NIOSH Interim Recommendations for the Cleaning and Remediation of Flood-Contamin

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NIOSH Interim Recommendations for the Cleaning and

Remediation of Flood-Contaminated HVAC Systems:

A Guide for Building Owners and Managers

http://www.cdc.gov/niosh/topics/flood/pdfs/Cleaning-Flood-HVAC.pdf

Introduction

During flooding, systems for heating, ventilating, and air

conditioning (HVAC) can

become submerged in flood waters. As a result, these systems may

contain substantial

amounts of dirt and debris and may also become contaminated with

various types of

microorganisms such as bacteria and fungi. If the HVAC systems are

not cleaned and

disinfected properly, these microorganisms can be spread throughout

the entire

building. These microorganisms can cause building occupants to have

a variety of health

effects such as itchy eyes, runny nose, sneezing, and difficulty in

breathing. In addition,

the symptoms of people with allergies and asthma may get worse.

Exposures to

microorganisms have been documented to cause allergic respiratory

diseases in

agricultural, biotechnology, office, and home environments.1-8

Microorganisms may grow on all surfaces of HVAC system components

that were

submerged in flood waters. In addition, moisture can collect in HVAC

system

components that were not submerged (such as air supply ducts above

the water line)

and can promote the growth of microorganisms. Therefore, all

components of the HVAC

system that were contaminated with flood water or moisture should be

thoroughly

inspected, cleaned of dirt and debris, and disinfected by a

qualified professional. The

following recommendations will help ensure that HVAC systems

contaminated with

flood water are properly cleaned and remediated to provide healthy

indoor

environments. These interim recommendations are based on current

knowledge as of

September 21, 2005; the recommendations will be updated and revised

as appropriate,

as additional information becomes available.

Steps Before Cleaning and Remediation

! If the building is to remain partly occupied (for example, on

upper floors not

affected by flood waters), isolate the construction areas where HVAC

systems

will be cleaned and remediated by using temporary walls, plastic

sheeting, or

other vapor-retarding barriers. Maintain the construction areas

under negative

pressure (relative to adjacent non-construction areas) by using

blowers equipped

with HEPA filters (high-efficiency particulate air filters) to

exhaust the area.

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To ensure complete isolation from the construction areas, it may be

necessary to

pressurize the adjacent non-construction areas and temporarily

relocate the

outdoor-air intake for the HVAC system serving the occupied areas.

! Take precautions to protect the health of workers who are cleaning

and

remediating the HVAC system. Make sure that workers wear at least an

N-95

NIOSH-approved respirator to protect against airborne microorganisms.

Increased levels of respiratory protection (for example, powered,

air-purifying

respirators equipped with HEPA filters) may be appropriate depending

on the

level of visible contamination. In addition, when using chlorine

bleach or other

disinfectants in poorly ventilated environments, it may be necessary

to use

appropriate chemical cartridges in addition to the particulate

filters to protect

workers from breathing the chemical vapors. Employers must implement

a

complete respiratory protection program that meets the requirements

of the

OSHA respiratory protection standard (29 Code of Federal Regulations

1910.134).9 The minimum requirements for a respiratory protection

program

include a written standard operating procedure for the following:

selecting and

using respirators; the medical evaluation of workers to determine

whether they

are physically able to wear the respirator selected for use;

training and

instructions on respirator use; the cleaning, repair, and storage of

respirators; the

continued surveillance of work area conditions for worker exposure

and stress;

and a respirator fit-testing program. For tight-fitting respirators,

fit-testing is

necessary to help ensure that the respirator fits tightly, reducing

the potential for

leakage of outside air from around the edge of the mask. In

addition, employers

must provide workers with appropriate skin, eye, and hearing

protection for the

safe performance of their jobs.

! Determine whether any asbestos-containing materials are present by

having the

HVAC system inspected by a qualified professional. If asbestos is

determined to

be present, follow Federal, State, and local requirements for

removal and

disposal of the asbestos-containing materials before proceeding with

HVAC

system cleaning and remediation. Additional information about

protecting

workers from asbestos hazards during flood cleanup is available from

OSHA at

http://www.osha.gov/OshDoc/data_Hurricane_Facts/AsbestosHazards.pdf

HVAC Cleaning and Remediation

! Remove all flood-contaminated insulation surrounding and within

HVAC system

components. Discard these contaminated materials appropriately

following

applicable Federal, State, and local regulations.

! Remove contaminated HVAC filter media and discard appropriately

following

applicable Federal, State, and local regulations.

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! After removing any insulation and filters, clean all flood-

contaminated HVAC

system component surfaces with a HEPA-filtered vacuum cleaner to

remove dirt,

debris, and microorganisms. Pay special attention to filter racks,

drain pans,

bends and horizontal sections of air ducts where debris can collect.

! After removing any insulation or debris, disinfect all HVAC system

component

surfaces while the HVAC system is not operating. Use a solution of 1

cup of

household chlorine bleach in a gallon of water. Do not mix bleach

with other

cleaning products that contain ammonia.

! Follow the disinfection procedure with a clean water rinse.

Depending on the

amount of debris present, it may be necessary to mechanically clean

the HVAC

system component surfaces with a steam or a high-pressure washer

before

using the disinfectant.

Note: Remove and discard HVAC system components that are

contaminated with flood water and cannot be effectively cleaned and

disinfected. Replace them with new components.

! After cleaning and disinfecting or replacing the HVAC system

components,

replace the insulation – preferably with an external (i.e. not in

the air stream)

smooth-surfaced insulation to help prevent debris and microorganisms

from

collecting in the future.

! Make sure that the HVAC system fan has been removed and serviced

(cleaned,

disinfected, dried thoroughly, and tested) by a qualified

professional before it is

placed back into the air-handling unit.

! During the cleaning and remediation process, consider upgrading

the HVAC

system filtration to the highest efficiency filters practical given

the static pressure

constraints of the HVAC system fan. This step has been shown to be

one of the

most cost-effective ways to improve the long-term quality of the

indoor

environment, since it reduces the amount of airborne dusts and

microorganisms.

Resuming HVAC Operations

! After cleaning and disinfecting or replacing HVAC system, have a

qualified

professional thoroughly evaluate its performance and correct it as

necessary

before the building is occupied again. The HVAC system performance

should

conform to the recommendations contained in ASHRAE Standard 62-2004,

Ventilation for Acceptable Indoor Air Quality. 10

! Before the building is occupied again, operate the HVAC system

continuously in

a normal manner at a comfortable temperature for 48 to 72 hours.

During this

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period, it may be beneficial to open the HVAC outdoor air dampers to

the

maximum setting that still allows you to provide the desired indoor

air

temperatures. If objectionable flood-related odors persist after

this " flush out "

period, reassess by looking for flood-contaminated areas that were

not identified

earlier and continue the flush-out process until odors are no longer

apparent.

Replace the HVAC filters used during the flush-out prior to building

occupancy.

! After a building is occupied again, make frequent (for example,

weekly) checks of

the HVAC system to ensure that it is operating properly. During

these checks,

inspect the HVAC system filters and replace them when necessary.

Gradually

reduce the frequency of the HVAC system checks to monthly or

quarterly

inspections, depending on the routine operation and maintenance

specifications

for the HVAC system.

! If no routine operation and maintenance program is in place for

the HVAC

system, develop and institute such a program. At a minimum, include

the

following routine procedures: inspection and maintenance of HVAC

components,

calibration of HVAC system controls, and testing and balancing of

the HVAC

system.

! After the building is occupied again, maintain the interior

temperature and relative

humidity to conform with the ranges recommended in ASHRAE Standard

55-

2004, Thermal Environmental Conditions for Human Occupancy.11

Additional Resources

Additional information about the cleanup and restoration of water-

damaged and moldcontaminated

HVAC systems is available from the Institute of Inspection, Cleaning

and

Restoration Certification (IICRC) and the National Air Duct Cleaners

Association

(NADCA). Their pertinent documents (Standard and Reference Guide for

Professional

Mold Remediation [iICRC S520] and Assessment, Cleaning and

Restoration of HVAC

Systems [ACR 2005]) are available for purchase at www.iicrc.org/home

and

www.nadca.com/_secure/bookstore.asp, respectively. The University of

Minnesota also

has a document titled, " HVAC System Decontamination " available for

free off the

internet at www.dehs.umn.edu/iaq/hvacsys.html.

References

1. Vinken W, Roels P [1984]. Hypersensitivity pneumonitis to

Aspergillus fumigatus in

compost. Thorax 39:74-74.

2. Malmberg P, Rask-Andersen A, Palmgren U, Höglund S, Kolmodin-

Hedman B,

StDlenheim G [1985]. Exposure to microorganisms, febrile and

airwayPage

5 of 5

obstructive symptoms, immune status, and lung function of Swedish

farmers.

Scandinavian Journal of Work and Environmental Health 11:287-293.

3. Topping MD, Scarsbrick DA, Luczynska CM, e EC, Seaton A

[1985]. Clinical

and immunological reactions to Aspergillus niger among workers at a

biotechnology plant. British Journal of Industrial Medicine 42:312-

318.

4. JH [1980]. Microbial and immunological investigations and

remedial action

after an outbreak of humidifier fever. British Journal of Industrial

Medicine 37:55-

62.

5. Weiss NS, Soleymani Y [1971]. Hypersensitivity lung disease

caused by

contamination of an air-conditioning system. ls of Allergy

29:154-156.

6. Hodgson MJ, Morey PR, Attfield M, Sorenson W, Fink JN, WW,

Visvesvara

GS [1985]. Pulmonary disease associated with cafeteria flooding.

Archives of

Environmental Health 40(2):96-101.

7. Fink JN, Banaszak EF, Thiede WH, Barboriak JJ [1971].

Interstitial pneumonitis due

to hypersensitivity to an organism contaminating a heating system.

ls of

Internal Medicine 74:80-83.

8. Banazak EF, Barboriak J, Fink J, Scanlon G, Schlueter EP, Sosman

A, Thiede W,

Unger G [1974]. Epidemiologic studies relating thermophilic fungi and

hypersensitivity lung syndrome. American Review of Respiratory

Disease

110:585-591.

9. OSHA [1998]. Occupational Safety and Health Standards (29 CFR

1910.134).

Occupational Safety and Health Administration, Washington, D.C.

10. ASHRAE [2004]. ASHRAE Standard 62-2004: Ventilation for

Acceptable Indoor Air

Quality. American Society of Heating, Refrigerating, and Air-

conditioning

Engineers, Atlanta, GA.

11. ASHRAE [2004]. ANSI/ASHRAE Standard 55-2004: Thermal

Environmental

Conditions for Human Occupancy. American Society for Heating,

Refrigerating,

and Air-conditioning Engineers, Atlanta, GA.