FactSheet

Mold Hazards during Disaster Cleanup

Flood and water damage inside buildings after disasters contribute to the growth of 

mold. Remediation of mold-contaminated building materials can be done safely.

What is Mold and Why is it Hazardous?

Mold is a type of fungi. Most molds reproduce 

by forming spores which are released into the air. 

When spores land on a suitable moist surface they 

begin to grow, can penetrate porous materials 

and release chemicals. Most molds are harmless 

but some can cause infections, allergy symptoms 

and produce toxins. Infections are rare in healthy 

individuals and the effect of toxins is still not well 

understood. Nevertheless, mold remediation is 

often necessary to return working spaces to a safe 

condition and make them suitable for occupancy. 

Mold Clean-up Plan

The most important requirement is to control 

the source of moisture. Next, survey the types of 

materials and the size of the area involved. This 

may become important in determining the strategy 

for remediation and worker protection. Materials 

that cannot be dried and fully cleaned are removed 

using methods that minimize occupant exposure 

to spores. Mold remediation often involves 

construction activities.

Note: Drying can involve the use of fans, blowers 

and/or dehumidifiers. However, the more humid 

the air, the less effective the blowers will be. 

Note: It is often more cost-effective to remove 

and replace the building materials than to dry and 

clean mold-contaminated materials. 

Types of Building Materials: Porous 

(water absorbing), Non-porous, or 

Semi-porous

Non-porous materials (e.g., metal, glass, hard 

plastics, etc.) can be dried out, fully cleaned and 

reused. Clean hard and non-porous materials 

using a detergent. Surfaces can be rinsed with a 

disinfectant made of 1⁄2 cup liquid household bleach 

mixed into one gallon of water (Caution: DO NOT 

mix bleach with cleaning products that contain 

ammonia). 

Semi-porous materials (e.g., wood and concrete) 

can be cleaned if they are structurally sound. 

Porous materials (e.g., drywall, carpets, insulation, 

ceiling tile, etc.) are different because mold 

penetrates into them making it very difficult to fully 

clean. As a general rule, if a porous material has 

been wet for over 48 hours it is best to remove and 

replace. 

How Big an Area is Involved in Mold 

Remediation?

Small Areas of Mold Remediation (i.e., < 30 ft.2) 

As a general rule, small areas of water damage 

require less control when remediating. 

• The work area should be unoccupied; removing

people from adjacent spaces is not necessary

but is recommended for infants, persons

recovering from surgery, immune suppressed

people, or people with asthma, hypersensitivity

pneumonitis and severe allergies.

• Containment of the work area is not necessary.

• Cover surfaces in the work area that could

become contaminated with secured plastic

sheets to contain dust and debris, and prevent

further contamination.

Large Areas of Mold Remediation (i.e., 30-100 ft.2)

• The work area and areas directly adjacent to it

should be unoccupied.

• Cover surfaces in the work area and adjacent

areas that could become contaminated with

secured plastic sheets to contain spores, dust and

debris to prevent further contamination.

• Seal ventilation ducts/grills in the work area and

areas directly adjacent with plastic sheeting.

• If remediation procedures are expected to

generate a lot of dust (e.g., abrasive cleaning of

contaminated surfaces, demolition of plaster

walls) or the visible concentration of mold is

heavy (i.e., blanket versus patchy coverage)

follow the extensive contamination procedures

below.

Extensive and Visible Mold Contamination

• Develop a suitable mold remediation plan. The

plan should address: work area isolation, the use

of exhaust fans with high-efficiency particulate

air (HEPA) filtration, and the design of airlocks/

decontamination room.
DTSEM FS-3713 09/2013

• Consult with industrial hygienists or other

environmental health and safety professionals

with experience performing mold remediation

before beginning this level of remediation.

How to Protect Workers during Mold 

Remediation

Worker protection uses engineering controls, work 

practices and personal protective equipment (PPE) 

during mold remediation. Inhalation is the route of 

exposure of most concern to cleanup workers.

Engineering Controls

• Re-wetting materials with a mist of water to

suppress spores, dust and debris.

• Wrap and seal the items that will be discarded

in plastic bags or sheets to reduce the spread of

spores.

• Provide natural or local exhaust ventilation during

all cleaning steps.

Work Practices 

• Do not eat, drink, or smoke in work areas.

• Avoid breathing dusts.

• After an area has been cleaned and is completely

dry, vacuum the area with a HEPA vacuum. HEPA

vacuums are also recommended for cleaning up

dust that may have settled on surfaces outside

the work area.

• The work area and areas used by remediation

workers for egress should be cleaned with a

damp cloth or mop and a detergent solution. Set

up a decontamination area.

• Leave the area clean, dry and free of visible

debris.

• After working, wash thoroughly, including hair,

scalp and nails.

Personal Protective Equipment (PPE)

• Respirators:

° For areas smaller than 100 ft.2

; use an approved

respirator, at a minimum, either a half-face or 

full-face N, R, or P-95 respirator.

° For areas greater than 100 ft.2

, areas where 

mold is heavy (blanket coverage rather than 

patchy), or areas where substantial dust is 

generated during cleaning or debris removal 

(e.g., abrasives are used to clean surfaces); use

an approved respirator, at a minimum, either a 

half-face or full-face N, R, or P-100 respirator.

° Charcoal-impregnated filters may be used for 

odors.

• Non-vented goggles.

• Long gloves made of material that will protect

workers from chemicals used for surface

cleaning.

• Protective clothing (e.g., disposable coveralls)

to prevent contamination and skin contact with

mold and chemicals. For areas greater than

100 ft.2, ensure that protective clothing covers

entire body including head and feet.

Additional Information

Visit OSHA’s Safety and Health Topics webpage on 

Mold at: www.osha.gov/SLTC/molds

This is one in a series of informational fact sheets highlighting OSHA programs, policies, or 

standards. It does not impose any new compliance requirements. For a comprehensive list of 

compliance requirements of OSHA standards or regulations, refer to Title 29 of the Code of Federal 

Regulations. This information will be made available to sensory-impaired individuals upon request. 

The voice phone is (202) 693-1999; teletypewriter (TTY) number: (877) 889-5627.