Indoor Air Quality Issues

David L. Hansen, David Hansen

• Publisher: CRC Press
• Year: 2018
• Print ISBN: 9781560328667
• eBook ISBN: 9781351438919
• Topic: Biological Sciences
• Subtopic: Environmental Management
• Index: Biological Sciences

This  text examines problems such as microbial contamination, building design, ventilation systems and psychological effects. It uses a multi-disciplined approach in examining the causes and effects of the interactions between occupants and non-industrial environments. The text also provides the reader with a tool for diagnosing IAQ problems and effectively reducing them.

Chapter 1
HISTORY AND EVOLUTION

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OVERVIEW

The indoor environment is currently considered to be one of the most important health concerns for industrialized nations. How did this concern evolve? This chapter gives a brief overview of some of the major changes in the indoor environment and how those changes have impacted on occupants’ comfort and health, concentrating on Europe and, most recently, the United States.

The chapter begins with a brief look at attempts to control the indoor temperature and at early theories about the impact of the indoor environment on occupants. The rest of the chapter reviews the significant changes in the indoor environment that began after World War II with a dramatic increase in the use of synthetic materials and chemicals that produced potentially harmful indoor contaminants. Next, the “energy crisis” of the early 1970s dramatically altered building design and ventilation to produce tight structures. The combination of synthetic materials and changes in building design are the major causes of poor indoor air quality today.

This chapter also looks at another crucial factor—peoples′ perception of the indoor environment. Recent enormous media attention to potential health hazards like asbestos has promoted widespread fears that the indoor environment can cause cancer and other health problems.

LEARNING OUTCOMES

•A knowledge of the evolution of the indoor environment

•A greater understanding of the recent changes in the indoor environment

•An appreciation of the increased complexity of the indoor environment

EARLY DWELLINGS

Temperature and Comfort

The driving force throughout the evolution of the indoor environment has been comfort. Temperature is the parameter most closely associated with comfort, and a comfortable temperature has been the primary goal ever since people built permanent structures. Until relatively recently, most efforts concentrated on heating rather than cooling.

A comfortable temperature, generally considered about 72 degrees F, is essential for the perception of an acceptable indoor environment (Berglund 1989). Air that is significantly above a comfortable temperature will be perceived as stale and stuffy even if the air is actually fresh.

Hippocrates, in “Airs, Waters, and Places,” states that climate has great effects on the physique, intelligence, and temper of people (Bedford 1964). Although Hippocrates was probably referring to the outdoor environment, the indoor “climate” controls comfort, which certainly impacts on an occupant’s temperament and performance, if not intelligence and physique.

The Warming of Buildings

The earliest method of heating structures consisted of open fires, usually in the center of a room, with an opening such as a hole in the roof serving as a flue. The distribution of heat was uneven and considerable smoke was produced.

Wood, peat, and dung were among the earliest fuels used. Although coal was being used on a very limited basis by the end of the twelfth century, wood and charcoal were still the fuels of choice even in the seventeenth century (Bedford 1964).

Although emission studies were not done in centuries past, recent studies show that when emissions from indoor combustion (both smoke and gases) are not vented directly to the outdoors, significant levels of contaminants build up (Gammage 1984). How concentrated these contaminants are depends on many factors, including type of fuel and ventilation characteristics, but they can cause problems ranging from annoyance (eye irritation, for example) to severe pulmonary problems. Health problems from improperly vented combustion emissions still occur regularly in developing countries (Smith 1996).

One of the earliest techniques of warming a building without the problems associated with combustion products (smoke) was the Grecian hypocaust. In this system, hot gases from a fire accumulate in a sealed space under the floor and the whole floor essentially becomes a radiator.

The hypocaust was the first central heating system and it was no small accomplishment, because smoke and gases did not pour into the heated rooms. However, only the wealthy had this system; others made do with the more traditional “bonfire” with a hole in the roof to vent the smoke.

During the Roman Empire the hypocaust was refined to include hollow wall tiles; such systems were able to heat whole buildings without the problems associated with smoke and other by-products of combustion (Bedford 1964). With the fall of the Roman Empire, however, the hypocaust virtually disappeared.

The introduction of fireplaces, with chimneys allowing smoke to escape, provided a major improvement over open hearths. Chimneys were being used in Italy by the fourteenth century and in England by the fifteenth century (Bedford 1964). Again,chimneys were only for the wealthy, and as late as the seventeenth century the poor did not have chimneys in their homes.

The design of fireplaces kept improving to produce a more even room temperature and to remove smoke, which was still considered an annoyance rather than a health hazard. As coal became more popular, efforts to curtail smoky chimneys included the of the open coal grate.

A breakthrough occurred in the early 1700s when Gauger designed a fireplace in which outside air could be heated and passed into the room (Bedford 1964). Gauger claimed that his fireplace was a “perfect specific against the annoyance of smoke in rooms, which smutched everything in the apartments, and particularly the lace, linen, skin and eyes of the ladies” (Bedford 1964).

Central Heating

Improvements in fireplace design provided more comfort for smaller residential spaces, but fireplaces were not adequate for heating larger spaces. Larger spaces began to be heated by enclosed systems such as stoves.

In the late 1700s, hot-air furnaces, a technique that is still common, were introduced. In 1791, Hoyle obtained a patent for a steam-heating system, which rapidly became very popular. By the early 1900s, steam or hot water systems were being used to warm larger buildings. This type of system, called “central heating,” creates steam or hot water at a central source and circulates it, via pipes and/or radiators, to heat a structure.

The next advance in heating was a large-scale extension of central heating called “district heating,” in which steam plants heat groups of buildings instead of just one structure. Such systems are now common. In large cities, a single supplier may heat a majority of the larger buildings.

These systems eliminated the need for fireplaces as well as the indoor pollution associated with them. However, early steam plants used coal—usually soft coal with high sulfur content—as a source of energy. They were a significant source of pollution, which in turn could be brought into a building by mechanical or natural ventilation.

Air Conditioning

One of the first successful efforts to cool the air was developed in the mid 1800s by a physician, Dr. John Gorrie. Initially, Gorrie tried blowing air over ice in an attempt to give his patients relief from the hot Florida climate. He then developed a mechanical refrigeration system using a compressor, which is still an essential component of air conditioners (Proctor 1982). Although the first commercial air conditioner was produced by Willis Carrier in 1914, cooling systems did not become common for many decades. Today, their widespread use permits year-round control of interior temperatures.

Ventilation

Initially, only natural ventilation was available; this relied on open windows and structure “leaks” created by doors and other building components. During the early eighteenth century, ventilation by mechanical means was introduced when Desagliers invented a hand-operated centrifugal fan that could bring fresh air into a building or extract air. This method was used in 1736 for ventilating the House of Commons (Bedford 1964).

The invention of electric fans permitted mechanical ventilation to became an important method for introducing and directing outside air throughout buildings. Mechanical ventilation is especially important in large buildings that are subdivided into small offices, since natural ventilation (such as opened windows) is not adequate in such situations.

Today, the introduction of conditioned fresh air into a building is controlled by complex heating, ventilating, and air conditioning (HVAC) systems. How HVAC systems impact on the indoor environment is discussed in the chapters on building design and microbial contamination.

THEORIES ABOUT AIRBORNE CONTAMINATION

In the past, there was little information about the relationship between smoke and health, and smoke was regarded merely as an annoyance. Most people, especially those without the resources to have a fireplace with a good flue, certainly were more concerned with warmth than with annoyances.

Moreover, the first concerns about the emissions from fires focused on the outdoor environment, not the indoor. In London, for example, as far back as the seventeenth century, outdoor air pollution was a major environmental concern. In 1661, John Evely wrote a treatise to King Charles II entitled “Fumigium, or the Inconvenience of the Aer and Smoak of London Dissipated.” Evely observes, “The air is here eclipsed with such a cloud of sulphure, as the sun itself is hardly able to penetrate and the weary traveller at many miles distance sooner smells than sees the city to which he repairs” (Singh 1995).

In 1733, John Arbuthnot, physician to Queen Anne, published a book on the effects of air on human bodies. He too noted the impact of fuel emissions, writing, “The air of Cities is not so friendly to the lungs as that of the Country, for it is replete with Sulphorous Streams of Fuel” (Arbuthnot, 1733).

Those early scientists who looked at the indoor environment had various theories, some about comfort, others about health. For example, it was generally accepted that because crowded rooms were excessively warm, the discomfort experienced was attributable solely to the temperature. Gauger, whose fireplace improvements are discussed earlier in this chapter, disagreed. He believed that it was not the warmth of a room that caused problems, but its inequality of temperature and lack of ventilation (Gauger 1714).

In the late eighteenth century, Lavoisier studied the composition of air in occupied indoor environments, and his work “did not hesitate to attribute to carbonic acid themalaise generally attributed to warmth alone” (Leblanc 1842). For more than 100 years, people subscribed to Lavoisier’s theory that an excess of carbon dioxide from in overcrowded rooms caused the discomfort

Approximately 150 years ago, D. B. Reid recognized the importance of a good indoor environment. He wrote, “Mental anxiety may, perhaps, be considered the most powerful enemy to the duration of human life, and, next to it, defective nutriment, whether in quantity or quality. But after these, no other cause, at least in modem times, appears to have inflicted so great an amount of evil upon the human race as defective ventilation” (Reid 1848).

Reid, like Gauger before him, believed that ventilation was an essential component of the quality of an indoor environment. He was concerned with the amount of fresh air supplied to the indoor environment and also the chemical and physical properties of the air. Reid was remarkably perceptive about the influence of the indoor environment on our well-being.

In the mid 1850s, a major shift in Lavoisier’s carbon dioxide theory was proposed by Pettenkofer, a professor of hygiene in Munich who lectured on health-related issues (Sundell 1994). Pettenkofer proposed that “the unpleasant symptoms were not due merely to warmth or humidity, or to carbon dioxide excess or oxygen deficiency, but rather to the presence of very small quantities of organic material from the skin and lungs” (Pettenkofer 1862). Pettenkofer felt that the concentration of carbon dioxide was an indicator of airborne contamination that could cause problems but not the culprit (Bedford 1964). Pettenkofer and a number of other authors of his time suggested 1000 ppm of carbon dioxide as a limit value for an adequately ventilated room (Sundell 1994). These theorists were right about the role of carbon dioxide as an indicator, and carbon dioxide concentrations are currently measured when monitoring ventilation. This is discussed in more detail in the chapter on building design.

During the late nineteenth century, researchers studying contaminants in indoor air looked for evidence of toxicity from expired breath. This concept, called the “anthro-potoxin theory,” could not be proved, and lack of ventilation continued to be associated with discomfort and not health (Bedford 1964). Although later researchers were able to show that occupants of poorly ventilated rooms experienced discomfort and loss of appetite, they were not able to show the cause of discomfort (Winslow 1915).

In the early part of this century, research by Hill demonstrated the importance of air movement as a comfort factor. In Hill’s experiments, eight students were placed in a small (3 cubic meters) airtight chamber with provision for heating and cooling, and with electric fans for creating air movement. Hill found the students’ thermal discomfort was relieved to an astonishing extent by putting on the fans, even if...

Table of contents

• Cover
• Half Title
• Title Page
• Copyright Page
• Table of Contents
• Introduction
• Chapter 1. History and Evolution
• Chapter 2. Building-Associated Illnesses
• Chapter 3. Building Design and Air Quality
• Chapter 4. Volatile Organic Compounds
• Chapter 5. Microbial Contamination
• Chapter 6. Impact of Psychosocial and Other Factors
• Chapter 7. Diagnosing IAQ Problems
• Chapter 8. Pro-Active Ways of Preventing IAQ Problems
• Appendix A. Indoor Air Quality Questionnaire-Building Operations
• Appendix B. Monthly Inspection
• Index