U.S. Environmental Protection Agency (EPA)

Mold Web Course

PDF Version

www.epa.gov/mold/moldcourse
2 

Introduction to Mold and Mold Remediation for 

Environmental and Public Health Professionals 

This web course contains information on mold prevention and 

remediation. It is designed primarily for environmental and 

public health professionals. 

If you would like to take a short quiz on your current mold 

knowledge, begin with the Pre-Test. 

The Mold Course has nine chapters; these chapters are 

further divided into smaller lessons. At the end of each 

chapter is a voluntary quiz to test your understanding of the 

material covered. Each chapter may be accessed at any point 

in the course using the menu on the left side of the page. 

For general information on mold, flooding, EPA mold 

brochures, and other mold and moisture control related 

resources, please visit the EPA mold Web site 

www.epa.gov/mold. 
3 

MOLD REMEDIATION PRE-TEST

QUESTION 1 

The most important factor influencing mold growth is: 

• A. Temperature 

• B. Light 

• C. Moisture or water 

• D. Organic matter 
4 

MOLD REMEDIATION PRE-TEST

QUESTION 1 

The most important factor influencing mold growth is: 

• A. Temperature 

• B. Light 

• C. Moisture or water 

• D. Organic matter 

The correct answer is C.
5 

MOLD REMEDIATION PRE-TEST

QUESTION 2 

Molds have the potential to cause health effects such as allergic reactions. 

• True 

• False 
6 

MOLD REMEDIATION PRE-TEST

QUESTION 2 

Molds have the potential to cause health effects such as allergic reactions. 

• True 

• False 

The correct answer is "True."
7 

MOLD REMEDIATION PRE-TEST

QUESTION 3 

Personal Protective Equipment (PPE) is worn in order to limit mold exposure. Minimum PPE for mold 

remediation includes: 

• A. A helmet and gloves 

• B. Safety glasses and protective shoes 

• C. An N-95 respitator, gloves, and goggles 
8 

MOLD REMEDIATION PRE-TEST

QUESTION 3 

Personal Protective Equipment (PPE) is worn in order to limit mold exposure. Minimum PPE for mold 

remediation includes: 

• A. A helmet and gloves 

• B. Safety glasses and protective shoes 

• C. An N-95 respitator, gloves, and goggles 

The correct answer is C. 
9 

MOLD REMEDIATION PRE-TEST

QUESTION 4 

Water-damaged furnishings and building components should be dried within 24-48 hours to prevent mold 

growth. 

• True 

• False 
10 

MOLD REMEDIATION PRE-TEST

QUESTION 4 

Water-damaged furnishings and building components should be dried within 24-48 hours to prevent mold 

growth. 

• True 

• False 

The correct answer is "True."
11 

MOLD REMEDIATION PRE-TEST

QUESTION 5 

Mold cannot be eliminated from indoor environments. Some mold spores will be found floating through the 

air and in dust; however, they will not grow if moisture is not present. 

• True 

• False 
12 

MOLD REMEDIATION PRE-TEST

QUESTION 5 

Mold cannot be eliminated from indoor environments. Some mold spores will be found floating through the 

air and in dust; however, they will not grow if moisture is not present. 

• True 

• False 

The correct answer is "True."
How to Use this Course 

Overview 

This course provides an overview of mold prevention and mold remediation. It is based on EPA's voluntary 

guidance document Mold Remediation in Schools and Commercial Buildings. Public health and environmental 

health professionals who are involved with mold issues may be interested in this course. Building managers, 

custodians, remediators, contractors, and other professionals who respond to mold problems may also want to 

refer to this course. 

Please note that the course and the document on which it is based provide guidelines; other cleaning and 

remediation methods may be preferred by some professionals. This course does not cover all situations and all 

potentially useful methods or techniques. The absence of a method or technique from this course does not 

indicate or imply that it is not effective. Please consult the Resource List for additional information. A printable 

PDF Version (PDF, 202 pp, 5.5MB) of the course, an Image Library and Glossary of Terms are also available. 

These guidelines are for damage caused by clean water (not flood water); see the EPA Fact Sheet: Flood 

Cleanup - Avoiding Indoor Air Quality Problems for flood information. 

Research on mold and on its health effects continues. This course does not describe all of the potential health 

effects related to mold exposure; it provides only an overview. For more detailed information, consult a health 

professional or your state or local health department. 

EPA does not regulate mold or mold spores in the air. 

Disclaimer: This course provides information on mold prevention and remediation. This course is based on 

the U.S. Environmental Protection Agency (EPA) voluntary guidance document Mold Remediation in Schools 

and Commercial Buildings. Please note: This course is free and available to all. EPA will not provide a 

certificate, certification, or any other credential for viewing the course — it is for informational purposes only. 

Some organizations may choose to offer continuing education credits (CEUs) for completion of the course. The 

knowledge tests are for the information of the person taking the course only. EPA does not track test results or 

provide the information to any other party. All participation in the course is completely anonymous. 

Best Settings to View this Training 

This site works best if you use a recent-version browser such as Microsoft Internet Explorer ver. 5.5 or higher, 

have a screen resolution of 1024x768 or higher, and have JavaScript enabled on your browser. If you don't 

know how to check this, please look at the Help feature of your browser or ask your local computer help 

person. This site uses occasional pop-up windows to provide in-depth information and high-resolution images. 

Disable your pop-up blocker if you use one. Please contact us if you have problems with accessibility on these 

pages. 

To download the browser, see www.microsoft.com/windows/ie/default.mspx 

Navigation 

You can navigate among the main elements of this training course using the vertical menu bar on the left. Click 

on an entry to move between chapters or to the access the image library (on the home page), knowledge tests, 

resource list, or glossary. 

13
Within the chapters, you can move from lesson to lesson or to the chapter knowledge test using the menu on 

the right. Links on either side of the bottom of each lesson will also move you to the next lesson. 

Pre-Test and Knowledge Tests 

Take the pre-test (accessed from the home page) prior to taking the course to see if you know five basic facts 

about mold. 

At the end of each chapter, a knowledge test reviews important information from each of its lessons. Select an 

answer and the screen will tell you whether your answer is correct; it will also direct you back to the lesson 

where you can review the information. If you are unsure of an answer, click “Reveal Answer.” A counter keeps 

track of the number of questions you have answered and your score. The scores are for your information only. 

EPA does not track your test results or provide the information to any other party. 

Image Library 

The image library, accessed on the home page, contains mold-related images in seven categories: mold in the 

environment; magnified mold; moisture and moisture damage; prevention; mold in buildings; finding mold and 

moisture; and cleaning and remediation. Each photo has an identifying caption and a high-resolution version. 

To download a photo, open and right click on the high-resolution photo. Choose whether you want to copy or 

save the photo. If saving, a dialogue box will appear so you can specify where to save the photo. These photos 

may be used for presentations and educational purposes without contacting EPA — please see the EPA 

Privacy and Security Notice for more information. 

Resource List 

The Resource List provides links to documents and Web sites that provide additional information on mold, 

mold prevention, and mold remediation. The list includes EPA documents and Web sites, as well as 

information created and maintained by other public and private organizations. EPA does not control or 

guarantee the accuracy, relevance, timeliness, or completeness of this outside information. Further, inclusion 

of such resources is not intended to endorse any views expressed or products or services offered by the 

author of the reference or the organization operating the service on which the reference is maintained. 

14
15 

Course Chapters 

Chapter 1- Introduction to Mold 

• Lesson 1 - What Molds Are 

• Lesson 2 - What Mold Needs to Grow 

• Lesson 3 - Health Effects That May Be Caused by Inhaling Mold or Mold Spores 

• Lesson 4 - Mycotoxins and Health Effects 

• Lesson 5 - The Color of Mold 

• Lesson 6 - Moldy Smell 

• Knowledge Test 

Chapter 2- Where and Why Mold Grows 

• Lesson 1 - Introduction to Mold Growth 

• Lesson 2 - Moisture Problems 

• Lesson 3 - Humidity 

• Lesson 4 - Ventilation Humidity Problems 

• Lesson 5 - Structural Integrity and Mold Growth 

• Lesson 6 - Crawl Spaces 

• Lesson 7 - Floods 

• Knowledge Test 

Chapter 3- Finding Mold and Moisture 

• Lesson 1 - Where to Look for Mold Contamination - Building Investigation 

• Lesson 2 - Equipment for Identifying Mold 

• Lesson 3 - Mold Sampling Considered 

• Knowledge Test 

Chapter 4- General Remediation Issues 

• Lesson 1 - Dry Quickly 

• Lesson 2 - Assess Mold Problem 

• Lesson 3 - Remediation Plan 

• Lesson 4 - Mold Remediation Procedures 

• Table 1 

• Table 2 

• Knowledge Test 

Chapter 5- Large Areas and Other Special Concerns 

• Lesson 1 - Remediating Large Areas of Mold Contamination 

• Lesson 2 - Mold Remediation in Heating, Ventilation, and Air Conditioning (HVAC) Systems 

• Lesson 3 - Confined Spaces 

• Knowledge Test 

Chapter 6- Containment and Personal Protective Equipment (PPE) 

• Lesson 1 - Overview of Containment 
16 

• Lesson 2 - Limited Containment 

• Lesson 3 - Full Containment 

• Lesson 4 - Personal Protective Equipment (PPE) 

• Knowledge Test 

Chapter 7- Evaluating the Remediation 

• Lesson 1 - Completing Mold Remediation - Fix the water problem and clean up the mold 

• Lesson 2 - Considering Bioaerosol Sampling 

• Knowledge Test 

Chapter 8- Communicating with the Building Occupants 

• Lesson 1 - Communicate When You Remediate 

• Knowledge Test 

Chapter 9- Prevention 

• Lesson 1 - Mold Prevention 

• Knowledge Test 
17 

CHAPTER 1

INTRODUCTION TO MOLD 

Lesson 1 What Molds Are

Molds are organisms that may be found indoors and outdoors. They are part of the 

natural environment and play an important role in the environment by breaking down and 

digesting organic material, such as dead leaves. Also called fungi or mildew, molds are 

neither plants nor animals; they are part of the kingdom Fungi. 

Molds can multiply by producing microscopic spores (2 - 100 microns 

[μm] in diameter), similar to the seeds produced by plants. Many 

spores are so small they easily float through the air and can be 

carried for great distances by even the gentlest breezes. The number of mold spores 

suspended in indoor and outdoor air fluctuates from season to season, day to day, and 

even hour to hour. 

Mold spores are ubiquitous; they are found both indoors and outdoors. Mold spores 

cannot be eliminated from indoor environments. Some mold spores will be found floating 

through the air and in settled dust; however, they will not grow if moisture is not present. 

Mold is not usually a problem indoors—unless mold spores land on a wet or damp spot and begin growing. 

As molds grow they digest whatever they are growing on. Unchecked mold growth can damage buildings 

and furnishings; molds can rot wood, damage drywall, and eventually cause structural damage to buildings. 

Mold can cause cosmetic damage, such as stains, to furnishings. The potential human health effects of mold 

are also a concern. It is important, therefore, to prevent mold from growing indoors. 
18 

CHAPTER 1

INTRODUCTION TO MOLD 

Lesson 2 What Mold Needs to Grow

To grow indoors, mold needs moisture and food. Moisture is the most important factor influencing mold 

growth indoors. Controlling indoor moisture helps limit mold growth. 

Moisture control is the key to mold control. 

Mold does not need a lot of water to grow. A little condensation, in a bathroom or 

around a window sill, for example, can be enough. Common sites for indoor mold 

growth include bathroom tile and grout, basement walls, and areas around windows, 

near leaky water fountains, and around sinks. Common sources of water or moisture 

include roof leaks, condensation due to high humidity or cold spots in a building, slow 

leaks in plumbing fixtures, humidification systems, sprinkler systems, and floods.* 

Besides moisture, mold needs nutrients, or food, to grow. Mold can grow on virtually 

any organic substance. Most buildings are full of organic materials that mold can use as food, including 

paper, cloth, wood, plant material, and even soil. In most cases, temperature is not an issue; some molds 

grow in warm areas, while others prefer cool locations such as bread stored in a refrigerator. Often, more 

than one type of mold can be found growing in the same area, although conditions such as moisture, light, 

and temperature may favor one species of mold over another. 

*Floods

Buildings that have been heavily damaged by flood waters should be 

assessed for structural integrity and remediated by experienced 

professionals. Please note that the guidelines covered in this course were 

developed for damage caused by clean water (not flood water, sewage, or 

other contaminated water). See the EPA Resource List, which includes the 

EPA Fact Sheet: Flood Cleanup - Avoiding Indoor Air Quality Problems, 

for more information. 
19 

CHAPTER 1

INTRODUCTION TO MOLD 

Lesson 3 Health Effects That May Be Caused by Inhaling Mold or Mold 

Spores

Inhalation exposure to mold indoors can cause health effects in some people. Molds produce allergens 

(substances that can cause allergic reactions), irritants, and, in some cases, potentially toxic substances or 

chemicals (mycotoxins). Inhaling or touching mold or mold spores may cause allergic reactions in sensitive 

individuals. Mold does not have to be alive to cause an allergic reaction. Dead or alive, mold can cause 

allergic reactions in some people. 

Allergic Reactions, Asthma Attacks, Irritant Effects

Allergic reactions to mold are common and can be immediate or delayed. Repeated or single exposure to 

mold, mold spores, or mold fragments may cause non-sensitive individuals to become sensitive to mold, and 

repeated exposure has the potential to increase sensitivity. Allergic responses include hay fever-like 

symptoms such as headache, sneezing, runny nose, red eyes, and skin rash (dermatitis). Molds can cause 

asthma attacks in people with asthma who are allergic to mold. In addition, molds can irritate the eyes, skin, 

nose, throat, and lungs of individuals whether or not they are allergic to mold. 

Other Health Effects

Breathing in mold may also cause hypersensitivity pneumonitis, an uncommon disease that resembles 

bacterial pneumonia. In addition, mold exposure may result in opportunistic infections in persons whose 

immune systems are weakened or suppressed. 

When mold grows indoors, the occupants of a building may begin to report odors and a variety of symptoms 

including headaches, difficulty breathing, skin irritation, allergic reactions, and aggravated asthma symptoms. 

These and other symptoms may be associated with exposure to mold. But all of these symptoms may be 

caused by other exposures or conditions unrelated to mold growth. Therefore, it is important not to assume 

that, whenever any of these symptoms occurs, mold is the cause. 

For more detailed information on mold and its health effects, consult a health professional. You may also 

wish to consult your state or local health department. ( Also see the Resource List for additional information.) 

Damp Buildings

Although mold is frequently found in damp buildings, it is not the only potential contaminant —

biological contaminants other than mold, and nonbiological contaminants are often present and 

may also cause health effects. Damp buildings may attract rodents and other pests. Damp or 

wet building components and furnishings may release chemicals indoors. 

Potential contaminants in damp or wet buildings include bacteria, dust mites, cockroaches and 

other pests, as well as chemicals emitted by damp building materials and furnishings. For more 

information on damp buildings and health effects, see the 2004 Institute of Medicine Report, 

Damp Indoor Spaces and Health, published by The National Academies Press in Washington, 

DC, and available on the Web. See Resource List for Web link. 
20 

CHAPTER 1

INTRODUCTION TO MOLD 

Lesson 4 Mycotoxins and Health Effects

As molds grow, some (but not all) of them may produce potentially toxic byproducts called mycotoxins under 

some conditions. Some of these molds are commonly found in moisture-damaged buildings. More than 200 

mycotoxins from common molds have been identified, and many more remain to be identified. The amount 

and types of mycotoxins produced by a particular mold depends on many environmental and genetic factors. 

No one can tell whether a mold is producing mycotoxins just by looking at it. Some mycotoxins are known to 

affect people, but for many mycotoxins little health information is available. Research on mycotoxins is 

ongoing. Exposure to mycotoxins can occur from inhalation, ingestion, and skin contact. It is prudent to avoid 

unnecessary inhalation exposure to mold. 

For more information on mycotoxins, see the 2004 Institute of Medicine Report, Damp Indoor 

Spaces and Health, published by The National Academies Press in Washington, DC, and 

available on the Web. See Resource List for Web link. 
21 

CHAPTER 1

INTRODUCTION TO MOLD 

Lesson 5 The Color of Mold

Molds come in many colors including white. "Black mold" is not a species or specific kind 

of mold, and neither is "toxic mold." Sometimes the news media use the terms "toxic 

mold" and "black mold" to refer to molds that may produce mycotoxins or for a specific 

mold, Stachybotrys chartarum . Molds that produce mycotoxins are often referred to as 

toxigenic fungi. 
22 

CHAPTER 1

INTRODUCTION TO MOLD 

Lesson 6 Moldy Smell 

Some compounds produced by molds have strong smells and are volatile and quickly released into the air. 

These compounds are known as microbial volatile organic compounds (mVOCs). Because mVOCs often 

have strong or unpleasant odors, they can be the source of the "moldy odor" or musty smell frequently 

associated with mold growth. A moldy odor suggests that mold is growing in the building and should 

be investigated. 

The health effects of inhaling mVOCs are largely unknown, although exposure to mVOCs has been linked to 

symptoms such as headaches, nasal irritation, dizziness, fatigue, and nausea. More research is needed to 

determine whether there are any human health effects from nonoccupational indoor exposures to mVOCs. 
23 

CHAPTER 1

INTRODUCTION TO MOLD 

Lesson 7 Biocides 

Biocides are substances that can destroy living organisms. The use of a biocide or a chemical that kills 

organisms such as mold (chlorine bleach, for example) is not recommended as a routine practice during 

mold cleanup. There may be instances, however, when professional judgment indicates their use (for 

example, when immune-compromised individuals are present). 

In most cases, it is not possible or desirable to sterilize an area; a background level of mold spores will 

remain, but these spores will not grow if the moisture problem has been resolved. If disinfectants or biocides 

are used, always ventilate the area and exhaust the air to the outdoors. Never mix chlorine bleach with other 

cleaning solutions or with detergents that contain ammonia because toxic fumes could be produced. 

Please note: Dead mold is allergenic and may cause allergic reactions and other health effects in some 

individuals, so it is not enough to simply kill the mold. It must also be removed. 
24 

MOLD REMEDIATION KNOWLEDGE TEST

Chapter 1 Introduction to Mold 

Lesson 1 What Molds Are 

QUESTION 1 

Mold spores are usually found in indoor air. 

Please click on your answer. 

• True 

• False 
25 

MOLD REMEDIATION KNOWLEDGE TEST

Chapter 1 Introduction to Mold 

Lesson 1 What Molds Are 

QUESTION 1 

Mold spores are usually found in indoor air. 

Please click on your answer. 

• True 

• False 

 

The correct answer is "True." 

This topic was covered in Chapter 1, Lesson 1. 
26 

MOLD REMEDIATION KNOWLEDGE TEST

Chapter 1 Introduction to Mold 

Lesson 2 What Mold Needs to Grow 

QUESTION 2 

The most important factor influencing mold growth indoors is: 

Please click on your answer. 

• A. Temperature 

• B. Light 

• C. Moisture or water 

• D. Organic matter 
27 

MOLD REMEDIATION KNOWLEDGE TEST

Chapter 1 Introduction to Mold 

Lesson 2 What Mold Needs to Grow 

QUESTION 2 

The most important factor influencing mold growth indoors is: 

Please click on your answer. 

• A. Temperature 

• B. Light 

• C. Moisture or water 

• D. Organic matter 

 

The correct answer is C. 

This topic was covered in Chapter 1, Lesson 2. 
28 

MOLD REMEDIATION KNOWLEDGE TEST

Chapter 1 Introduction to Mold 

Lesson 2 What Mold Needs to Grow 

QUESTION 3 

Molds can grow in cold places. 

Please click on your answer. 

• True 

• False 
29 

MOLD REMEDIATION KNOWLEDGE TEST

Chapter 1 Introduction to Mold 

Lesson 2 What Mold Needs to Grow 

QUESTION 3 

Molds can grow in cold places. 

Please click on your answer. 

• True 

• False 

 

The correct answer is "True." 

This topic was covered in Chapter 1, Lesson 2. 
30 

MOLD REMEDIATION KNOWLEDGE TEST

Chapter 1 Introduction to Mold 

Lesson 3 Health Effects That May Be Caused by Inhaling Mold or Mold Spores 

QUESTION 4 

Dead mold is allergenic. 

Please click on your answer. 

• True 

• False 
31 

MOLD REMEDIATION KNOWLEDGE TEST

Chapter 1 Introduction to Mold 

Lesson 3 Health Effects That May Be Caused by Inhaling Mold or Mold Spores 

QUESTION 4 

Dead mold is allergenic. 

Please click on your answer. 

• True 

• False 

The correct answer is "True." 

This topic was covered in Chapter 1, Lesson 3. 
32 

MOLD REMEDIATION KNOWLEDGE TEST

Chapter 1 Introduction to Mold 

Lesson 4 Mycotoxins and Health Effects 

QUESTION 5 

All molds produce mycotoxins. 

Please click on your answer. 

• True 

• False 
33 

MOLD REMEDIATION KNOWLEDGE TEST

Chapter 1 Introduction to Mold 

Lesson 4 Mycotoxins and Health Effects 

QUESTION 5 

All molds produce mycotoxins. 

Please click on your answer. 

• True 

• False 

The correct answer is "False." 

This topic was covered in Chapter 1, Lesson 4. 
34 

MOLD REMEDIATION KNOWLEDGE TEST

Chapter 1 Introduction to Mold 

Lesson 5 The Color of Mold 

QUESTION 6 

All mold is black. 

Please click on your answer. 

• False 

• True 
35 

MOLD REMEDIATION KNOWLEDGE TEST

Chapter 1 Introduction to Mold 

Lesson 5 The Color of Mold 

QUESTION 6 

All mold is black. 

Please click on your answer. 

• False 

• True 

 

The correct answer is "False." 

This topic was covered in Chapter 1, Lesson 5. 
36 

MOLD REMEDIATION KNOWLEDGE TEST

Chapter 1 Introduction to Mold 

Lesson 6 Moldy Smell 

QUESTION 7 

A moldy odor in a building suggests that mold is growing in the building whether or not you see mold. 

Please click on your answer. 

• True 

• False 
37 

MOLD REMEDIATION KNOWLEDGE TEST

Chapter 1 Introduction to Mold 

Lesson 6 Moldy Smell 

QUESTION 7 

A moldy odor in a building suggests that mold is growing in the building whether or not you see mold. 

Please click on your answer. 

• True 

• False 

The correct answer is "True." 

This topic was covered in Chapter 1, Lesson 6. 
38 

MOLD REMEDIATION KNOWLEDGE TEST

Chapter 1 Introduction to Mold 

Lesson 7 Biocides 

QUESTION 8 

Routine use of biocides (such as chlorine bleach) in mold cleanup is NOT recommended. 

Please click on your answer. 

• True 

• False 
39 

MOLD REMEDIATION KNOWLEDGE TEST

Chapter 1 Introduction to Mold 

Lesson 7 Biocides 

QUESTION 8 

Routine use of biocides (such as chlorine bleach) in mold cleanup is NOT recommended. 

Please click on your answer. 

• True 

• False 

The correct answer is "True." 

This topic was covered in Chapter 1, Lesson 7. 
40 

CHAPTER 2

WHERE AND WHY MOLD GROWS 

Lesson 1 Introduction to Mold Growth

Mold can grow on virtually any organic material as long as moisture and oxygen are 

present. There are molds that grow on wood, paper, carpet, food, and insulation. 

Because mold eats or digests what it is growing on, it can damage a building and its 

furnishings. If left unchecked, mold eventually can cause structural damage to building 

materials. 

Molds gradually destroy the things they grow on. You can prevent damage to 

buildings and building contents, save money, and avoid potential health 

problems by controlling moisture and eliminating mold growth. 

Eliminating all mold and mold spores indoors is virtually impossible, but controlling indoor moisture will 

control the growth of indoor mold. 
41 

CHAPTER 2

WHERE AND WHY MOLD GROWS 

Lesson 2 Moisture Problems

Moisture problems can have many causes. Some moisture problems have been linked to 

changes in building construction practices since the 1970s. These practices led to 

buildings that are tightly sealed but, in some cases, lack adequate ventilation. Without 

adequate ventilation, moisture may build up indoors and mold may grow. 

A building must be properly designed for climate, site location, and use, and its design 

must be accurately followed during construction or the building may have moisturecontrol problems. For more information on building construction for moisture control, see 

the Resource List. 

Delayed or insufficient maintenance can lead to moisture problems in buildings. Undiscovered or ignored 

moisture problems can create an environment in which mold can grow. Moisture problems in temporary 

structures, such as portable classrooms, are also frequently associated with mold problems. 

Common moisture problems include: 

Leaking roofs. 

Leaking or condensing water pipes, especially pipes inside wall cavities or pipe chases. 

Leaking fire-protection sprinkler systems. 

Landscaping, gutters, and down spouts that direct water into or under a building. 

High humidity (> 60% relative humidity). 

Unvented combustion appliances such as clothes dryers vented into a garage. (Clothes dryers and other 

combustion appliances should be vented to the outside.) 

Some moisture problems are not easy to see. For example, the inside of walls where pipes and wires are run 

(pipe chases and utility tunnels) are common sites of mold growth. Mold is frequently found on walls in cold 

corners behind furniture where condensation forms. Other possible locations of hidden moisture, resulting in 

hidden mold growth are: 

Poorly draining condensate drain pains inside air handling units. 

Porous thermal or acoustic liners inside duct work. 

Roof materials above ceiling tiles. 

The back side of drywall (also known as gypsum board, wallboard, or SHEETROCK®), paneling, and 

wallpaper. 

The underside of carpets and pads. 

You may suspect mold, even if you can't see it, if a building smells moldy. You may also suspect hidden 

mold if you know there has been a water problem in the building and its occupants are reporting health 

problems. 

Building Design and Vapor Barriers

Many buildings incorporate vapor barriers in the design of their walls and floors. Vapor barriers 

must be located and installed properly or the building may have moisture problems. A vapor 

barrier is a layer of material that slows or prevents the absorption or release of moisture from or 

into a wall or floor. Vapor barriers can prevent damp or wet building materials from drying 

quickly enough to prevent mold growth. For more information on building design see the 

Resource List. 
42 

CHAPTER 2

WHERE AND WHY MOLD GROWS 

Lesson 3 Humidity

Sometimes, humidity or dampness (water vapor) in the air can supply enough moisture 

for mold growth. Indoor relative humidity (RH) should be kept below 60 percent — ideally 

between 30 percent and 50 percent, if possible. Low humidity may also discourage pests 

(such as cockroaches) and dust mites. 

Humidity levels can rise in a building as a result of the use of humidifiers, steam 

radiators, moisture-generating appliances such as dryers, and combustion appliances 

such as stoves. Cooking and showering also can add to indoor humidity. 

HVAC System

One function of the building heating, ventilation, and air conditioning (HVAC) system is to remove moisture 

from the air before the air is distributed throughout the building. If the HVAC system is turned off during or 

shortly after major cleaning efforts that involve a lot of water, such as mopping and carpet shampooing or 

cleaning, the humidity may rise greatly, and moisture or mold problems may develop. 

Condensation 

Condensation can be a sign of high humidity. When warm, humid air contacts a cold 

surface, condensation may form. (To see this, remove a cold bottle of water from a 

refrigerator and take it outside on a hot day. Typically, condensation will form on the 

outside of the bottle.) Humidity can be measured with a humidity gauge or meter; models 

that can monitor both temperature and humidity are generally available for less than $50 

at hardware stores or on the Internet. 
43 

CHAPTER 2

WHERE AND WHY MOLD GROWS 

Lesson 4 Ventilation Humidity Problems - Heating, Ventilation, and Air 

Conditioning (HVAC) System

Mold growing near the intake to an HVAC system indicates potential ventilation humidity problems. An HVAC 

system that is part of an identified moisture problem may also be a site of mold growth. Experience and 

professional judgment should be used when working with the HVAC system; consult a professional if 

needed. 

The HVAC system has the potential to spread mold throughout a building. Known or suspected mold growth 

in HVAC ducts or other system components should be investigated and resolved promptly. If substantial 

amounts of mold can be seen growing on the inside of hard surface ducts (e.g., ducts made of sheet metal), 

consider cleaning the ducts. Consult the EPA guide Should You Have the Air Ducts in Your Home Cleaned?

(see the Resource List). Although this publication focuses on ducts in homes, the information it contains is 

applicable to other building types. 

If the HVAC system has insulation on the inside of the air ducts, and the insulation gets wet or moldy, it 

should be removed and replaced because the material cannot be cleaned effectively. Please note that 

there are no antimicrobial products or biocides approved by EPA for use on lined ductwork. Consult 

the EPA Web site on antimicrobial pesticides for more information (see the Resource List). 

Controlling moisture is the most effective way of keeping mold from growing in air ducts. Steps to control 

moisture in ductwork include: 

Promptly and properly repairing any leaks or water damage. 

Removing standing water under the cooling coils of air handlers by making sure the drain pans slope 

toward the drain and the drain is flowing freely. 

Making sure ducts are properly sealed and insulated in all non-air-conditioned spaces so moisture due to 

condensation does not enter the system and the system works as intended. To prevent condensation, the 

heating and cooling system must be properly insulated. 

Operating and maintaining any in-duct humidification equipment strictly according to the manufacturer's 

recommendations. 

Making sure that carpets, drapes, furniture, and other furnishings are dried promptly after they have been 

cleaned. 
44 

CHAPTER 2

WHERE AND WHY MOLD GROWS 

Lesson 5 Structural Integrity and Mold Growth

Molds gradually destroy whatever they grow on, so preventing mold growth also prevents damage to building 

materials and furnishings. 

If a mold and moisture problem goes unaddressed long enough, structural damage is likely to result. For 

example, if a roof is allowed to leak long enough, molds can weaken floors and walls by feeding on the wet 

wood. 

When mold is suspected of causing damage to the structural integrity of a building, a structural engineer or 

other professional with relevant expertise should be consulted. 
45 

CHAPTER 2

WHERE AND WHY MOLD GROWS 

Lesson 6 Crawl Spaces

Crawl spaces where relative humidity (RH) is high are common sites of hidden mold 

growth, particularly if the crawl space has a bare earth floor. The soil will wick moisture, 

through capillary action, from moist to dry areas. The relative warmth of the crawl space 

will dry the soil by evaporation, adding this moisture to the air in the crawl space where it 

can cause mold to grow. Also, in areas where the water table is high and weather 

conditions are suitable, ground water may enter a crawl space. 

The moisture that accumulates in a crawl space may also enter another part of the 

building and contribute to mold growth there. Moisture can pass from a crawl space into a building through 

cracks in walls, floors, and ceilings. 

Crawl spaces should be designed specifically to avoid moisture problems. For information on constructing 

crawl spaces and other building features, see the Resource List. 

Drying Buildings, Building Materials, and Furnishings

Buildings and building furnishings will often get wet. They must be dried or "allowed to 

dry" quickly (within 24-48 hours) in order to avoid mold growth. In general, increasing air 

circulation and temperature will increase the speed of drying. 

Commercial firms that do mold remediation work or work on water- and fire-damaged 

buildings often use large fans, dehumidifiers, and other equipment to dry wet buildings 

and items quickly before mold has a chance to grow. This action can save money in the 

long run, because if the building or furnishings are dried completely and quickly, mold 

will not grow, and a mold remediation will not be needed. 
46 

CHAPTER 2

WHERE AND WHY MOLD GROWS 

Lesson 7 Floods

During a flood cleanup, the indoor air quality in your home or office may appear to be the least of your 

problems. However, failure to remove contaminated materials and to reduce moisture and humidity can 

present serious long-term health risks. Standing water and wet materials are a breeding ground for 

microorganisms, such as viruses, bacteria, and mold. They can cause disease, trigger allergic reactions, and 

continue to damage materials long after the flood. 

Buildings that have been heavily damaged by flood waters should be assessed for structural integrity and 

remediated by experienced professionals. 

Please note that the guidelines covered in this course were developed for damage caused by clean water 

(not flood water, sewage, or other contaminated water). See the Resource List, which includes the EPA 

Fact Sheet: Flood Cleanup - Avoiding Indoor Air Quality Problems, for more information. 
47 

MOLD REMEDIATION KNOWLEDGE TEST

Chapter 2 WHERE AND WHY MOLD GROWS 

Lesson 1 Introduction to Mold Growth 

QUESTION 1 

The way to control mold growth is to control moisture. 

Please click on your answer. 

• True 

• False 
48 

MOLD REMEDIATION KNOWLEDGE TEST

Chapter 2 WHERE AND WHY MOLD GROWS 

Lesson 1 Introduction to Mold Growth 

QUESTION 1 

The way to control mold growth is to control moisture. 

Please click on your answer. 

• True 

• False 

The correct answer is "True." 

This topic was covered in Chapter 2, Lesson 1. 
49 

MOLD REMEDIATION KNOWLEDGE TEST

Chapter 2 WHERE AND WHY MOLD GROWS 

Lesson 2 Moisture Problems 

 QUESTION 2 

Inadequate building ventilation can lead to mold growth. 

Please click on your answer. 

• True 

• False 
50 

MOLD REMEDIATION KNOWLEDGE TEST

Chapter 2 WHERE AND WHY MOLD GROWS 

Lesson 2 Moisture Problems 

QUESTION 2 

Inadequate building ventilation can lead to mold growth. 

Please click on your answer. 

• True 

• False 

The correct answer is "True." 

This topic was covered in Chapter 2, Lesson 2. 
51 

MOLD REMEDIATION KNOWLEDGE TEST

Chapter 2 WHERE AND WHY MOLD GROWS 

Lesson 3 Humidity 

QUESTION 3 

Using a stove can increase the humidity in a room. 

Please click on your answer. 

• True 

• False 
52 

MOLD REMEDIATION KNOWLEDGE TEST

Chapter 2 WHERE AND WHY MOLD GROWS 

Lesson 3 Humidity 

QUESTION 3 

Using a stove can increase the humidity in a room. 

Please click on your answer. 

• True 

• False 

The correct answer is "True." 

This topic was covered in Chapter 2, Lesson 3. 
53 

MOLD REMEDIATION KNOWLEDGE TEST

Chapter 2 WHERE AND WHY MOLD GROWS 

Lesson 3 Humidity 

QUESTION 4 

Condensation can be a sign of high humidity. 

Please click on your answer. 

• True 

• False 
54 

MOLD REMEDIATION KNOWLEDGE TEST

Chapter 2 WHERE AND WHY MOLD GROWS 

Lesson 3 Humidity 

QUESTION 4 

Condensation can be a sign of high humidity. 

Please click on your answer. 

• True 

• False 

The correct answer is "True." 

This topic was covered in Chapter 2, Lesson 3. 
55 

MOLD REMEDIATION KNOWLEDGE TEST

Chapter 2 WHERE AND WHY MOLD GROWS 

Lesson 4 Ventilation Humidity Problems - Heating, Ventilation, and Air Conditioning (HVAC) System 

QUESTION 5 

If duct work insulation becomes contaminated with mold, the insulation must be removed and replaced. 

Please click on your answer. 

• True 

• False 
56 

MOLD REMEDIATION KNOWLEDGE TEST

Chapter 2 WHERE AND WHY MOLD GROWS 

Lesson 4 Ventilation Humidity Problems - Heating, Ventilation, and Air Conditioning (HVAC) System 

QUESTION 5 

If duct work insulation becomes contaminated with mold, the insulation must be removed and replaced. 

Please click on your answer. 

• True 

• False 

The correct answer is "True." 

This topic was covered in Chapter 2, Lesson 4. 
57 

MOLD REMEDIATION KNOWLEDGE TEST

Chapter 2 WHERE AND WHY MOLD GROWS 

Lesson 4 Ventilation Humidity Problems - Heating, Ventilation, and Air Conditioning (HVAC) System 

QUESTION 6 

Drain pans should be sealed so that water does not get out. 

Please click on your answer. 

• True 

• False 

 
58 

MOLD REMEDIATION KNOWLEDGE TEST

Chapter 2 WHERE AND WHY MOLD GROWS 

Lesson 4 Ventilation Humidity Problems - Heating, Ventilation, and Air Conditioning (HVAC) System 

QUESTION 6 

Drain pans should be sealed so that water does not get out. 

Please click on your answer. 

• True 

• False 

 

The correct answer is "False." 

This topic was covered in Chapter 2, Lesson 4. 
59 

MOLD REMEDIATION KNOWLEDGE TEST

Chapter 2 WHERE AND WHY MOLD GROWS 

Lesson 5 Structural Integrity and Mold Growth 

QUESTION 7 

Mold can cause cosmetic damage to building furnishings. 

Please click on your answer. 

• True 

• False 
60 

MOLD REMEDIATION KNOWLEDGE TEST

Chapter 2 WHERE AND WHY MOLD GROWS 

Lesson 5 Structural Integrity and Mold Growth 

QUESTION 7 

Mold can cause cosmetic damage to building furnishings. 

Please click on your answer. 

• True 

• False 

The correct answer is "True." 

This topic was covered in Chapter 2, Lesson 5. 
61 

MOLD REMEDIATION KNOWLEDGE TEST

Chapter 2 WHERE AND WHY MOLD GROWS 

Lesson 5 Structural Integrity and Mold Growth 

QUESTION 8 

Evaluating the damage to a building done by mold never requires special expertise. 

Please click on your answer. 

• True 

• False 
62 

MOLD REMEDIATION KNOWLEDGE TEST

Chapter 2 WHERE AND WHY MOLD GROWS 

Lesson 5 Structural Integrity and Mold Growth 

QUESTION 8 

Evaluating the damage to a building done by mold never requires special expertise. 

Please click on your answer. 

• True 

• False 

The correct answer is "False." 

This topic was covered in Chapter 2, Lesson 5. 
63 

MOLD REMEDIATION KNOWLEDGE TEST

Chapter 2 WHERE AND WHY MOLD GROWS 

Lesson 6 Crawl Spaces 

QUESTION 9 

Mold will not grow in crawl spaces. 

Please click on your answer. 

• True 

• False 
64 

MOLD REMEDIATION KNOWLEDGE TEST

Chapter 2 WHERE AND WHY MOLD GROWS 

Lesson 6 Crawl Spaces 

QUESTION 9 

Mold will not grow in crawl spaces. 

Please click on your answer. 

• True 

• False 

The correct answer is "False." 

This topic was covered in Chapter 2, Lesson 6. 
65 

CHAPTER 3

FINDING MOLD AND MOISTURE 

Lesson 1 Where to Look for Mold Contamination - Building Investigation

As discussed in Chapter 2, mold can grow in wet or damp spots in a building, or where 

humidity is high. Therefore, it is important to look for indoor areas where moisture is a 

concern. Chapter 2 lists a number of factors that may contribute to indoor humidity and 

moisture problems. Reports of any of these problems should be investigated. If there has 

been a leaking pipe in the basement, for example, items such as carpets, paneling, and 

drywall there should be checked for water damage or mold growth. It is important to dry 

items quickly to prevent mold growth; in most cases, items dried within 24-48 hours will 

not become moldy. 

Carpet

Carpet backing or padding must be dried in addition to the carpet or mold will likely result. 

Look for mold in wet or damp places and in places that smell moldy or musty. 

Indoor mold growth should be cleaned up. Remember that mold comes in many 

colors, not just black. 

Hidden Mold Growth

In some cases, indoor mold growth may not be obvious. Mold does not need light to 

grow: it can grow in dark areas and on hidden surfaces, such as the backside of 

drywall, wallpaper, and paneling; the top side of ceiling tiles; and the underside of 

carpets and pads. Possible locations of hidden mold also include damp areas behind 

walls and in crawlspaces, inside pipe chases and utility tunnels (areas in walls where 

water and other pipes are run), on acoustic liners in ventilation ducts, and on roof 

materials above ceiling tiles. 

Investigating hidden mold can be difficult and may require a professional with experience investigating waterand mold-damaged buildings. Specialized equipment such as borescopes and moisture meters, and in some 

cases special sampling techniques, may be helpful in locating and identifying hidden mold areas. 

Investigating hidden mold requires caution since disturbing moldy areas may spread mold throughout the 

building. Opening and closing air handlers, for example, can send high levels of dust and mold into the air. 

Personal protective equipment (PPE) is not always needed when looking for mold, but it should always be 

available. If mold might be released into the air, investigators should use PPE to reduce exposure. 

Homes

Areas that are always or often damp, such as bathrooms, laundry/utility rooms, and 

basements, are common locations for mold growth in homes. Regularly check areas 

that have been or are likely to get wet. If you hire a home inspector, building 

inspector, or other professional to locate a water or mold problem, make sure the 

professional has experience identifying and locating mold and water problems. Check 

references and look for membership in professional organizations. 

Commercial Buildings, Large Buildings, and Schools

A key step when looking for mold in a building is to determine whether there has been a water leak. 

Maintenance personnel are frequently among the first to know when moisture problems have occurred. In 

some cases, management or health and safety personnel will have been notified. Either way, touring the 

building with maintenance or other personnel involved with the water problem may be helpful. 
66 

If possible, crawl spaces should be included when examining the building. (A white, soluble fibrous material 

on the soil of the crawl space may be alkaline salts, not mold, indicating moisture has been a problem and 

suggesting that the area should be more extensively inspected.) 

Moldy or musty odors should alert an investigator to the possible presence of mold. Complaints of past water 

problems or water leaks should be investigated to determine how much water was involved and how quickly 

it was removed. 

The building's air-handling system should be inspected to determine whether it is moldy. Moisture may 

collect in the ventilation system due to poor condensate pan drainage, poor roof drainage, or high humidity in 

the ventilation ducts. In some cases, water may enter the ventilation ducts from a leaky pipe. A contaminated 

ventilation system may spread mold spores throughout the building and should be considered a high priority 

for investigation and repair. Ventilation system mold contamination should be mitigated as soon as possible 

in a manner that does not expose building occupants to dust and mold spores. (See Chapter 6.) 

During the building survey, any moldy or damp odors should be noted because damp or musty odors 

suggest that water is or was present and mold growth is likely. Occupant complaints of odors and health 

problems also should be investigated. 
67 

CHAPTER 3

FINDING MOLD AND MOISTURE 

Lesson 2 Equipment

In general, the most important equipment is your own eyes and nose, although a good flashlight may help. 

Some investigators use borescopes to look for mold growth behind walls without significantly damaging the 

drywall. (A borescope is an optical probe, inserted through a small hole drilled into a wall, that lets an 

investigator inspect a small portion of the wall without causing extensive damage.) High humidity in a 

building can lead to mold growth, so humidity gauges may be useful for checking or monitoring humidity 

throughout the building. 

Many investigators use moisture meters to find wet areas where mold may be growing. 

These meters measure the moisture in many types of building materials. They also can 

monitor the process of drying these materials. A moisture meter typically has a thin probe 

that can be inserted into the material to be tested or pressed directly against its surface. 

Moisture meters can be used on carpet, wallboard, wood, brick, and concrete. Because 

mold often grows where moisture is high, a moisture meter can help an investigator 

locate hidden areas of mold growth. 

The use of personal protective equipment (PPE) should be considered during a mold 

investigation. The primary function of PPE is to avoid inhaling mold and mold spores and to avoid mold 

contact with the skin and eyes. Professional judgment should be used when selecting PPE. (See Table 1 for 

more on PPE. ) The use of PPE is indicated when mold is disturbed and likely to become airborne during an 

investigation. There are also other situations when PPE should be used based on professional judgment. 

Anyone using respirators and other PPE in the workplace must be trained, must have a medical clearance, 

and must be fit-tested by a trained professional. Note that all Occupational Safety and Health Administration 

(OSHA) requirements must be met. (See the Resource List.) 
68 

CHAPTER 3

FINDING MOLD AND MOISTURE 

Lesson 3 Mold Sampling Considered

Visible Mold 

In most cases, if visible mold is present, sampling is unnecessary.

The most important sign of a mold problem is visible mold. If mold is found during a building investigation, 

the size and extent of the moldy area should be determined. Information on the water or moisture problems 

that allowed the mold to grow should be evaluated, in part because areas of hidden mold may surround the 

areas of visible mold. 

Is sampling for mold needed? Usually, if the mold can be seen, sampling is unnecessary. 

After finding mold, the goal is to clean it up and fix the underlying water problem. Unless 

the results would or could make a change in your plans, you don't need to sample. Under 

certain circumstances, such as when litigation is involved, the source of the mold is 

unclear, or health concerns are a problem, you may consider sampling as part of your 

site evaluation. However, routine sampling for mold is not recommended. Keep in mind 

that the goal of mold remediation is to find the source of the water problem, fix it, and 

clean up the mold. 

Sampling may help locate the source of mold contamination, identify some of the mold 

species present, and differentiate between mold and soot or dirt. Surface sampling may 

be useful in determining if an area has been adequately cleaned or remediated. After 

remediation, the types and concentrations of mold in indoor air samples should be similar 

to those in the local outdoor air. There are no EPA or other federal standards for airborne 

mold or mold spores, however, so sampling cannot be used to check a building's 

compliance with federal mold standards because there are none. 

Sampling for mold should be conducted by professionals who have specific experience in 

designing mold sampling protocols, sampling methods, and interpreting the results. Several problems can 

occur when sampling. For example, there may be too few samples, sampling protocols may not be followed 

consistently, samples may become contaminated, outdoor control samples may be omitted, and since 

sampling can be expensive, sufficient funds may not be available to sample and to fix the water/mold 

problem. Professional advice may be necessary to determine if the project budget will allow enough samples 

to be taken to characterize a problem. If sampling cannot be done properly and enough samples to answer 

the questions posed cannot be taken, then it is preferable not to sample at all. Inadequate sample plans may 

generate misleading, confusing, and useless results. Samples should be analyzed according to the analytical 

methods recommended by the American Industrial Hygiene Association (AIHA), the American Conference of 

Governmental Industrial Hygienists (ACGIH), or other professional guidelines. (See the Resource List.) 

Types of samples include air samples, surface samples, bulk samples (chunks of carpet, insulation, wall 

board, etc.), and water samples from condensate drain pans or cooling towers. Keep in mind that air 

sampling for mold provides information only for the moment when the sampling took place. For someone 

without experience, sampling results will be difficult to interpret. Experience in interpreting results is 

essential. 

Mold Versus Soot and Dirt 

Not everything that looks like mold is mold. Paint on the backside of drywall or wood may look like mold 

growth. Alkaline crystals on soil or concrete walls may look like mold, but, unlike mold, they are usually 

water-soluble. Carpet stains also may look like mold. 
69 

Some inexpensive and quick tests can be conducted if mold is suspected. In the case 

of carpets, a small portion of the suspect material can be submitted to a laboratory for 

identification. Most microbiology laboratories need only a little of the suspected mold 

on a clear strip of sticky tape to determine, using a microscope, whether it is actually 

mold or something that looks like mold. If you lack extensive experience or are in doubt 

about sampling, consult an experienced professional. Remember, sampling results 

may have limited use or application. 

 
70 

MOLD REMEDIATION KNOWLEDGE TEST

Chapter 3 FINDING MOLD AND MOISTURE 

Lesson 1 Where to Look for Mold Contamination - Building Investigation 

QUESTION 1 

Mold can grow on wet carpet and wet carpet backing or padding if they are not dried quickly. 

Please click on your answer. 

• True 

• False 
71 

MOLD REMEDIATION KNOWLEDGE TEST

Chapter 3 FINDING MOLD AND MOISTURE 

Lesson 1 Where to Look for Mold Contamination - Building Investigation 

QUESTION 1 

Mold can grow on wet carpet and wet carpet backing or padding if they are not dried quickly. 

Please click on your answer. 

• True 

• False 

The correct answer is "True." 

This topic was covered in Chapter 3, Lesson 1. 
72 

MOLD REMEDIATION KNOWLEDGE TEST

Chapter 3 FINDING MOLD AND MOISTURE 

Lesson 1 Where to Look for Mold Contamination - Building Investigation 

QUESTION 2 

In which of the following areas of a building may mold problems be found? 

Please click on your answer. 

• A. The crawlspace 

• B. In pipe chases 

• C. Behind walls 

• D. All of the above 
73 

MOLD REMEDIATION KNOWLEDGE TEST

Chapter 3 FINDING MOLD AND MOISTURE 

Lesson 1 Where to Look for Mold Contamination - Building Investigation 

QUESTION 2 

In which of the following areas of a building may mold problems be found? 

Please click on your answer. 

• A. The crawlspace 

• B. In pipe chases 

• C. Behind walls 

• D. All of the above 

The correct answer is D. 

This topic was covered in Chapter 3, Lesson 1. 
74 

MOLD REMEDIATION KNOWLEDGE TEST

Chapter 3 FINDING MOLD AND MOISTURE 

Lesson 1 Where to Look for Mold Contamination - Building Investigation 

QUESTION 3 

A contaminated ventilation system (HVAC system) may spread mold throughout the building. 

Please click on your answer. 

• True 

• False 
75 

MOLD REMEDIATION KNOWLEDGE TEST

Chapter 3 FINDING MOLD AND MOISTURE 

Lesson 1 Where to Look for Mold Contamination - Building Investigation 

QUESTION 3 

A contaminated ventilation system (HVAC system) may spread mold throughout the building. 

Please click on your answer. 

• True 

• False 

The correct answer is "True." 

This topic was covered in Chapter 3, Lesson 1. 
76 

MOLD REMEDIATION KNOWLEDGE TEST

Chapter 3 FINDING MOLD AND MOISTURE 

Lesson 2 Equipment 

QUESTION 4 

Moisture meters can be used to monitor the process of drying. 

Please click on your answer. 

• True 

• False 
77 

MOLD REMEDIATION KNOWLEDGE TEST

Chapter 3 FINDING MOLD AND MOISTURE 

Lesson 2 Equipment 

QUESTION 4 

Moisture meters can be used to monitor the process of drying. 

Please click on your answer. 

• True 

• False 

The correct answer is "True." 

This topic was covered in Chapter 3, Lesson 2. 
78 

MOLD REMEDIATION KNOWLEDGE TEST

Chapter 3 FINDING MOLD AND MOISTURE 

Lesson 2 Equipment 

QUESTION 5 

Personal protective equipment(PPE) is never needed for mold investigations. 

Please click on your answer. 

• True 

• False 
79 

MOLD REMEDIATION KNOWLEDGE TEST

Chapter 3 FINDING MOLD AND MOISTURE 

Lesson 2 Equipment 

QUESTION 5 

Personal protective equipment(PPE) is never needed for mold investigations. 

Please click on your answer. 

• True 

• False 

The correct answer is "False." 

This topic was covered in Chapter 3, Lesson 2. 
80 

MOLD REMEDIATION KNOWLEDGE TEST

Chapter 3 FINDING MOLD AND MOISTURE 

Lesson 3 Mold Sampling Considered 

QUESTION 6 

Mold sampling should be conducted whenever a mold remediation is planned. 

Please click on your answer. 

• True 

• False 
81 

MOLD REMEDIATION KNOWLEDGE TEST

Chapter 3 FINDING MOLD AND MOISTURE 

Lesson 3 Mold Sampling Considered 

QUESTION 6 

Mold sampling should be conducted whenever a mold remediation is planned. 

Please click on your answer. 

• True 

• False 

The correct answer is "False." 

This topic was covered in Chapter 3, Lesson 3. 
82 

CHAPTER 4

GENERAL REMEDIATION ISSUES 

Lesson 1 Dry Quickly

Dry items before mold grows, if possible. In most cases, mold will not grow if wet or damp items are 

dried within 24-48 hours. 

To dry carpet and backing within 48 hours, remove water with a wet vacuum, pull the carpet and pad off the 

floor, and dry them using a fan to blow air over them. A dehumidifier can be used to reduce the humidity in 

the room where the carpet and backing are drying, while fans can be used to accelerate the drying process. 

Water can be removed from concrete or cinder block surfaces with a water-extraction vacuum. The drying 

also can be accelerated by using dehumidifiers, fans, and heaters. 

Hard surface flooring (such as linoleum, ceramic tile, and vinyl) should be vacuumed or damp wiped 

with a mild detergent and allowed to dry. They should be scrubbed clean, if necessary. If the under-flooring is 

wet, it should be dried using a vacuum or by exposing it to the air. 

Non-porous, hard surfaces such as plastics and metals should be vacuumed or damp wiped with water 

and mild detergent, then allowed to dry. Scrubbing may be necessary to thoroughly clean the surfaces. 

Water should be removed from upholstered furniture with a water-extraction vacuum. Fans, dehumidifiers, 

and heaters may be used to accelerate the drying process. Completely drying upholstered furniture within 48 

hours may be difficult, so if the piece is valuable, you may consider consulting a restoration or water-damage 

professional who specializes in furniture. 

Drywall, also known as gypsum board or gypsum wallboard, may be dried in place if there is no obvious 

swelling and the seams are intact. Otherwise, removal is necessary. The wall cavity is the most difficult area 

to dry, and it should be ventilated if drywall is left to dry in place. (Drywall is not made out of boards of wood; 

traditionally, drywall is made of the mineral gypsum with a layer of heavy paper on the outside and inside. 

Commercial gypsum boards and drywall are also available with a variety of outside layers and coatings. 

According to the U.S. Geological Survey, a typical new home contains more than 7 metric tons of gypsum.) 

To clean water-damaged window drapes, follow the manufacturer's laundering or cleaning instructions. 

To clean wooden surfaces, remove moisture immediately and use dehumidifiers, fans, and gentle heat to 

dry them. (Be very careful when applying heat to hardwood floors.) Treated or finished wood surfaces can 

be cleaned with mild detergent and clean water, then allowed to dry. Wet paneling should be pried from the 

wall for drying. 

Some water-damaged items, including ceiling tiles, cellulose and fiberglass insulation, drywall and gypsum 

board, and books and papers, may have to be discarded. If valuable or important books, documents, or other 

items are moldy or water damaged, you may wish to consult a restoration, water damage, or remediation 

expert. (See Table 1 for more details. ) 

These guidelines are for damage caused by clean water. If you know or suspect that the water is 

contaminated with sewage, or with chemical or biological pollutants, then PPE and containment are required 

by OSHA. An experienced professional should be consulted if you or your remediators do not have expertise 

remediating in contaminated water situations. Do not use fans until you have determined that the water is 

clean or sanitary. 
83 

CHAPTER 4

GENERAL REMEDIATION ISSUES 

Lesson 2 Assess Mold Problem

Before planning a remediation effort, the size and extent of the mold problem and any 

continuing moisture problems should be assessed. Remediations generally can be 

divided into small (less than 10 square feet of mold), medium (10-100 square feet of 

mold), and large jobs (more than 100 square feet of mold). A remediation manager 

should be selected for medium or large jobs. You may choose to involve an experienced 

health and safety professional in remediation projects, particularly on large or complex 

jobs. 

Questions to consider before starting remediation include: 

• Are there existing moisture problems in the building? 

• Have building materials been wet more than 48 hours? 

• Are there hidden sources of water, or is the humidity high enough to cause condensation? 

• Are the building occupants reporting musty or moldy odors? 

• Are the building occupants reporting health problems? 

• Are building materials or furnishings visibly damaged? 

• Has maintenance been delayed or has the maintenance plan been altered? 

• Has the building been remodeled recently, or has its use changed? 

• Are consultations with health professionals indicated? 

Remediating mold and moisture problems may be complex, and it may increase workers' exposure to mold 

unless personal protective equipment (PPE) is used. 

Avoid Mold Exposure

Do not touch mold or moldy items with your bare hands. 

Do not get mold or mold spores in your eyes. 

Avoid breathing in mold or mold spores. 

Consider using PPE if disturbing mold during a building inspection, assessment, 

or walkthrough, for example. The minimum PPE is an N-95 respirator (available 

at most hardware stores), gloves, and goggles. 

Review guidelines for using containment and PPE before starting remediation. 

(see Table 2) 

Remediation workers, especially if they have health concerns, may want to check with their doctors before 

working on a mold investigation or remediation project. Anyone who has any doubts or questions should 

consult a healthcare professional before beginning work on a remediation project. See Chapter 6, Lesson 4, 

for more information on PPE. 
84 

CHAPTER 4

GENERAL REMEDIATION ISSUES 

Lesson 3 Remediation Plan

The highest priority in a remediation is to protect the health and safety of the building occupants and the 

remediation workers. Remediation plans vary according to the size and complexity of the job. They may 

require updating if circumstances change or more extensive contamination is discovered. 

The remediation plan should include: 

Whether containment will be required. 

What level of PPE will be used. 

How the water or moisture problem will be fixed so the mold problem does not recur. 

How the moldy building materials will be removed to avoid spreading mold. 
85 

CHAPTER 4

GENERAL REMEDIATION ISSUES 

Lesson 4 Mold Remediation Procedures

A variety of methods are available to remediate damage to buildings and furnishings caused by moisturecontrol problems and mold. The procedures selected depend on the size of the moldy area and the type of 

contaminated materials. Budget may also be a concern. The methods presented in this section outline one 

approach; some professionals may prefer to use other methods. If possible, remediation activities should be 

scheduled during off-hours, when building occupants are less likely to be affected. 

Cleanup methods may include: 

Wet Vacuum

Wet, or water-extraction, vacuums are designed to collect water. They can be used to remove water that 

has accumulated on floors, carpets, and hard surfaces. Wet vacuums should be used only when materials 

are still wet, otherwise they may spread mold spores. Wet vacuums alone will not dry carpets. Wet carpets 

must be pulled up and dried, then reinstalled. The carpet padding also must be dried. The tanks, hoses, and 

attachments of wet vacuums should be thoroughly cleaned and dried after use because mold and mold 

spores may stick to their surfaces. 

Damp Wipe

Mold can generally be removed from hard surfaces by wiping or scrubbing with water and 

detergent. Always follow the cleaning instructions on product labels. Surfaces cleaned by 

damp wiping should be dried quickly and thoroughly to discourage further mold growth. 

Porous materials that are wet and have mold growing on them may have to be discarded. 

Because mold will infiltrate porous substances and grow on or fill in empty spaces or 

crevices, completely removing mold can be difficult, if not impossible. Mold can also 

cause staining and other cosmetic damage. 

HEPA Vacuum

High-Efficiency Particulate Air (HEPA) vacuums are recommended for the final clean 

up of remediation areas after materials have been thoroughly dried and contaminated 

materials have been removed. HEPA vacuums are also recommended for cleaning up 

dust that has settled outside the remediation area. When changing the vacuum filter, 

workers should wear PPE to prevent exposure to mold that has been captured in the 

vacuum. (See Lesson 4 in Chapter 6 of this course.) The filter and contents of the HEPA 

vacuum must be disposed of in well-sealed plastic bags. Care must be taken to ensure 

that the new filter is properly seated on the vacuum so there are no leaks. 

Throw Away Damaged Materials

Mold-contaminated building materials that cannot be salvaged should be double-bagged in 6-mil or thicker 

polyethylene bags. The bagged materials usually can be discarded as ordinary construction waste. 

Packaging mold-contaminated materials in sealed bags before removing them from the containment area is 

important to minimize the spread of mold spores throughout the building. Large items that have heavy mold 

growth should be covered with polyethylene sheeting and sealed with duct tape before being removed from 

the containment area. 
86 

Table 1: Water Damage - Cleanup and Mold Prevention

Guidelines for Response to Clean Water Damage within 24-48 Hours to Prevent Mold Growth* 

Water-Damaged 

Material†

Actions

Books and papers • For non-valuable items, discard books and papers. 

• Photocopy valuable/important items, discard originals. 

• Freeze (in frost-free freezer or meat locker) or freeze-dry. 

Carpet and 

backing - dry 

within 24-48 

hours§

• Remove water with water extraction vacuum. 

• Reduce ambient humidity levels with dehumidifier. 

• Accelerate drying process with fans. 

Ceiling tiles • Discard and replace. 

Cellulose 

insulation

• Discard and replace. 

Concrete or 

cinder block 

surfaces

• Remove water with water extraction vacuum. 

• Accelerate drying process with dehumidifiers, fans, and/or heaters. 

Fiberglass 

insulation

• Discard and replace. 

Hard surface, 

porous flooring§

(Linoleum, ceramic 

tile, vinyl) 

• Vacuum or damp wipe with water and mild detergent and allow to dry; 

scrub if necessary. 

• Check to make sure underflooring is dry; dry underflooring if necessary. 

Non-porous, hard 

surfaces 

(Plastics, metals) 

• Vacuum or damp wipe with water and mild detergent and allow to dry; 

scrub if necessary. 

Upholstered 

furniture

• Remove water with water extraction vacuum. 

• Accelerate drying process with dehumidifiers, fans, and/or heaters. 

• May be difficult to completely dry within 48 hours. If the piece is valuable, 

you may wish to consult a restoration/water damage professional who 

specializes in furniture. 

Wallboard

(Drywall and 

gypsum board) 

• May be dried in place if there is no obvious swelling and the seams are 

intact. If not, remove, discard, and replace. 

• Ventilate the wall cavity, if possible. 

Window drapes • Follow laundering or cleaning instructions recommended by the 

manufacturer. 

Wood surfaces • Remove moisture immediately and use dehumidifiers, gentle heat, and 

fans for drying. (Use caution when applying heat to hardwood floors.) 
87 

• Treated or finished wood surfaces may be cleaned with mild detergent and 

clean water and allowed to dry. 

• Wet paneling should be pried away from wall for drying. 

* If mold growth has occurred or materials have been wet for more than 48 hours, consult Table 2 

guidelines. Even if materials are dried within 48 hours, mold growth may have occurred. Items may be 

tested by professionals if there is doubt. Note that mold growth will not always occur after 48 hours; this 

is only a guideline. 

These guidelines are for damage caused by clean water. If you know or suspect that the water source is 

contaminated with sewage, or chemical or biological pollutants, then Personal Protective Equipment and 

containment are required by OSHA. An experienced professional should be consulted if you and/or your 

remediators do not have expertise remediating in contaminated water situations. Do not use fans before 

determining that the water is clean or sanitary. 

† If a particular item(s) has high monetary or sentimental value, you may wish to consult a 

restoration/water damage specialist. 

§ The subfloor under the carpet or other flooring material must also be cleaned and dried. See the 

appropriate section of this table for recommended actions depending on the composition of the subfloor. 
88 

Table 2: Guidelines for Remediating Building Materials with Mold Growth Caused by Clean 

Water* 

Material or Furnishing 

Affected 

Cleanup 

Methods† Personal Protective Equipment Containment 

SMALL - Total Surface Area Affected Less Than 10 square feet (ft2)

Books and papers 3 

Carpet and backing 1, 3 

Concrete or cinder 

block 1, 3 

Hard surface, porous 

flooring (linoleum, 

ceramic tile, vinyl) 

1, 2, 3 

Non-porous, hard 

surfaces (plastics, 

metals) 

1, 2, 3 

Upholstered furniture 

& drapes 1, 3 

Wallboard (drywall 

and gypsum board) 3 

Wood surfaces 1, 2, 3 

Minimum 

N-95 respirator, gloves, and 

goggles 

None required 

Material or Furnishing 

Affected 

Cleanup 

Methods† Personal Protective Equipment Containment 

MEDIUM - Total Surface Area Affected Between 10 and 100 (ft2)

Books and papers 3 

Carpet and backing 1,3,4 

Concrete or cinder 

block 1,3 

Hard surface, porous 

flooring (linoleum, 

ceramic tile, vinyl) 

1,2,3 

Non-porous, hard 

surfaces (plastics, 

metals) 

1,2,3 

Upholstered furniture 

& drapes 1,3,4 

Wallboard (drywall 

and gypsum board) 3,4 

Wood surfaces 1,2,3 

Limited or Full 

Use professional judgment, 

consider potential for remediator 

exposure and size of 

contaminated area 

 

Limited 

Use professional judgment, 

consider potential for 

remediator/occupant exposure 

and size of contaminated area 

 

Material or Furnishing 

Affected 

Cleanup 

Methods† Personal Protective Equipment Containment 

LARGE - Total Surface Area Affected Greater Than 100 (ft2) or Potential for 

Increased Occupant or Remediator Exposure During Remediation Estimated to be Significant
89 

Books and papers 3 

Carpet and backing 1,3,4 

Concrete or cinder 

block 1,3 

Hard surface, porous 

flooring (linoleum, 

ceramic tile, vinyl) 

1,2,3,4 

Non-porous, hard 

surfaces (plastics, 

metals) 

1,2,3 

Upholstered furniture 

& drapes 1,3,4 

Wallboard (drywall 

and gypsum board) 3,4 

Wood surfaces 1,2,3,4 

Full 

Use professional judgment, 

consider potential for remediator 

exposure and size of 

contaminated area 

 

Full 

Use professional judgment, 

consider potential for 

remediator/occupant exposure 

and size of contaminated area 

 

Table 1 continued 

*Use professional judgment to determine prudent levels of Personal Protective Equipment and 

containment for each situation, particularly as the remediation site size increases and the potential for 

exposure and health effects rises. Assess the need for increased Personal Protective Equipment, if, 

during the remediation, more extensive contamination is encountered than was expected. Consult Table 

1 if materials have been wet for less than 48 hours, and mold growth is not apparent. 

These guidelines are for damage caused by clean water. If you know or suspect that the water source is 

contaminated with sewage, or chemical or biological pollutants, then the Occupational Safety and Health 

Administration (OSHA) requires PPE and containment. An experienced professional should be consulted 

if you and/or your remediators do not have expertise in remediating contaminated water situations. 

†Select method most appropriate to situation. Since molds gradually destroy the things they grow on, if 

mold growth is not addressed promptly, some items may be damaged such that cleaning will not restore 

their original appearance. If mold growth is heavy and items are valuable or important, you may wish to 

consult a restoration/water damage/remediation expert. Please note that these are guidelines; other 

cleaning methods may be preferred by some professionals. 

Cleanup Methods 

• Method 1: Wet vacuum (in the case of porous materials, some mold spores/fragments will 

remain in the material but will not grow if the material is completely dried). Steam cleaning may 

be an alternative for carpets and some upholstered furniture. 

• Method 2: Damp-wipe surfaces with plain water or with water and detergent solution (except 

wood -use wood floor cleaner); scrub as needed. 

• Method 3: High-efficiency particulate air (HEPA) vacuum after the material has been thoroughly 

dried. Dispose of the contents of the HEPA vacuum in well-sealed plastic bags. 

• Method 4: Discard - remove water-damaged materials and seal in plastic bags while inside of 

containment, if present. Dispose of as normal waste. HEPA vacuum area after it is dried. 

Personal Protective Equipment (PPE) 

• Minimum: Gloves, N-95 respirator, goggles/eye protection 
90 

• Limited: Gloves, N-95 respirator or half-face respirator with HEPA filter, disposable overalls, 

goggles/eye protection 

• Full: Gloves, disposable full body clothing, head gear, foot coverings, full-face respirator with 

HEPA filter 

Containment 

• Limited: Use polyethylene sheeting ceiling to floor around affected area with a slit entry and 

covering flap; maintain area under negative pressure with HEPA filtered fan unit. Block supply 

and return air vents within containment area. 

• Full: Use two layers of fire-retardant polyethylene sheeting with one airlock chamber. Maintain 

area under negative pressure with HEPA filtered fan exhausted outside of building. Block supply 

and return air vents within containment area. 

Table developed from literature and remediation documents including Bioaerosols: Assessment and 

Control (American Conference of Governmental Industrial Hygienists, 1999) and IICRC S500, Standard 

and Reference Guide for Professional Water Damage Restoration (Institute of Inspection, Cleaning and 

Restoration, 1999); see the Resource List for more information. 
91 

MOLD REMEDIATION KNOWLEDGE TEST

GENERAL REMEDIATION ISSUES 

Lesson 1 Dry Quickly 

QUESTION 1 

Quick action to address a moisture problem may make an extensive mold remediation effort unnecessary. 

Please click on your answer. 

• True 

• False 
92 

MOLD REMEDIATION KNOWLEDGE TEST

GENERAL REMEDIATION ISSUES 

Lesson 1 Dry Quickly 

QUESTION 1 

Quick action to address a moisture problem may make an extensive mold remediation effort unnecessary. 

Please click on your answer. 

• True 

• False 

The correct answer is "True." 

This topic was covered in Chapter 4, Lesson 1. 
93 

MOLD REMEDIATION KNOWLEDGE TEST

GENERAL REMEDIATION ISSUES 

Lesson 1 Dry Quickly 

QUESTION 2 

Which of the following types of materials may have to be discarded when contaminated with mold or mold 

spores? 

Please click on your answer. 

• A. Hard surfaces such as linoleum or tile 

• B. Cellulose or fiberglass insulation 

• C. Plastics and metals 

• D. All of the above 
94 

MOLD REMEDIATION KNOWLEDGE TEST

GENERAL REMEDIATION ISSUES 

Lesson 1 Dry Quickly 

QUESTION 2 

Which of the following types of materials may have to be discarded when contaminated with mold or mold 

spores? 

Please click on your answer. 

• A. Hard surfaces such as linoleum or tile 

• B. Cellulose or fiberglass insulation 

• C. Plastics and metals 

• D. All of the above 

The correct answer is B. 

This topic was covered in Chapter 4, Lesson 1. 
95 

MOLD REMEDIATION KNOWLEDGE TEST

GENERAL REMEDIATION ISSUES 

Lesson 2 Assess Mold Problem 

QUESTION 3 

It is important to assess the size and extent of the mold problem before starting remediation. 

Please click on your answer. 

• True 

• False 
96 

MOLD REMEDIATION KNOWLEDGE TEST

GENERAL REMEDIATION ISSUES 

Lesson 2 Assess Mold Problem 

QUESTION 3 

It is important to assess the size and extent of the mold problem before starting remediation. 

Please click on your answer. 

• True 

• False 

The correct answer is "True." 

This topic was covered in Chapter 4, Lesson 2. 
97 

MOLD REMEDIATION KNOWLEDGE TEST

GENERAL REMEDIATION ISSUES 

Lesson 2 Assess Mold Problem 

QUESTION 4 

You should consider using personal protective equipment (PPE) if disturbing mold during a building 

assessment. 

Please click on your answer. 

• True 

• False 
98 

MOLD REMEDIATION KNOWLEDGE TEST

GENERAL REMEDIATION ISSUES 

Lesson 2 Assess Mold Problem 

QUESTION 4 

You should consider using personal protective equipment (PPE) if disturbing mold during a building 

assessment. 

Please click on your answer. 

• True 

• False 

The correct answer is "True." 

This topic was covered in Chapter 4, Lesson 2. 
99 

MOLD REMEDIATION KNOWLEDGE TEST

GENERAL REMEDIATION ISSUES 

Lesson 2 Assess Mold Problem 

QUESTION 5 

Minimum PPE includes: 

Please click on your answer. 

• A. N-95 respirator 

• B. Gloves 

• C. Hat 

• D. Goggles 

• E. A, B, and D 
100 

MOLD REMEDIATION KNOWLEDGE TEST

GENERAL REMEDIATION ISSUES 

Lesson 2 Assess Mold Problem 

QUESTION 5 

Minimum PPE includes: 

Please click on your answer. 

• A. N-95 respirator 

• B. Gloves 

• C. Hat 

• D. Goggles 

• E. A, B, and D 

The correct answer is E. 

This topic was covered in Chapter 4, Lesson 2. 
101 

MOLD REMEDIATION KNOWLEDGE TEST

GENERAL REMEDIATION ISSUES 

Lesson 3 Remediation Plan 

QUESTION 6 

A remediation plan should cover: 

Please click on your answer. 

• A. The containment and removal techniques to be used to avoid the spread of mold 

• B. The use of PPE 

• C. Steps to correct moisture or water problems in order to prevent the recurrence of mold 

• D. All of the above 
102 

MOLD REMEDIATION KNOWLEDGE TEST

GENERAL REMEDIATION ISSUES 

Lesson 3 Remediation Plan 

QUESTION 6 

A remediation plan should cover: 

Please click on your answer. 

• A. The containment and removal techniques to be used to avoid the spread of mold 

• B. The use of PPE 

• C. Steps to correct moisture or water problems in order to prevent the recurrence of mold 

• D. All of the above 

The correct answer is D. 

This topic was covered in Chapter 4, Lesson 3. 
103 

MOLD REMEDIATION KNOWLEDGE TEST

GENERAL REMEDIATION ISSUES 

Lesson 4 Mold Remediation Procedures 

QUESTION 7 

Professionals agree that there is only one acceptable method for remediating mold problems. 

Please click on your answer. 

• True 

• False 
104 

MOLD REMEDIATION KNOWLEDGE TEST

GENERAL REMEDIATION ISSUES 

Lesson 4 Mold Remediation Procedures 

QUESTION 7 

Professionals agree that there is only one acceptable method for remediating mold problems. 

Please click on your answer. 

• True 

• False 

The correct answer is "False." 

This topic was covered in Chapter 4, Lesson 4. 
105 

MOLD REMEDIATION KNOWLEDGE TEST

GENERAL REMEDIATION ISSUES 

Lesson 4 Mold Remediation Procedures 

QUESTION 8 

Remediation and cleanup activities should be scheduled for off-hours, when building occupants are less 

likely to be affected. 

Please click on your answer. 

• True 

• False 

 
106 

MOLD REMEDIATION KNOWLEDGE TEST

GENERAL REMEDIATION ISSUES 

Lesson 4 Mold Remediation Procedures 

QUESTION 8 

Remediation and cleanup activities should be scheduled for off-hours, when building occupants are less 

likely to be affected. 

Please click on your answer. 

• True 

• False 

The correct answer is "True." 

This topic was covered in Chapter 4, Lesson 3. 
107 

CHAPTER 5

LARGE AREAS AND OTHER SPECIAL CONCERNS 

Lesson 1 Remediating Large Areas of Mold Contamination

For large or complex mold remediation jobs, you may consider hiring professionals who have experience 

working on large mold remediation projects, particularly since extensive containment and PPE may be 

needed. Be sure to check references and ensure that the professional has experience working in mold 

remediation situations. Remediators should follow EPA mold remediation guidance or other government or 

professional remediation guidance. Building occupants need to be informed about what is going to happen, 

when it will happen, and how they may be affected. 

Containment should be designed to prevent the movement of mold spores from one area 

of the building to another. This effort usually requires full containment using double layers 

of polyethylene sheeting and fans to create negative air pressure. A decontamination 

chamber or airlock should be used to separate the clean areas from the contaminated 

areas during entry into and exit from the remediation area. The entryways to the airlock 

from the outside and from the airlock to the main containment area should consist of a slit 

with covering flaps on the outside surface of each entry. Contaminated PPE, except 

respirators, should be sealed in bags while inside the containment exit chamber. Workers 

should wear respirators until they are in the uncontaminated area, where the respirators 

can be removed. Disposable respirators can be thrown away and re-usable respirators can be put into a bag 

for cleaning. Full PPE may also be necessary during these operations and may consist of protective clothing 

and full-face or powered air purifying respirators (PAPR) with HEPA filters. Protective clothing should include 

head and foot coverings with all gaps sealed with duct tape or the equivalent. 
108 

CHAPTER 5

LARGE AREAS AND OTHER SPECIAL CONCERNS 

Lesson 2 Mold Remediation in Heating, Ventilation, and Air Conditioning 

(HVAC) Systems

Mold remediation involving a heating, ventilation, and air conditioning (HVAC) system should be done only 

by professionals experienced in working with HVAC systems. Professionals may have several different 

methods and techniques for approaching HVAC remediation. As with the rest of a mold remediation project, 

professional judgment is required when working with HVAC systems, and professionals may use materials, 

methods, and techniques not mentioned in this course. 

An HVAC system found to be contaminated with mold should be turned off and not used until the system has 

been remediated; using a mold-contaminated HVAC system may spread mold throughout the building and 

increase the exposure of building occupants. (There may be some exceptions or instances when all or part 

or the HVAC system can be run, based on professional judgment, if there is no risk of increasing occupant or 

worker exposure). If possible, the HVAC system should be remediated during off hours when the building is 

not in use. 

Effective containment of the area served by the ventilation system is important to avoid the spread of mold 

and mold-contaminated materials. All intakes and supply vents should be sealed with plastic and tape, and 

negative air pressure should be maintained in work areas. (A fan can be used.) Contaminated porous 

materials in the HVAC system should be bagged and removed. Materials that can be cleaned should be 

vacuumed with a HEPA vacuum or cleaned with a moist cloth and detergent solution. All items should be 

dried promptly. 

If you consider duct cleaning, first consult EPA's guide Should You Have the Air Ducts in Your Home 

Cleaned? (See the Resource List.) 
109 

CHAPTER 5

LARGE AREAS AND OTHER SPECIAL CONCERNS 

Lesson 3 Confined Spaces

Confined spaces include pipe chases (areas within and under buildings where steam and utility pipes are 

run) and valve pits (areas below grade that contain utility shut-off valves). Working in confined areas 

presents numerous challenges. Movement and communication are difficult and, if a problem arises, 

immediate exit from the area may be impossible. 

The air in some confined spaces may be contaminated or low in oxygen, posing significant health risks for 

workers. Efficient rescue of an injured worker may be difficult or impossible. Poor lighting may result in 

increased injuries. Because exposures may be greatly magnified in a confined space, workers must use a 

higher level of PPE than they would when working in a more accessible area. 

Worker safety must be carefully considered when deciding whether to use disinfectants or biocides because 

confined spaces may increase the potential for exposure. In general, work in confined spaces should be 

conducted only by trained professionals who have the equipment required by OSHA to deal with the inherent 

dangers in this type of environment. 

Before remediating mold in a confined space, the area should be evaluated for atmosphere and toxic 

substances. If there is any chance of low oxygen, the area should be tested using the appropriate 

equipment. The testing equipment should be kept on site and used periodically to ensure an adequate 

oxygen supply. If the area is sealed off from the rest of the building to prevent the spread of mold spores, 

oxygen testing should be conducted again after the area has been sealed. A frequent contaminant in 

crawlspaces and pipe chases of older buildings is asbestos; other chemicals such as natural gas and 

solvents can also be found in some of these spaces. These materials must be identified and dealt with 

properly to prevent worker exposure. 

Once the hazards have been identified, procedures for working in the confined space should be included in 

the remediation plan. Special consideration should be given to who will be allowed into the area, how 

communications will be maintained, what materials can be taken into or used in the space, and what safety 

equipment is necessary. Only individuals trained in the hazards associated with that space should be 

allowed to enter. An attendant should be posted outside of the confined space area to summon help if 

necessary. The area should be well lit so that work can be conducted efficiently and injuries avoided. 

In conducting the mold remediation, every effort should be made to keep dust and mold out of the air. This 

can be done by using moist techniques, such as a damp cloth or pad, for mold removal and by bagging the 

material in the confined space for later removal. Mold levels are likely to be high in a confined space, so PPE 

should be selected accordingly. Most cases will require full PPE, including skin and eye protection, and full 

respiratory protection using a full-face respirator or a powered air purifying respirator (PAPR) with a HEPA 

filter. The presence of asbestos may require other PPE for workers as well as monitoring and medical 

evaluation. 
110 

MOLD REMEDIATION KNOWLEDGE TEST

Chapter 5 LARGE AREAS AND OTHER SPECIAL CONCERNS 

Lesson 1 Remediating Large Areas of Mold Contamination 

QUESTION 1 

Full containment requires: 

Please click on your answer. 

• A. Double-layer polyethylene sheeting 

• B. A decontamination chamber 

• C. Respirators to be worn inside the containment area 

• D. All of the above 
111 

MOLD REMEDIATION KNOWLEDGE TEST

Chapter 5 LARGE AREAS AND OTHER SPECIAL CONCERNS 

Lesson 1 Remediating Large Areas of Mold Contamination 

QUESTION 1 

Full containment requires: 

Please click on your answer. 

• A. Double-layer polyethylene sheeting 

• B. A decontamination chamber 

• C. Respirators to be worn inside the containment area 

• D. All of the above 

The correct answer is D. 

This topic was covered in Chapter 5, Lesson 1. 
112 

MOLD REMEDIATION KNOWLEDGE TEST

Chapter 5 LARGE AREAS AND OTHER SPECIAL CONCERNS 

Lesson 2 Mold Remediation in Heating, Ventilation, Air Conditioning (HVAC) Systems 

QUESTION 2 

Mold-contaminated HVAC systems should be assessed by professionals. 

Please click on your answer. 

• True 

• False 
113 

MOLD REMEDIATION KNOWLEDGE TEST

Chapter 5 LARGE AREAS AND OTHER SPECIAL CONCERNS 

Lesson 2 Mold Remediation in Heating, Ventilation, Air Conditioning (HVAC) Systems 

QUESTION 2 

Mold-contaminated HVAC systems should be assessed by professionals. 

Please click on your answer. 

• True 

• False 

The correct answer is "True." 

This topic was covered in Chapter 5, Lesson 2. 
114 

MOLD REMEDIATION KNOWLEDGE TEST

Chapter 5 LARGE AREAS AND OTHER SPECIAL CONCERNS 

Lesson 3 Confined Spaces 

QUESTION 3 

Remediation projects in confined spaces require increased worker training to prevent problems due to poor 

lighting, communication, and mobility in the space. 

Please click on your answer. 

• True 

• False 
115 

MOLD REMEDIATION KNOWLEDGE TEST

Chapter 5 LARGE AREAS AND OTHER SPECIAL CONCERNS 

Lesson 3 Confined Spaces 

QUESTION 3 

Remediation projects in confined spaces require increased worker training to prevent problems due to poor 

lighting, communication, and mobility in the space. 

Please click on your answer. 

• True 

• False 

The correct answer is "True." 

This topic was covered in Chapter 5, Lesson 3. 
116 

CHAPTER 6

CONTAINMENT AND PERSONAL PROTECTIVE EQUIPMENT (PPE) 

Lesson 1 Overview of Containment

The goal of containment is to limit the spread of mold throughout the building in order to minimize the 

exposure of remediators and building occupants to mold. 

The larger the contaminated area, and the greater the possibility that someone will be exposed to mold, the 

greater the need for containment. Although, in general, the size of the contaminated area indicates the level 

of containment required, the final choice of containment level should be based on professional judgment. 

Heavy mold growth in a small area, for example, could release more mold spores than lighter growth in a 

relatively large area. In this case, the smaller contaminated area may warrant a higher level of containment. 

Two types of containment are described in EPA's mold remediation guidance: limited and full. Limited 

containment is generally used for areas involving between 10 and 100 square feet of mold contamination. 

Full containment is used when areas larger than 100 square feet are to be remediated or in cases where it is 

likely that mold could be spread throughout the building during remediation. (See Table 2. ) 

Maintaining the containment area under negative pressure will keep contaminated air 

from flowing into adjacent, uncontaminated areas and possibly spreading mold. A fan 

exhausted to the outside of the building can be used to maintain negative air pressure. If 

the containment is working, the polyethylene sheeting of the containment area should 

billow inward on all surfaces. If it flutters or billows outward, containment has been lost, 

and the problem should be found and corrected before remediation continues. 

Depending on the situation, professional remediators may choose to use a 

variety of containment methods not described in detail here. For example, a 

remediator repairing a large building with extensive mold damage in the walls 

may choose to remove the outside layer of the wall and work inward, relying on 

appropriate containment to ensure mold is not spread throughout the building. 

Or, to limit the amount of mold that gets into the air, a remediator may apply 

sticky-backed paper or covering to a moldy wall component before removing it. 
117 

CHAPTER 6

CONTAINMENT AND PERSONAL PROTECTIVE EQUIPMENT (PPE) 

Lesson 2 Limited Containment

Limited containment consists of a single layer of 6-mil fire-retardant polyethylene sheeting enclosing the 

moldy area. Access to the contained area is through a slit entry covered by a flap on the outside of the 

containment area. Limited containment is generally recommended for areas involving 10 to 100 square feet 

of mold contamination. 

In small areas, the polyethylene sheeting can be secured to the floor and ceiling with duct tape. In larger 

areas, a frame of steel or wooden studs can be built to hold the polyethylene sheeting. Epoxy can also be 

used to fasten the sheeting to the floor or ceiling. 

All supply and air vents, doors, and pipe chases in the containment area must be sealed with polyethylene 

sheeting to minimize the spread of mold and mold spores to other areas of the building. Stairs should also be 

sealed if a riser is missing or open. (A pipe chase is an enclosure through which pipes are run; a riser is the 

upright piece of a stair step, from tread to tread.) 

Heavy mold growth on ceiling tiles may affect HVAC systems if the space above the ceiling is used as a 

return air plenum. In such cases, containment would be installed from floor to ceiling deck. The filters in the 

air-handling units serving the affected area may have to be replaced once the remediation is complete. 
118 

CHAPTER 6

CONTAINMENT AND PERSONAL PROTECTIVE EQUIPMENT (PPE) 

Lesson 3 Full Containment

Full containment is recommended for the clean up of mold-contaminated surface areas of more than 

100 square feet and when intense or long-term exposures are expected. It is also recommended if it 

appears likely that the occupant's space would be further contaminated if full containment were not 

used because high levels of airborne dust or mold spores are likely. Full containment requires double 

layers of polyethylene sheeting to create a barrier between the moldy area and other parts of the 

building. A decontamination chamber or airlock—an area with doors between the contaminated area 

and the clean area—should be built for entry into and exit out of the remediation area. 

The entryways from the outside into the airlock and from the airlock into the containment area should 

be slits covered by flaps on the outside surface. The chamber should be large enough to hold a waste 

container and allow a worker to put on and remove Personal Protective Equipment (PPE). All 

contaminated PPE, except respirators, should be placed in a sealed bag while in this chamber. 

Respirators should be worn until remediation workers are outside the decontamination chamber. 
119 

CHAPTER 6

CONTAINMENT AND PERSONAL PROTECTIVE EQUIPMENT (PPE) 

Lesson 4 Personal Protective Equipment (PPE)

The primary function of personal protective equipment (PPE) is to limit mold exposure. 

If a remediation job disturbs mold, and mold spores then become airborne, the risk of respiratory exposure 

increases. Actions likely to stir up mold include breaking moldy porous materials such as wallboard, using 

invasive procedures to examine or remediate mold growth in wall cavities, stripping or peeling wallpaper to 

remove it, and using fans to dry items. 

Gloves

Gloves protect the skin from contact with mold. They also protect the skin from potentially irritating cleaning 

solutions. Long gloves that extend to the middle of the forearm are recommended. 

The material from which gloves are made should be suited to the type of materials being handled. If you 

choose to use a biocide, such as chlorine bleach, or a strong cleaning solution, gloves should be made from 

natural rubber, neoprene, nitrile, polyurethane, or polyvinylchloride (PVC). If a mild detergent is being used, 

ordinary household rubber gloves are suitable. The routine use of biocides is not recommended. (For more 

information on the use of biocides in mold remediation, see Lesson 7 of Chapter 1.) 

Goggles

Properly fitted goggles or full-face respirators provide eye protection. Goggles must be designed to keep out 

dust and small particles. Safety glasses or goggles that have open vent holes are not acceptable. 

Respirators

Respirators protect remediation workers from inhaling airborne mold, mold spores, and dust. Three types of 

respiratory protection are described: minimum, limited, and full. Only respirators approved by the National 

Institute for Occupational Safety and Health (NIOSH) should be worn during mold remediation. These 

respirators must be used according to any applicable Occupational Safety and Health Administration (OSHA) 

regulations. 

Use minimum PPE when cleaning up a small area affected by mold (less than 10 square feet total). 

Minimum PPE includes gloves, goggles/eye protection and an N-95 respirator. An N-95 respirator covers the 

nose and mouth, filters out 95 percent of airborne particulates, and is available in most hardware stores. It 

does not provide eye protection. 

Limited PPE includes the use of half-face or full-face air purifying respirators (APRs) equipped with P100 

filter cartridges. These respirators have inhalation and exhalation valves that filter the air and ensure it is free 

of mold particles. The P100 filters do not remove vapors or gases, and the half-face APRs do not protect the 

wearer's eyes. Limited PPE may be warranted when the total surface area affected by mold is between 10 

and 100 square feet. Professional judgment should be used to make the final determination about whether to 

wear limited PPE. 

Full PPE includes a full-face, powered air purifying respirator (PAPR). It is recommended when more than 

100 square feet of mold is found, when high levels of airborne dust or mold spores are likely, or when intense 

or long-term exposures are expected. A powered air purifying respirator uses a blower to force air through a 

P100 filter. The filtered air is supplied to a mask that covers the wearer's face or a hood that covers the entire 

head. Positive pressure within the hood prevents unfiltered air from entering through penetrations or gaps. 

Individuals must be trained to use their respirators before they begin remediation. 

Disposable clothing is recommended for medium and large remediation projects. It prevents the transfer 
120 

and spread of mold to clothing and eliminates skin contact with mold. When limited protection is warranted, 

disposable paper coveralls can be used. When full protection is required, a body suit of breathable material, 

such as TYVEK® , and mold-impervious disposable head and foot coverings should be used. All gaps, such 

as those around ankles and wrists, should be sealed. (Many remediators use duct tape to seal clothing.) 

Personal Protective Equipment (PPE)

• Minimum: Gloves, N-95 respirator, goggles/eye protection 

• Limited: Gloves, N-95 respirator or half-face respirator with HEPA 

filter, disposable overalls, goggles/eye protection 

• Full: Gloves, disposable full body clothing, head gear, foot coverings, 

full-face respirator with HEPA filter 
121 

MOLD REMEDIATION KNOWLEDGE TEST

Chapter 6 CONTAINMENT AND PERSONAL PROTECTIVE EQUIPMENT (PPE) 

Lesson 1 Overview of Containment 

QUESTION 1 

Professional judgment should be used when determining how and when to use containment. 

Please click on your answer. 

• True 

• False 
122 

MOLD REMEDIATION KNOWLEDGE TEST

Chapter 6 CONTAINMENT AND PERSONAL PROTECTIVE EQUIPMENT (PPE) 

Lesson 1 Overview of Containment 

QUESTION 1 

Professional judgment should be used when determining how and when to use containment. 

Please click on your answer. 

• True 

• False 

The correct answer is "True." 

This topic was covered in Chapter 6, Lesson 1. 
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Chapter 6 CONTAINMENT AND PERSONAL PROTECTIVE EQUIPMENT (PPE) 

Lesson 2 Limited Containment 

QUESTION 2 

When using limited containment, which of the following materials should be used to enclose a contaminated 

area? 

Please click on your answer. 

• A. Plywood 

• B. Fabric, blankets, or old sheets 

• C. 6-mil polyethylene sheeting 

• D. Newspaper 
124 

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Chapter 6 CONTAINMENT AND PERSONAL PROTECTIVE EQUIPMENT (PPE) 

Lesson 2 Limited Containment 

QUESTION 2 

When using limited containment, which of the following materials should be used to enclose a contaminated 

area? 

Please click on your answer. 

• A. Plywood 

• B. Fabric, blankets, or old sheets 

• C. 6-mil polyethylene sheeting 

• D. Newspaper 

The correct answer is C. 

This topic was covered in Chapter 6, Lesson 2. 
125 

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Chapter 6 CONTAINMENT AND PERSONAL PROTECTIVE EQUIPMENT (PPE) 

Lesson 3 Full Containment 

QUESTION 3 

When should full containment be used? 

Please click on your answer. 

• A. When more than 100 square feet of mold is found 

• B. When high levels of airborne dust or mold spores are likely 

• C. When intense or long-term exposures are expected 

• D. All of the above 
126 

MOLD REMEDIATION KNOWLEDGE TEST

Chapter 6 CONTAINMENT AND PERSONAL PROTECTIVE EQUIPMENT (PPE) 

Lesson 3 Full Containment 

QUESTION 3 

When should full containment be used? 

Please click on your answer. 

• A. When more than 100 square feet of mold is found 

• B. When high levels of airborne dust or mold spores are likely 

• C. When intense or long-term exposures are expected 

• D. All of the above 

The correct answer is D. 

This topic was covered in Chapter 6, Lesson 3. 
127 

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Chapter 6 CONTAINMENT AND PERSONAL PROTECTIVE EQUIPMENT (PPE) 

Lesson 3 Full Containment 

QUESTION 4 

A remediation worker or other individual in a full containment area must wear a respirator while in the 

remediation area and airlock. 

Please click on your answer. 

• True 

• False 
128 

MOLD REMEDIATION KNOWLEDGE TEST

Chapter 6 CONTAINMENT AND PERSONAL PROTECTIVE EQUIPMENT (PPE) 

Lesson 3 Full Containment 

QUESTION 4 

A remediation worker or other individual in a full containment area must wear a respirator while in the 

remediation area and airlock. 

Please click on your answer. 

• True 

• False 

The correct answer is "True." 

This topic was covered in Chapter 6, Lesson 3. 
129 

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Chapter 6 CONTAINMENT AND PERSONAL PROTECTIVE EQUIPMENT (PPE) 

Lesson 4 Personal Protective Equipment (PPE) 

QUESTION 5 

N-95 respirators provide eye protection. 

Please click on your answer. 

• True 

• False 
130 

MOLD REMEDIATION KNOWLEDGE TEST

Chapter 6 CONTAINMENT AND PERSONAL PROTECTIVE EQUIPMENT (PPE) 

Lesson 4 Personal Protective Equipment (PPE) 

QUESTION 5 

N-95 respirators provide eye protection. 

Please click on your answer. 

• True 

• False 

The correct answer is "False." 

This topic was covered in Chapter 6, Lesson 4. 
131 

CHAPTER 7

EVALUATING THE REMEDIATION 

Lesson 1 Completing Mold Remediation — Fix the water problem and 

clean up the mold

How do you know when you have finished remediation? Ultimately, it is a judgment call. People should be 

able to occupy or work in the building without health complaints or physical symptoms. The most important 

action, if mold growth is to be controlled in a building, is to eliminate the source of moisture that caused the 

mold problem. No matter how good the mold cleanup is, if the water problem is not solved, mold will return. 

Therefore, determining whether moisture in the building is being controlled is key in assessing the 

effectiveness of the remediation effort. If moisture is not being controlled, even removing all the mold growing 

in the building will be only a temporary solution. 

A visual inspection of the area that has been remediated should show no evidence of present or past mold 

growth. There should be no moldy or musty odors associated with the building, because these odors suggest 

that mold continues to grow. If mold or moldy odors are present in the building, the remediation has not been 

effective. 

Keep in mind that remodeling, cleaning, and construction may have introduced new building materials or 

chemicals capable of causing upper respiratory irritation that, in some individuals, may mimic the symptoms 

caused by exposure to mold. 

How Do You Know When You Have Finished Remediation/Cleanup?

1. You must have completely fixed the water or moisture problem. 

2. You should complete mold removal. Use professional judgment to 

determine if the cleanup is sufficient. Visible mold, mold-damaged 

materials, and moldy odors should not be present. 

3. If you have sampled, the kinds and concentrations of mold and mold 

spores in the building should be similar to those found outside, once 

cleanup activities have been completed. 

4. You should revisit the site(s) shortly after remediation, and it should 

show no signs of water damage or mold growth. 

5. People should be able to occupy or re-occupy the space without 

health complaints or physical symptoms. 

6. Ultimately, this is a judgment call; there is no easy answer. 
132 

CHAPTER 7

EVALUATING THE REMEDIATION 

Lesson 2 Considering Bioaerosol Sampling 

Bioaerosol sampling (air sampling for mold or other biological contaminants) usually is not necessary to 

determine remediation effectiveness. In fact, bioaerosol sampling may be less effective at determining the 

success of remediation than visual and sensory surveys of the area. 

Although sampling may be of some help in judging remediation effectiveness, remember that a negative 

sampling report must not be used in place of a visual survey. Factors such as barometric pressure, inside 

and outside temperatures, activity levels, and humidity may dramatically reduce or increase the spore levels 

within a building. Air sampling for mold provides information on what was in the air only for the moment when 

the sampling occurred. It is important, therefore, that sampling not replace visual inspection. 
133 

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Chapter 7 EVALUATING THE REMEDIATION 

Lesson 1 Completing Mold Remediation - Fix the water problem and clean up the mold 

QUESTION 1 

Which of the following steps are necessary for determining the effectiveness of a mold removal project? 

Please click on your answer. 

• A. Determine that the moisture problem has been corrected 

• B. Visually ensure that water damaged and moldy materials have been removed from the site 

• C. Check to see that individuals returning to the site are not experiencing any health complaints or physical 

symptoms 

• D. All of the above 
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MOLD REMEDIATION KNOWLEDGE TEST

Chapter 7 EVALUATING THE REMEDIATION 

Lesson 1 Completing Mold Remediation - Fix the water problem and clean up the mold 

QUESTION 1 

Which of the following steps are necessary for determining the effectiveness of a mold removal project? 

Please click on your answer. 

• A. Determine that the moisture problem has been corrected 

• B. Visually ensure that water damaged and moldy materials have been removed from the site 

• C. Check to see that individuals returning to the site are not experiencing any health complaints or physical 

symptoms 

• D. All of the above 

The correct answer is D. 

This topic was covered in Chapter 7, Lesson 1. 
135 

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Chapter 7 EVALUATING THE REMEDIATION 

Lesson 2 Considering Bioaerosol Sampling 

QUESTION 2 

Sampling must always be conducted in order to ensure that the remediation process was successful. 

Please click on your answer. 

• True 

• False 
136 

MOLD REMEDIATION KNOWLEDGE TEST

Chapter 7 EVALUATING THE REMEDIATION 

Lesson 2 Considering Bioaerosol Sampling 

QUESTION 2 

Sampling must always be conducted in order to ensure that the remediation process was successful. 

Please click on your answer. 

• True 

• False 

The correct answer is "False." 

This topic was covered in Chapter 7, Lesson 2. 
137 

CHAPTER 8

COMMUNICATING WITH THE BUILDING OCCUPANTS 

Lesson 1 Communicate When You Remediate

Communication with building occupants is essential for successful mold remediation. Some occupants will 

naturally be concerned, and their concern may increase if they believe information is being withheld. The 

status of the building investigation and remediation should be openly communicated, along with information 

on known or suspected health risks. 

Small-scale remediations will not usually require a 

formal communication process, but do be sure to take 

individual concerns seriously and consider whether 

formal communication is required. Managers of 

medium or large remediation efforts should make 

sure they understand and address the concerns of 

the building occupants and communicate clearly what 

has to be done. Depending on the situation, 

communication, communication strategies, and 

communication issues may also be handled by others 

such as building owners, school principals, and public 

relations specialists. Some organizations or buildings 

may have a communications strategy that can be 

used, or they may wish to develop a comprehensive 

strategy. 

Communication techniques may include regular memos and meetings with occupants (with time for 

questions and answers). The communication techniques used will depend on the scope of the remediation 

and the level of occupant concern. Tell the occupants about the size of the remediation project, the activities 

planned, and the schedule. Send or post regular updates on the remediation's progress. Send or post a final 

memo when the project is completed or hold a final meeting. Try and resolve issues and occupant concerns 

as they come up. When building wide communications are frequent and open, remediation managers can 

spend more time resolving the mold problem and less time responding to occupant concerns. 

Communication is especially important if occupants are relocated during remediation. When deciding 

whether to relocate occupants, consider the size of the area affected, the extent and types of health effects 

exhibited by the occupants, and the potential health risks associated with debris and activities during the 

remediation. Be sure to ask about, accommodate, and plan for individuals with asthma, allergies, 

compromised immune systems, and other health concerns. Smooth the relocation process and give 

occupants an opportunity to participate in resolving the problem by clearly explaining the disruption of the 

workplace and work schedules. Notify individuals of relocation efforts in advance, if possible. 

Special communication strategies may be warranted when treating a mold problem in a school. Teachers, 

parents, and other affected groups should be notified as soon as significant issues are identified. Consider 

holding a special meeting so parents can learn about the problem and ask questions of school authorities, 

particularly if it is necessary or advisable to vacate the school during remediation. 

In some cases, particularly when large areas are contaminated with mold or complaints run high among 

teachers or students, it may be a good idea to hire a remediation professional who can provide expert 

information to concerned parents and teachers, as well as do the remediation work. Often, giving parents 

and teachers access to a professional early in the investigation and remediation process will reduce their 

concern during the latter stages of the remediation. It is important that the best information available be 

provided to everyone who might be affected by the investigation and remediation. 

Communicate When You Remediate

• Establish that the health and safety of 

building occupants are top priorities. 

• Demonstrate that the occupants' concerns 

are understood and taken seriously. 

• Present clearly the current status of the 

investigation or remediation efforts. 

• Identify a person whom building occupants 

can contact directly to discuss questions 

and comments about the remediation 

activities 
138 

Please note: EPA does not regulate mold or mold spores in the air. EPA does not certify mold remediators or 

inspectors. 
139 

MOLD REMEDIATION KNOWLEDGE TEST

Chapter 8 COMMUNICATING WITH THE BUILDING OCCUPANTS 

Lesson 1 Communicate When You Remediate 

QUESTION 1 

It is best to keep a mold remediation project a secret from building occupants as long as possible. 

Please click on your answer. 

• True 

• False 
140 

MOLD REMEDIATION KNOWLEDGE TEST

Chapter 8 COMMUNICATING WITH THE BUILDING OCCUPANTS 

Lesson 1 Communicate When You Remediate 

QUESTION 1 

It is best to keep a mold remediation project a secret from building occupants as long as possible. 

Please click on your answer. 

• True 

• False 

The correct answer is "False." 

This topic was covered in Chapter 8, Lesson 1. 
141 

CHAPTER 9

PREVENTION 

Lesson 1 Mold Prevention

Mold Prevention

Keep the building and furnishings dry. 

When things get wet, dry them quickly (24-48 hours). 

Perform routine maintenance, cleaning, and repairs. 

The key to mold prevention is moisture control. Water entry into buildings or building crawl spaces should be 

controlled. If water enters a building through a leaking roof or because of a flood or accident, it should be 

removed immediately and affected areas should be dried out. 

Hidden Areas

Special attention should be given to areas that are hidden, but that might have gotten wet. Areas behind 

walls and in ceilings, crawl spaces, and attics are frequently overlooked and not dried carefully. In general, 

all wet areas should be completely dried within 48 hours to prevent mold from growing. 

Routine Maintenance is Important

A number of items frequently involved in mold problems should be checked and 

maintained routinely. Furnace humidifiers must be cleaned regularly to prevent mold and 

bacterial growth. Ducts in which humidifiers are installed should also be checked to 

ensure water has not leaked into the furnace or filter areas. Stand-alone humidifiers 

should be cleaned very frequently to ensure that they are not moldy. Special attention 

should be paid to any filters in the humidifier because they can become moldy and the 

humidifier can spread spores throughout the area. Carpeted areas around the humidifiers 

should also be monitored for wetness. Humidifiers should be set to produce less than 60 

percent relative humidity in the building. Relative humidity greater than 60 percent is 

likely to result in condensation in the building, which can lead to mold growth. 

HVAC systems should be checked routinely because mold in a ventilation system may be spread throughout 

the building. Drain or condensate pans should also be checked routinely because they can become 

reservoirs for mold and bacteria if not installed and maintained properly. These pans are designed to remove 

water produced by cooling hot air from the ventilation system. If the pans do not drain, or are not cleaned 

frequently, they may allow water to enter the HVAC system and contaminate the ventilation ducts in the 

building. The pans themselves may also grow mold and allow mold spores to be spread throughout the 

building. Filters for the HVAC system also should be kept dry and changed frequently. 

Toilet and bathroom areas should be carefully monitored for water and plumbing leaks. Rippling wall 

coverings, cracked drywall tape, peeling paint, and other signs of water damage should be investigated 

quickly. These signs frequently indicate that water has leaked, and hidden mold growth and damage are 

likely. Water seepage into crawl spaces or basements should also be stopped quickly to ensure that mold 

will not grow, and measures such as the installation of sump pumps or a regrading of the area around the 

building should be considered to prevent future leaks. Any areas that smell moldy or musty should also be 

investigated to ensure that water has not entered and mold is not growing. 

Buildings should be located, landscaped, built, and renovated with consideration for the climate. A building 

that is not suited to the climate can have moisture problems. Buildings inevitably will get wet, both inside and 

out, and they must be allowed to dry or mold will grow in them. Selection and location of building materials 

and furnishings can also be made with mold prevention in mind. In frequently damp or wet areas, more moldresistant materials can be used; for example, some woods are more resistant to mold than particle board or 

pressed board. 
142 

Mold Prevention Tips 

MOISTURE CONTROL IS KEY 

Keep the building clean and dry. Dry wet or damp areas within 48 hours. 

Fix leaky plumbing and leaks in the building envelope as soon as possible. 

Watch for condensation and wet spots. Fix the sources of moisture problems as soon as possible. 

Prevent moisture due to condensation by increasing surface temperature or reducing the moisture level in 

air (humidity). To increase surface temperature, insulate or increase air circulation. To reduce the 

moisture level in air, repair leaks and increase ventilation (if outside air is cold and dry), or dehumidify (if 

outdoor air is warm and humid). 

Keep heating, ventilation, and air conditioning (HVAC) drip pans clean, flowing properly, and 

unobstructed. 

Vent moisture generating appliances, such as dryers, to the outside where possible. 

Maintain low indoor humidity, below 60 percent relative humidity (RH), ideally 30 percent to 50 percent, if 

possible. 

Perform regular building and HVAC inspections and maintenance as scheduled. 

Don't let foundations stay wet. Provide drainage and slope the ground away from the foundation. 

If you are not experienced with home/building repairs you may want to consult a professional when 

making repairs, or for assistance with mold-prevention-related changes to your home/building. 

--For large buildings: Use EPA's I-BEAM software to help manage indoor air quality. Routine maintenance 

and repairs reduce the likelihood of a mold problem in the building. (See the Resource List) 

--For schools: Use the EPA IAQ (Indoor Air Quality) Tools for Schools guidance. (See the Resource List) 
143 

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Chapter 9 PREVENTION 

Lesson 1 Mold Prevention 

QUESTION 1 

What is the key to mold prevention? 

Please click on your answer. 

• A. Improving ventilation 

• B. Maintaining a warm temperature 

• C. Controlling moisture 

• D. Closing windows 
144 

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Chapter 9 PREVENTION 

Lesson 1 Mold Prevention 

QUESTION 1 

What is the key to mold prevention? 

Please click on your answer. 

• A. Improving ventilation 

• B. Maintaining a warm temperature 

• C. Controlling moisture 

• D. Closing windows 

The correct answer is C. 

This topic was covered in Chapter 9, Lesson 1. 
145 

Knowledge Tests 

At the end of each chapter, a knowledge test reviews important information from each of its lessons. Select 

an answer and the screen will tell you whether your answer is correct; it will also direct you back to the 

lesson where you can review the information. If you are unsure of an answer, click “Reveal Answer.” A 

counter keeps track of the number of questions you have answered and your score. The scores are for your 

information only. EPA does not track your test results or provide the information to any other party. 

Chapter 1

Introduction to Mold 

Chapter 2

Where and Why Mold Grows 

Chapter 3

Finding Mold and Moisture 

Chapter 4

General Remediation Issues 

Chapter 5

Large Areas and Other Special Concerns 

Chapter 6

Containment and Personal Protective Equipment (PPE) 

Chapter 7

Evaluating the Remediation 

Chapter 8

Communicating with the Building Occupants 

Chapter 9

Prevention 
146 

Resource List 

EPA Mold Homepage - links to EPA mold documents and non-EPA resources 

www.epa.gov/mold 

EPA Resources 

A Brief Guide to Mold, Moisture, and Your Home

www.epa.gov/iaq/molds/moldguide.html 

Biological Contaminants

www.epa.gov/iaq/biologic.html 

Fact Sheet: Flood Cleanup - Avoiding Indoor Air Quality Problems

www.epa.gov/iaq/pubs/flood.html 

Hurricane Response 2005

www.epa.gov/Katrina 

Hurricane Information

www.epa.gov/naturalevents/hurricanes.html 

Indoor Air Quality (IAQ) Home Page

www.epa.gov/iaq 

Indoor Air Quality Building Education and Assessment Model (I-BEAM)

www.epa.gov/iaq/largebldgs/ibeam_page.htm 

IAQ in Large Buildings/Commercial Buildings

www.epa.gov/iaq/largebldgs 

IAQ Tools for Schools

www.epa.gov/iaq/schools 

Mold Remediation in Schools and Commercial Buildings

www.epa.gov/iaq/molds/mold_remediation.html 

Regulating Antimicrobial Pesticides

www.epa.gov/oppad001 

Should You Have the Air Ducts in Your Home Cleaned?

www.epa.gov/iaq/pubs/airduct.html 

U.S. EPA IAQ Clearinghouse 

Phone: (800) 438-4318 or (703) 356-4020 (live operator during business hours) 

Fax: (703) 821-8236 

E-mail: iaqinfo@aol.com 

Free indoor air-related documents, answers to indoor air quality (IAQ) questions, listing of state IAQ contacts 

and EPA regional contacts. 
147 

Mold in the Environment 

 Mold growing outdoors on firewood. Molds come in many colors; both white and black molds 

are shown here. 

High Resolution

 Orange colored mushroom growing on forest floor amid pine needles. 

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148 

 Mold on bread. (Note growth has started on the exterior and is gradually expanding and 

growing into the interior of the bread.) 

High Resolution

 Decomposing leaves. 

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149 

 Partially decomposed beech leaves. 

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 Partially decomposed beech leaves. 

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150 

 Mushroom: Grey Ink Cap mushroom commonly found in gardens and on compost. (photo, 

Terry Brennan) 

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151 

Magnified Mold 

 Mold growing in petri dishes. (photo, Stephen Vesper, Ph.D.) 

High Resolution

 Mold growing in petri dishes. The same type of mold is growing in both photos, but note that 

molds can change appearance as they age. In this example, the mold on the right has been 

growing for several days longer than the mold on the left. (photo, Chin Yang, Ph.D.) 

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152 

 Magnified mold and mold spores. (photo, Chin Yang, Ph.D.) 

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 Magnified mold spores. (photo, John Martyny, Ph.D.) 

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153 

 Magnified mold and mold spores. (photo, John Martyny, Ph.D.) 

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 Highly magnified mold spores, lit from behind. The spores are very small (2-5 microns) and 

become airborne easily. (photo, Terry Brennan) 

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154 

 Mold spores, highly magnified. (photo, John Martyny, Ph.D.) 

High Resolution
155 

Moisture and Moisture Damage 

 Condensation. 

High Resolution

 Condensation. 

High Resolution
156 

 Icicles. 

High Resolution

 Water leaks. 

High Resolution
157 

 Water stains. 

High Resolution

 Water stains on wall and ceiling. (photo, John Martyny, Ph.D.) 

High Resolution
158 

 Acoustic ceiling tiles with water damage. (photo, Terry Brennan) 

High Resolution

 Water stains in basement. (photo, Terry Brennan) 

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159 

 Water-damaged ceiling tiles. Air conditioning ducts above the ceiling were not insulated in several 

areas resulting in condensation on the ducts that dripped onto the ceiling tiles. (photo, Terry 

Brennan) 

High Resolution

 Puddles on flat roof. 

High Resolution
160 

 Wood showing water stains caused by roof leak. 

High Resolution

 Water from roof leak has seeped into a wall causing the paint to buckle and peel. (photo, Terry 

Brennan) 

High Resolution
161 

 When built, the roof had a hole for the drainpipe; however, a drainpipe was not installed until 

years later. The white stains on the brick are mineral deposits resulting from rain pouring through 

the drain hole onto the walls. (photo, Terry Brennan) 

High Resolution

 In this case, the icicles result from warm air in the house leaking into an attic without sufficient 

insulation. (photo, Terry Brennan) 

High Resolution
162 

 Several inches of water in a basement with a broken sump pump. (photo, Terry Brennan) 

High Resolution

 Water in the ground has seeped through the concrete walls of the basement, leaving white 

mineral deposits on the walls. The water has evaporated into this basement, increasing humidity. 

Mold is growing in some areas. (photo, John Martyny, Ph.D.) 

High Resolution
163 

 Mineral deposits on the surface of a dirt crawl space caused by chronic water problems. (This is 

not mold.) (photo, John Martyny, Ph.D.) 

High Resolution

 Flooding. EPA mold guidance is not for flood water. 

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164 

Prevention 

 Moisture issue: Foundation is wet; drain gutters are too short. Fix: Drain rain water away 

from the house, generally about 5 feet away from the foundation. Gutters below grade 

(below the soil) are protected from damage, while those above grade may be more easily 

damaged. (photo, Terry Brennan) 

High Resolution
165 

 Moisture issue: Rainwater is falling and collecting near the foundation of this house. Fix: It is 

important that the water drain away from the foundation—the ground could be sloped away 

from the foundation so that the water will run off. (photo, Terry Brennan) 

High Resolution

 Moisture issue: Disconnected downspout deposits rainwater from roof onto walls and near 

foundation. 

Fix: Connect the 2 downspouts. (photo, Terry Brennan) 

High Resolution
166 

 Moisture Issue: A lawn sprinkler is located near the outside wall of a building; the sprinkler 

sprays the wall directly, and water leaks through wall into the building. Fix: Move the 

sprinkler away from the building so that water does not wet the walls or collect near the 

foundation. (photo, Terry Brennan) 

High Resolution

 Moisture Issue: Foundation was chronically wet, water and mold damage was found on 

original structure. 

Fix: Area was regraded during construction of an addition so that water drains away from 

the foundation. 

High Resolution
167 

 An example of window flashing, applied so that water drains to the outside of the window 

and not into the surrounding frame or walls. (photo, Terry Brennan) 

High Resolution
168 

 Rust is an indication that condensation occurs on this drainpipe. The pipe should be 

insulated to prevent condensation. 

High Resolution

 Moisture issue: Condensation on uninsulated air conditioning duct. 

Fix: Insulate the duct on the outside. (photo, Terry Brennan) 

High Resolution
169 

 Moisture issue: Leaking pipes. The leaking pipes under the kitchen sink were taped; the 

pipes continued to leak, and the area got moldy. Fix: The pipes should be fixed by a 

plumber or other qualified professional. (photo, Terry Brennan) 

High Resolution

 Example of a crawlspace without mold or water problems. The site is well drained. The 

crawlspace has a vapor barrier over the earth, is air-sealed, and insulated on the walls. 

(photo, Terry Brennan) 

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170 

 Two examples of dehumidifiers. For spaces that are damp, often at high humidity, but do not 

have liquid water running through them, a dehumidifier can be used to reduce humidity. 

(photo, Terry Brennan) 

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171 

 Example of a drain pan beneath a cooling coil that slopes to a drain line and is constructed 

of stainless steel. (photo, Terry Brennan) 

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172 

 Example of exhaust vent in a bathroom. (photo, Terry Brennan) 

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173 

 Example of an exhaust hood and fan over a stovetop in a kitchen. An exhaust fan over a 

range draws heat, moisture, and contaminants out of the house. Range hoods should vent 

to the outside. (photo, Terry Brennan) 

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174 

Mold in Buildings 

 Mold growing on a suitcase stored in a humid basement. 

High Resolution

 Basement apartment (3-4 feet below ground) with mold on painted gypsum board, 

baseboard, and carpet. (photo, Terry Brennan) 

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175 

 Mold on ceiling. (photo, Terry Brennan) 

High Resolution

 Mold on painted concrete in a school building. Rainwater is wicking directly through the 

concrete walls, and there is also condensation on the earth-chilled concrete (The floor is 

about 3 feet below ground level.) (photo, Terry Brennan) 

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176 

 Mold on drywall under leaky sink. (photo, John Martyny, Ph.D.) 

High Resolution

 Plumbing leak inside wall led to mold on paneling behind mirror above bathroom sink. (The 

mirror has been removed in this photo.) (photo, S. McNeel, DVM) 

High Resolution
177 

 Moisture damage and mold growth under bathtubs. (photo, Terry Brennan) 

High Resolution

 Mold on grout. (photo, Elissa Feldman) 

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178 

 Mold inside a bathroom cabinet where condensation forms. (photo, Terry Brennan) 

High Resolution

 Mold on shower curtain. (photo, Terry Brennan) 

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179 

 Mold on air seal on sliding glass door. 

High Resolution

 Extensive mold contamination of ceiling and walls. (photo, Terry Brennan) 

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180 

 Mold on basement ceiling resulting from chronic high humidity (>90% relative humidity[RH]). 

(photo, Terry Brennan) 

High Resolution

 Colorful mold growth. (photo, Terry Brennan) 

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181 

 Sections of moldy gypsum board. (photo, Terry Brennan) 

High Resolution

 Mold on first floor beneath a through-the-wall air conditioner on the second floor. (photo, 

Terry Brennan) 

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182 

 Mold on fragment of ceiling tile. 

High Resolution

 Mold surrounding air conditioning vent in ceiling due to water leak. (photo, John Martyny, 

Ph.D.) 

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183 

 Mold growing on oriented strand board used for structural wood floor in crawl space. (photo, 

John Martyny, Ph.D.) 

High Resolution

 Mold on gypsum wallboard. (photo, Terry Brennan) 

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184 

 Mold growth on fiberboard shelf (left) and on cardboard boxes (right) due to high humidity. 

Water is condensing from the basement air, which is at approximately 90% relative humidity 

(RH). (photo, Terry Brennan) 

High Resolution

 Mold inside a wall cavity. (photo, Terry Brennan) 

High Resolution
185 

 Mold on wooden paneling. (photo, Terry Brennan) 

High Resolution
186 

Finding Mold and Moisture

 Mold (and dirt) beneath refrigerator due to chronic drip-pan overflows. (photo, Terry 

Brennan) 

High Resolution

 Mold on a vacuum cleaner stored in a damp basement. (photo, Terry Brennan) 

High Resolution
187 

 Moisture meter and moldy roof sheathing. (photo, Terry Brennan) 

High Resolution

 Measuring moisture levels of a subfloor. (photo, Terry Brennan) 

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188 

 Moldy bedroom closet. Water condensed from the air onto the gypsum board. The wall is 

cool enough for condensation because there is a hole in the insulation and it is cold 

outdoors. (photo, Terry Brennan) 

High Resolution

 Moisture meter, showing high moisture content in gypsum board behind tile. (photo, Terry 

Brennan) 

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189 

 Mold growth under ceramic tiles in a bathroom. (photo, John Martyny, Ph.D.) 

High Resolution

 Mushrooms growing at the base of and behind the baseboard below a water leak in a 

bathroom. The baseboard has been removed; the puckers in the paint are due to water 

damage. (photo, John Martyny, Ph.D.) 

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190 

 Most mold is found by simply looking. Mold beneath corkboard. (photo, Terry Brennan) 

High Resolution

 Mold inside a wall. This photo shows an interior wall with the lower portion of the drywall 

removed on one side; there is mold on the backside of the drywall caused by water leak. 

(photo, John Martyny, Ph.D.) 

High Resolution
191 

 Opening a wall with a utility knife to minimize disturbance to mold in the wall cavity. 

High Resolution

 Inside of wall from above, moldy gypsum board, insulation. (photo, Terry Brennan) 

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 Looking for mold in wall cavities by removing a section of drywall. (photo, John Martyny, 

Ph.D.) 

High Resolution

 Clear plastic tape is used to collect a sample. The sample is analyzed with a microscope to 

determine whether the substance is mold or soot. (photo, Terry Brennan) 

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 Bulk samples can be examined using reflective light microscopes, such as stereo 

microscopes or this epi microscope. (photo, Terry Brennan) 

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Cleaning, Remediation 

 N-95 disposable respirator. 

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 Cleaning with Personal Protective Equipment - gloves, goggles, N-95 respirator. 

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 Limited PPE. (photo, Chin Yang, Ph.D.) 

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 Full containment on a large job. (photo, Terry Brennan) 

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 Full containment. (photo, Terry Brennan) 

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 Full containment. (photo, Terry Brennan) 

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 Drying a carpet with a commercial specialty blower with built-in heater. (photo, Terry 

Brennan) 

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 HEPA vacuum. Care is being taken to disturb the mold as little as possible while vacuuming. 

(photo, Terry Brennan) 

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 Damp wiping surfaces with water and a small amount of detergent. (photo, Terry Brennan) 

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 Bookcases and books protected during clean-up. (photo, Terry Brennan) 

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Cleaning, Remediation 

 Cleaning Mold. 

Medium Resolution High Resolution

 Mold growing over time in a petri dish. 

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 Mold growing over time in a petri dish. 

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Glossary

AIR HANDLING UNIT (AHU): Equipment that includes a blower or fan, heating and/or cooling coils, and 

related equipment such as controls, condensate drain pans, and air filters. Does not include ductwork, 

registers or grilles, or boilers and chillers. 

ALLERGEN: A substance, such as mold, that can cause an allergic reaction. 

ANTIMICROBIAL: Agent that kills microbial growth (i.e., chemical or substance that kills mold or other 

organisms). See "Biocide" and "Fungicide." 

BIOLOGICAL CONTAMINANTS: 1) Living organisms, such as viruses, bacteria, or mold (fungi), 2) the 

remains of living organisms, or 3) debris from or pieces of dead organisms. Biological contaminants can be 

small enough to be inhaled, and may cause many types of health effects including allergic reactions and 

respiratory disorders. 

BIOCIDE: A substance or chemical that kills organisms such as mold. 

BUILDING ENVELOPE: Elements of the building, including all external building materials, windows, and 

walls, that enclose the internal space. 

CEILING PLENUM: Space between a suspended ceiling and the floor above that may have mechanical and 

electrical equipment in it and that is used as part of the air distribution system. The space is usually designed 

to be under negative pressure. 

FUNGI: A separate kingdom comprising living things that are neither animals nor plants. The kingdom Fungi 

includes molds, yeasts, mushrooms, and puffballs. In this course, the terms fungi and mold are used 

interchangeably. 

FUNGICIDE: A substance or chemical that kills fungi. 

HEPA: High efficiency particulate air (filter). 

HVAC: Heating, ventilation, and air-conditioning system. 

HYPERSENSITIVITY: Great or excessive sensitivity. 

HYPERSENSITIVITY PNEUMONITIS: A group of respiratory diseases that cause inflammation of the lung 

(specifically granulomatous cells). Most forms of hypersensitivity pneumonitis are caused by the inhalation of 

organic dusts, including molds. 

MOLD: A group of organisms that belong to the kingdom Fungi. In this course, the terms fungi and mold are 

used interchangeably. 

mVOC (microbial volatile organic compound): A chemical made by mold that is a gas at room 

temperature and may have a moldy or musty odor. 

MYCOTOXIN: A toxin produced by a mold. 

NEGATIVE PRESSURE: A condition that exists when less air is supplied to a space than is exhausted from 

the space, so the air pressure within that space is less than that in surrounding areas. Under this condition, if 

an opening exists, air will flow from surrounding areas into the negatively pressurized space. 
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PLENUM: Air compartment connected to a duct or ducts. 

PRESSED WOOD PRODUCTS: A group of materials used in building and furniture construction that are 

made from wood veneers, particles, or fibers bonded together with an adhesive under heat and pressure. 

REMEDIATE: Fix. 

SPORE: The means by which molds reproduce. Spores are microscopic. They vary in shape and range from 

2 to 100 microns in size. Spores travel in several ways: passively moved by a breeze or water drop, 

mechanically disturbed (by a person or animal passing by), or actively discharged by the mold (usually under 

moist conditions or high humidity). 

TOXIGENIC: Producing toxic substances. 

See also Indoor Air Quality, Glossary of Terms: http://www.epa.gov/iaq/glossary.html