Testing methods for Carbon Monoxide: The only reliable method currently used to test for the presence of carbon monoxide is an electronic device known as a carbon monoxide alarm. In the home, CO detectors should be placed in areas where the family spends most of its time such as the family room, bedroom, or kitchen, but placed far enough away from obvious and predictable sources of CO, such as a gas stove, to avoid false alarms.

Some of the attributes of urea-formaldehyde (UF) resin include high tensile strength, flexural modulus, and heat distortion temperature, low water absorption, mold shrinkage, high surface hardness, and volume resistance. UF copolymeric resins are present in many building materials such as wood adhesives which are used in the manufacture of pressed wood products including particle board, medium-density fiber board (MDF), plywood, finish coatings (acid-cured), textile treatments, as well as in the production of UF foam insulation (UFFI). However, most people are unaware that formaldehyde is given off by materials other than UFFI. Certain types of pressed wood products (composition board—e.g., MDF, paneling, etc.), carpeting, and other material can be formaldehyde sources. Many of these products use a UF-based resin as an adhesive. Some of these materials will continue to give off formaldehyde much longer than UFFI. Like the majority of VOCs, formaldehyde levels will decrease substantially with time and/or with increased ventilation.

Health Risks: For some people, formaldehyde can be a respiratory irritant, and continuous exposure to it can be dangerous. More specifically, chronic, low-level, continuous, and even intermittent exposure to formaldehyde can cause chemical hypersensitivity and provides an accelerating factor in the development of chronic bronchitis and pulmonary emphysema. This has caused considerable concerns about the risks of cancer and bronchial health impacts from formaldehyde. These concerns and several market factors are driving major changes in the composition and technology of these resins. In addition, significant pressure from the green building movement through market selection and certification programs, plus emissions regulations from the California Air Resources Board, has moved manufacturers to seek new ways to reduce formaldehyde emissions or eliminate formaldehyde entirely from formulas. It should be noted that upon condensing, HCHO forms a liquid with a high vapor pressure. Due to its high reactivity, it rapidly polymerizes with itself to form paraformaldehyde. Because of this reaction, liquid HCHO needs to be kept at a low temperature or mixed with a stabilizer (such as methanol) to prevent or minimize polymerization.

Many of the symptoms associated with exposure to aliphatic hydrocarbons may include watery eyes, nausea vomiting, dizziness, weakness, central nervous system effects such as depression, convulsions and, in extreme cases, coma. Other symptoms may include pulmonary and gastrointestinal irritation, pulmonary edema, bronchial pneumonia, anorexia, anemia, nervousness, pain in the limbs, and numbness. Benzene is found in most hydrocarbons and is considered to be one of the more serious contaminants and is known to cause leukemia. Air quality tests may be necessary as well as tests for contaminants in the soil around the foundation.

Pesticides are carefully regulated by the Federal Government, in cooperation with the States, to ensure that they do not pose unreasonable risks to human health or the environment. There are currently more than 1055 active ingredients registered as pesticides, which are formulated into thousands of different pesticide products that are available in the marketplace including some of the most widely used over the past 60 years that are persistent and have become globally distributed.

According to the EPA, “The process of registering a pesticide is a scientific, legal, and administrative procedure through which we examine the ingredients of the pesticide; the particular site or crop where it is to be used; the amount, frequency, and timing of its use; and storage and disposal practices. In evaluating a pesticide registration application, we assess a wide variety of potential human health and environmental effects associated with use of the product. The company that wants to produce the pesticide must provide data from studies that comply with our testing guidelines.”

The EPA also states that “Potential human risks range from short-term toxicity to long-term effects such as cancer and reproductive system disorders.” These include aldrin, chlordane, dichlorodiphenyltrichloroethane, dieldrin, endrin, heptachlor, mirex, toxaphene, and lindane (hexachlorocyclohexane, HCH). Many pesticides (most notably chlordane, used for termite treatment) are serious hazards. It is hoped that ecological methods of pest control will in the future replace the overdependence on chemicals that now threatens our ecosystem. The EPA regulates “pesticides under broad authority granted in two major statutes, the Federal Insecticide, Fungicide, and Rodenticide Act and the Federal Food, Drug, and Cosmetic Act. These laws have been amended by the Food Quality Protection Act and the Pesticide Registration Improvement Act.”

Different mold species will vary enormously in their tolerance to temperature and humidity extremes. The key to controlling indoor mold growth is to control moisture content, and the temperatures of all surfaces, including interstitial surfaces within walls. Mold generally needs a temperature range between 40°F and 100°F to grow, and maintaining RH levels between 30% and 60% will help control mold and many of these known biological contaminants. Winter humidification and summer dehumidification controls/modules can supplement central HVAC systems when climate excesses require additional conditioning measures.

Exposure to fungus in indoor air settings has emerged as a significant health problem of great concern in both residential environments as well as in workplace settings. Fungi are primitive plants that lack chlorophyll and therefore feed on organic matter that they digest externally and absorb or must live as parasites. True fungi include yeast, mold, mildew, rust, smut, and mushrooms. When mold spores land on a damp spot indoors, they can grow and start digesting whatever they are growing on.

Four vital elements are needed for mold to grow, they are: viable spores, a nutrient source (organic matter like wood products, carpet, and drywall), moisture, and warmth. The mere presence of humid air in itself is not necessarily conducive to fostering mold growth, except where air has an RH level at or above 80% and is in contact with a surface. Mold spores are carried by air currents and can reach all surfaces and cavities of buildings. When the surfaces and/or cavities are warm and contain the right nutrients and amounts of moisture, the mold spores will grow into colonies and gradually destroy the things they grow on. Likewise by removing any of the four essential growth elements, the growth process is inhibited or nonexistent.

To execute a mold remediation project, the first step requires determining the root cause of the mold growth. The next step is to evaluate the order of magnitude of the mold growth, which is usually done through visual examination. Since old mold growth may not always be visible, investigators may need to use instruments such as moisture meters, thermal imaging equipment, or borescope cameras to identify moisture in building materials or “hidden” mold growth within wall cavities, HVAC ducts, etc. Toxic molds and fungi are a significant source of airborne VOCs that create IAQ problems as can be seen in Fig. 7.4. Toxicity can arise from inhalation or skin contact with toxigenic molds. Some molds produce toxic liquid or gaseous compounds, known as mycotoxins, in addition to infectious airborne mold spores which often cause serious health problems to residents and workers.

While bacteria cause bacterial infections, viruses cause viral infections. And while antibiotic drugs usually kill bacteria, they are not effective against viruses. Examples of infections caused by bacteria include strep throat, tuberculosis, and urinary tract infections. Common diseases caused by viruses include chicken pox, AIDS, and common colds. In some cases, it may be difficult to determine whether a bacterium or a virus is causing a person’s symptoms. Many ailments such as pneumonia, meningitis, and diarrhea can be caused by either type of microbe.

Bacteria and viruses are minute in size and readily become airborne and remain suspended in air for hours which makes them a cause of considerable concern due to their ability to transmit infectious diseases. While there are many methods for the infection to spread, the most significant, from an epidemiological point of view is airborne transport. Microorganisms can become airborne when droplets are given off during speech, coughing, sneezing, vomiting, or atomization of feces during sewage removal. Q fever (also known as query fever), which is a bacterial infection caused by the bacteria Coxiella burnetii, is another emerging infectious disease among US soldiers serving in Iraq.

Liquid and solid airborne particles (aerosols) in indoor air originate from many indoor and outdoor sources. These particles may differ in size, shape, chemical composition, and biological composition. Particle size signifies the most important characteristic affecting particle fate during transport and it is also significant in affecting their biological properties. Bacterial aerosols have also been found to be a means to transmit a number of major diseases as shown in Table 7.3 below:

According to Professor Lidia Morawska of Queensland University of Technology in Australia, the degree of hazard created by biological contaminants including viruses in indoor environments is controlled by a number of factors like:

The physical characteristics of the indoor environment as well as the design and operation of building ventilation systems are of paramount importance. Ducts, coils, and recesses of building ventilation systems often provide fertile breeding grounds for viruses and bacteria that have been proven to cause a wide range of ailments from influenza to tuberculosis. Likewise, a number of viral diseases may be transmitted in aerosols derived from infected individuals. A number of infectious viral diseases and associated causal viruses transmitted through air are shown below in Table 7.4.

Mites: Mites are microscope bugs that thrive on the constant supply of shed human skin cells (commonly called dander) that accumulate on carpeting, drapes, furniture coverings, and bedding (Fig. 7.7). The proteins in that combination of feces and skin shedding are what cause allergic reactions in humans. Dust mites are perhaps the most common cause of perennial allergic rhinitis. Dust mites are the source of one of the most powerful biological allergens and flourish in damp, warm environments. It is estimated that up to 15% of people are allergic to dust mites which due to their very small size (250–300 μm in length) and translucent bodies, are not visible to the naked eye. To be able to give an accurate identification, one needs at least a 10× magnification. Dust mites have eight hairy legs, no eyes or antennae, and a mouthpart group in front of the body (resembles head) and a tough, translucent shell. Dust mites have multiple developmental stages, commencing with an egg, then developing into larva, followed by several nymph stages, and finally the adult. They also prefer warm, moist surroundings like the inside of a mattress particularly when someone is lying on it, but they may also accumulate in draperies, carpet, and other areas where dust collects. The favorite food of mites appears to be dander (both human and animal skin flakes). Humans generally shed about 1/5 ounce of dander (dead skin) a week. Dust mite populations are usually highest in humid regions and lowest in areas of high altitude and/or dry climates.

Ants: Ants are found throughout the United States, although species found in different regions of the country vary. There are in excess of 20 varieties of ants invading homes and offices throughout the United States, particularly during the warm months of the year (Fig. 7.8). Worldwide, there are more than 12,000 species, but of these, only a limited number actually cause problems. Among the more common ant species in the United States are the Argentine, Odorous House, Carpenter, Fire, Pavement, and Pharaoh Ants. Destructive ant species include fire and carpenter ants. Fire ants are vicious, unrelenting predators and have a powerful, painful sting. More than 32 deaths in the United States have been attributed to severe allergic reactions to fire ant stings. Ant infestations are more likely to occur in single-family dwellings, because colonies usually nest outdoors and will only come inside in search of food or water.

Termites: Although there are more than 2000 species of termites across the world, only 50 or so of those species are found within the United States. Termites live in colonies; this means they live and work together to gather food and raise their young (larvae). Termites can pose a major threat to structures, which is why it is important to address any termite infestation as soon as possible. A qualified termite control company, or inspector should look for the many telltale signs termites usually provide such as small holes in wood, straw-shaped mud tubes, crumbling drywall, termite insect wings, and sagging doors or floors (Fig. 7.9).

The Occupational Safety and Health Administration (OSHA) has a noise exposure standard which is set at just below the noise threshold where hearing loss may occur from long-term exposure. The impact of noise on physical stress reactions can be readily observed when people are exposed to noise levels of 85 dB or higher. The safe maximum level is set at 90 dB averaged over 8 h. If the noise is above 90 dB, the safe exposure dose becomes correspondingly shorter. Adverse stress-type reaction to excessive noise can be broken down into two stages. The first stage is where noise is above 65 dB making it difficult to have a normal conversation without raising one’s voice. The second is the link between noise and socioeconomic conditions that may further lead to undesirable stress-related behavior, increase workplace accident rates or in many cases, stimulate aggression and other antisocial behaviors when they are exposed to chronically excessive noise.