room #1 in the 

women’s overnight facility. The close proximity of the supply to the return can result in 

short-circuiting of air, where supply air is immediately pulled into a return grille without 

providing any useful ventilation.
Page 36 Health Hazard Evaluation Report 2012-0264-3182

Figure 4. Supply vent covered with cardboard and tape in room #9 of the men’s sleeping 

area.
Health Hazard Evaluation Report 2012-0264-3182 Page 37

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Page 38 Health Hazard Evaluation Report 2012-0264-3182

The Health Hazard Evaluation Program investigates possible health hazards in the 

workplace under the authority of Section 20(a)(6) of the Occupational Safety and 

Health Act of 1970, 29 U.S.C. 669(a)(6). The Health Hazard Evaluation Program also 

provides, upon request, technical assistance to federal, state, and local agencies to control 

occupational health hazards and to prevent occupational illness and disease. Regulations 

guiding the Program can be found in Title 42, Code of Federal Regulations, Part 85; 

Requests for Health Hazard Evaluations (42 CFR 85).

Acknowledgments

This report was prepared by Stephen B. Martin, Jr., R. Brent Lawrence, and Michael C. 

Beaty of the Field Studies Branch (FSB), Division of Respiratory Disease Studies (DRDS) 

and Kenneth R. Mead of the Engineering and Physical Hazards Branch, Division of Applied 

Research and Technology. Desktop publishing was performed by Tia McClelland (FSB/

DRDS).

Availability of Report

Copies of this report have been sent to representatives from City Rescue Mission–New Life 

Inn, DCHD, the Florida Department of Health, CDC/NCHHSTP/DTBE, and the OSHA

Regional Office. This report is not copyrighted and may be freely reproduced. 

This report is available at http://www.cdc.gov/niosh/hhe/reports/pdfs/2012-0264-3182.pdf.

Recommended citation for this report:

NIOSH [2013]. Health hazard evaluation report: Evaluation of 

environmental controls at a homeless shelter complex (City Rescue 

Mission–McDuff Campus) associated with a tuberculosis outbreak – 

Florida. By Martin, Jr. SB, Mead KR, Lawrence RB, Beaty MC. Morgantown, 

WV: U.S. Department of Health and Human Services, Centers for Disease 

Control and Prevention, National Institute for Occupational Safety and 

Health, NIOSH Report No. 2012-0264-3182.
To receive documents or other information about

occupational safety and health topics, contact NIOSH

Telephone: 1-800-CDC-INFO (1-800-232-4636)

TTY: 1-888-232-6348

email: cdcinfo@cdc.gov

or visit the NIOSH website at http://www.cdc.gov/niosh

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