Science, Cleaning & Built Environments

Dr. Michael A. Berry


At the urging, of the editor, of [the Journal of Cleaning Restoration and Inspection], this paper has been developed and excerpted from an as yet unpublished book I have been working on since my retirement as a professor at the University of North Carolina at Chapel Hill.
It reflects what I have learned both as an environmental scientist and management professional about cleaning as a process and as a business.

The State of Cleaning today

One of the first public health statements I made when I was organizing the U. S. Environmental Protection Agency’s (EPA’s) Indoor Air Research Program in 1984 was, “There is no organized body of factual information that constitutes a science of cleaning.” 

That statement is, by and large, valid today. After observing and studying the cleaning operations, housekeeping, carpet cleaning, custodial and disaster restoration services, as they relate to meaningful environmental protection especially in our most sensitive and familiar environments, as a public health professional and educator I am concerned and disappointed in what I find.

First, there is no widely recognized definition of “clean” and “cleaning.” 

“Clean” is far too often thought to be “subjective.” A “pleasing appearance” alone, which is fundamentally an artifact of light reflectance, often remains the dominant hallmark of the clean condition.

In many residences, institutions, offices, and business environments, where people spend the vast majority of their time, speed, convenience, and low cost are priorities rather than effective cleaning.The typical performance measure of cleaning systems is time, money saved, and not the environmental quality provided. For the most part, cleaning is measured in terms of low bid, money expended and labor required. As a consequence, pollution tends to build up in a large number of indoor environments.

The economic value and benefits of a healthful built environment are not recognized and understood by the public. Rarely is it specifically understood that a clean and healthful environment is a unique form of capital for wealth creation. Effective cleaning is not widely recognized as a form of insurance or that ineffective cleaning has a high cost in the long term.

There is no hierarchy of risk management or risk reduction benefit associated with cleaning. “Cleaning for health” is an overly broad marketing slogan used throughout the industry and marketplace to sell products and service. However, there is little indication that many otherwise educated people in our modern society know or recognize in what ways effective cleaning relates to, affects, or protects human health.

High-performance, science-based, quality-building-management programs are extremely rare throughout the building services industry.Cleaning performance in the built habitat is not measured, especially in terms of environmental quality.
Without measurement, cleaning cannot be managed.

There is limited testing or efficacy with regard to cleaning technologies or processes, particularly concerning cleaning effectiveness. There is no standardized protocol by which to measure cleaning effectiveness or validate claims with regard to cleaning technologies. Many claims made with regard to the effectiveness of cleaning technologies and processes are baseless and in many cases deliberately misleading.

No wonder we have so many health complaints related to buildings.

Until these many issues and conditions are addressed and resolved, we cannot create a factual body of knowledge or a well-defined science related to built environments, and we cannot effectively manage and fully protect the health and well-being of the public.

It is my hope and intent that this paper will contribute to a better understanding and appreciation of “cleaning.”

Clean and Cleaning Defined 

To understand cleaning, its value, and effectiveness we need to define terms.

What is “clean” and what is “cleaning?” “Clean” is an environmental condition free of unwanted matter.

“Matter” is anything of substance.Substances are of three forms: solids, liquids, and gases. Substances can be living or nonliving.

Substances can be measured and described quantitatively. They are of all sizes, ranging from those visible to the eye to those seen only through an electron microscope.Some are colorless. All substances are of a certain density and influenced by gravity.

“Pollution” is unwanted matter that gets in the way of human endeavors, poses a risk, or causes an undesirable or adverse effect. Pollution goes by many names, including wastes, soils, dirt, dusts, trash, and pathogenic microorganisms. Pollution is the ever present, ubiquitous, unwanted byproduct of natural systems and human activity. Pollution constantly builds up and interferes with every human endeavor if not effectively managed.

“Cleaning” is the management process used to achieve the clean condition. Cleaning is a fundamental environmental management process of putting unwanted matter in its proper place. Cleaning includes personal hygiene, housekeeping, maintenance and restoration.

Effective cleaning is the process of extracting and removing unwanted matter to the greatest or optimum extent to reduce exposures to the unwanted matter and thereby eliminate or reduce the probability of adverse effects for humans,Valuable materials, and the natural environment.

There are many benefits of effective cleaning. First and foremost, cleaning creates a healthful condition by reducing exposures and risks. It enables sanitation, breaks the transmission chain of infectious agents, and prevents illness. Cleaning provides living and working space. In addition to human health protection, cleaning protects valuable materials and equipment, and maintains the value of property.Cleaning is a form of insurance that prevents crisis and reduces the full range of costs related to property and real estate. Cleaning manages wastes and contributes to environmental protection and sustainability.

Cleaning is one of five basic environmental management strategies.It is most effective when it is done in conjunction with the other four strategies: source management and modification, activity management, design, and dilution or ventilation.

In the built and indoor environment where humans reside the vast majority of time, all five environmental management strategies must work together to keep pollutants — gases, particles, and biopollutants — at sanitary levels. Different environments require different cleaning processes. However, assuming that source management, activity management, design intervention, and dilution or ventilation are all optimized to control unwanted matter, cleaning is always necessary for the protection of health.

Levels of Cleanliness 

There are degrees or levels of cleanliness.In the public health tradition, cleaning is viewed on three levels: sterilization, disinfection and sanitation.

For an environment to be considered sterile, it must be 100 percent free of contamination. The state of sterilization can be achieved, but it is extremely difficult and expensive to achieve. In routine cleaning, we do not as a rule attempt to sterilize things and places.

For an environment to be considered disinfected, we remove or make safe the vast majority (95 percent) of harmful substances in it. We eliminate the risks or pathogens that are most threatening to humans. A disinfected condition can be achieved, but only with a considerable amount of energy.

By definition, an unsanitary condition poses a likely health risk. The purpose of cleaning is to reduce or correct the risky condition. For an environment to be considered sanitary, we clean to the point that the environmental condition is at an acceptable risk level.

At a minimum, cleaning must always achieve a sanitary condition.If the health risk has not been improved to a level we accept as sanitary, effective cleaning has not been accomplished.

Environments must be cleaned on a regular schedule to keep them sanitary.

Cleaning Process 

Cleaning science is the body of knowledge that explains how cleaning works to be effective. Cleaning is a systematic science-based management process. Through this systematic process, cleaning manages pollution — matter whose nature, location, or quantity produces undesired or adverse effects. Cleaning reduces adverse exposure levels and risks by removing unwanted problem substances thereby reducing or eliminating exposures and adverse health effects.

The cleaning process as it is applied to an environment is comprised of the following science-based steps:

• Understanding the nature and characteristics of the environment in order for it to be made free of unwanted matter.

• Locating, identifying and understanding the physical, chemical or biological characteristics of the unwanted matter to be removed.

• Separating the matter in order that it can be removed from the environment.

• Containing and removing or transporting the unwanted matter from the environment.

• Properly disposing or repositioning the matter so as to not degrade or cause harm to other environments or the natural environmental system.

The Cleaning Arts

The skillful application of the cleaning process constitutes the various methods of effective cleaning.These methods can be thought of as the cleaning arts — art being the skillful application of science.

Cleaning activities can be viewed on four levels: personal hygiene, housekeeping, routine maintenance and restoration. Each has a different degree of knowledge. Some require special processes, equipment, and skill levels. At a minimum, each must always achieve a sanitary state; that is, each activity is done in a way that public health is protected at an acceptable risk level.

“Hygiene” is commonly understood as preventing disease and infection through cleaning. Civilized humans have always practiced hygiene so as to protect health, prevent disease and enhance social well-being. The Book of Leviticus, currently read by billions of members of three major religions of the world and written about 3,000 years ago, reads like a modern public health manual.

Good hygiene includes the absence of visible soil or malodors and harmful levels of bacteria and other microorganisms and harmful matter. Good hygiene as indicated by a state of cleanliness creates a sense of well being and among other benefits enhances health, aesthetics , comfort, social interactions and human productivity. In many instances, the process of highperformance cleaning directly aids in disease prevention and isolation.

Good hygiene — as manifested by cleanliness — maintains a healthy condition and avoids sickness and disease. In the midst of an epidemic, good personal hygiene and effective cleaning processes reduce contagiousness.

“Housekeeping” is the routine daily and weekly activity of keeping things — including pollution concentrations — in their proper place and at acceptable levels. Housekeeping relies heavily on human organizational skills and labor. Housekeeping includes a daily routine and weekly activity to maintain a building. It includes such common tasks as putting things away, collecting and emptying trash, vacuuming rugs and carpet, dusting furniture and surfaces, washing eating utensils, and mopping floors.

“Maintenance,” like housekeeping, must be performed regularly.Maintenance, however, relies on mechanical and chemical interventions like floor mats, air filters, cleaning machines, strong detergents, solvents, disinfectants and waxes to make the cleaning process work.Interim maintenance or cleaning activities are performed periodically and less often, such as scrubbing and spray buffing hard-surface floors and using extraction cleaning on carpets.This work may be done by trained housekeeping staff or by specialized cleaning technicians. Maintenance is also necessary to enable housekeeping to effectively keep the environment in a sanitary state.

“Restoration” is the activity of deep cleaning. It is the process we use to bring the environment back to order. It is required when the environment has gotten so far out of control that extraordinary actions are necessary to restore it to a sanitary condition. Restorative maintenance should be performed immediately following a disaster such as a flood or fire, or routinely as needed.It includes stripping and polishing hard-surface floors, extraction of unwanted matter from carpets, and even the replacement of building parts or furnishings after floods, fires, or other accidents. Restoration also includes facilities maintenance.

and includes the repair of electrical, plumbing, HVAC and structural problems. Specially trained technicians perform restoration.


Individuals and businesses involved in the processes of cleaning are vitally important to the management of built environments.The purpose of this paper is to help these professionals better understand environmental management principles, and armed with this information, develop and utilize high-performance cleaning systems for built environments that are scientifically measurable and assessed.


Benson, Abram, (Ed.). (1990). Control of Communicable Diseases in Humans.Washington, DC: American Public Health Association.

Berner, Maureen. (1993). Building Conditions, Parental Involvement, and Student Achievement in the District of Columbia Public School System. Urban Education 28.1: 6-29.

Berry, M. A. (1993). Protecting the built environment: Cleaning for health. Chapel Hill,N. C.: Tricomm 21st Press.

Berry, M. A. (2002). The contribution of restoration and effective operation and maintenance programs on indoor environmental quality and educational performance in schools. Proceedings: Indoor Air 2002.Monterey, CA.

Block, S. S. (1983). Disinfection, sterilization, and preservation, 3rd ed. Philadelphia: Lea and Febiger.

Cohen, S., et al. (1986). Behavior, health, and environmental stress. New York: Plenum.

Mood, Eric. (1986). Recommended Minimum Housing Standards. Washington DC: American Public Health Association.

NEA. (1995). The Healthy School Handbook. Washington DC: National Education Association. Pfeiffer, Guy, Casimir Nikel, Richard Mackarness. (1980). The Household Environment and Chronic Illness—Guidelines for Constructing and Maintaining a Less Polluted Residence. Springfield, Illinois: Charles C Thomas.

Pope, Andrew M., Roy Patterson, Harriett Burge, (Eds.). Indoor Allergens – Assessing and Controlling Adverse Health Effects.National Academy Press.

Rutala, W.A. (1987). Disinfection, sterilization and waste disposal. In: Wenzel, R.P., Prevention and control of nosocomial infections.
Baltimore: Williams and Wilkins.

Tierno, P. M. (2001). The secret life of germs.
New York: Pocket Books.

U. S. EPA. (1994). Indoor Environment Characterization of a Non-Problem Building: Assessment of Cleaning Effectiveness.Research Triangle Park, NC: Environmental Criteria and Assessment Office, U. S. Environmental Protection Agency.


Reprinted with permission of Michael A. Berry and Cleaning Science Publishing, LLC from the [month/season 201-] issue of The Journal of Cleaning, Restoration & Inspection


Science, Cleaning & Built Environments:  Created on May 15th, 2017.  Last Modified on May 15th, 2017


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About Dr. Michael A. Berry

Michael A. Berry, PhD serves on the Science Advisory Council of the Cleaning Industry Research Institute (CIRI).


Dr. Michael A. Berry retired from the US Environmental Protection Agency in 1998 after a 28 year career with that agency. In EPA he was a senior manager and scientist. He was the Deputy Director of National Center for Environmental Assessment at Research Triangle Park, NC for 22 years. During his EPA career, he had extensive interactions with private industry, trade associations, environmental organizations, governments, the federal courts, US Congress, universities world-wide, and institutions such as the National Academy of Sciences, the World Health Organization, and the North Atlantic Treaty Organization. Dr Berry is recognized internationally as an expert in the subject of indoor environmental quality. Between 1985 and 1994, he directed EPA's indoor air research program.

Since his retirement from EPA he has been a Research Professor at the University of North Carolina at Chapel Hill where he taught several course and wrote numerous articles related to business and environment, built environments, and environmental science and management. He serves as a consultant to businesses and public institutions in the evaluation of environmental management strategies and policy. He directs research on the performance of products and services related to indoor environmental quality. Currently his research focus is the area of cleaning science and indoor environmental management programs for schools and universities.

Dr. Berry served as an Army Officer in Viet Nam 1967-68. He earned a Doctor of Philosophy in Public Health from the University of North Carolina at Chapel Hill, and a Master of Science in Management from Duke University's Fuqua School of Business. He holds both Bachelor and Master of Science degrees in Mathematics from Gonzaga University.

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