November 25, 2004

Indoor Air Quality: Part I-What It Is

Fourteen-year-old Bill A. arrives in the school nurse's office complaining of watery eyes, persistent cough, and a burning sensation in his throat, nose, and eyes. He reports having been sent to your office by his science teacher. You inquire about his recent activities and discover that the class has been performing dissections of preserved animal organs. What follow-up would you perform and what would you do for Bill?

Do these symptoms strike you as vague and perhaps questionable in authenticity? This is often the manner environmental irritants or toxicants present in a child if exposure is short and limited. For chronic, low level exposure, these same complaints may persist or intensify. Symptoms will often disappear once the exposure is eliminated, which may either confuse the health care professional or present an etiological clue. While you may encounter a client with no environmental component to his or her symptoms, how many have you unknowingly missed? Do you feel competent to assess for potential exposure to pollutants and identify sources?

Presented in two parts, Indoor Air Quality (IAQ) will be addressed as an environmental health issue. Given the vast number of common pollutants found in indoor air, it would be difficult to explore all of these in this column. This month's focus, Indoor Air Quality-Part I: "Indoor Air: What It Is," will begin with a history and definition of IAQ, case studies, and examination of two known pollutants: combustion pollutants and volatile organic compounds or VOC's. Indoor Air Quality-Part II, "What It Does," will define frequently used terms; review research based health outcomes from known toxicants; describe symptomatology of short and long term exposures, intervention, and prevention; and offer practitioner resources.

Case Studies

Case 1. Bill A., a 14-year-old high school student, participated in science lab dissecting animal eyes. The class wore gloves and protective goggles while working. It was observed that the students were not performing this lesson under a ventilation hood, rather at lab stations with some classroom windows open. Bill felt symptomatic during most of class and was sent to the nurse's office.

Case 2. Eight-year-old Sarah P. was seen in the school nurse's office over a period of months suffering from chronic headaches, stuffiness, dizziness, and falls. Her frequent visits prompted the nurse to contact the child's mother, Mrs. P. Further investigation and discussions with Mrs. P. revealed the other three family members living in the household were experiencing cold and allergy symptoms, headaches, dizziness, sinus pain and fatigue. Onset was in late September. (Sattler, Afzal, Condon, Belka, & McKee, 2001).


1. What is your definition of indoor air?

2. Can you identify at least two sources of indoor air pollution?

3. Why are children at greater risk?

4. Can you identify resources to assist you in identifying an indoor air problem?

IAQ-A Definition and Brief History

Indoor air is that which we breathe in our 'built' environment, e.g., homes, hospitals, businesses. In the case of children, this might be their home, daycare center, school, sports arena, or recreational building. There is widespread agreement that children today spend up to 90% of their time indoors, therefore making this exposure a substantial one (Children's Environmental Health Network [CEHN], 1999; American Academy of Pediatrics [AAP], 2003).

To better understand why and how IAQ has become a health concern, it is useful to know a bit of history as it pertains to the broader issue of air quality. An abbreviated recounting of federal legislation that affects air quality and pollution, as taken from the Environmental Protection Agency's (EPA) web site, is found in Table 1. Although only the radon legislation directly addresses indoor air, other legislation provide the historical framework of awareness of air pollution in general. Key to remember is that many of the outdoor air contaminants are found in our indoor environment.

Air quality has been an acknowledged concern for the last 30 years. IAQ awareness seems to have begun after the energy crisis of 1970's. Since that time, we have been constructing buildings more tightly to conserve heat and air conditioning. Fresh air penetration is minimized to control costs. In many cases, indoor humidity increases greatly as a result. Synthetic materials, which emit gases, are commonplace now in construction of buildings and furnishings. Carpeting has been used extensively in homes and schools and acts as a reservoir for pollutants and emits gases. Wood burning stoves, which became a mainstay in certain parts of the country to reduce heating costs, increases indoor combustion pollutants as well as particulates. With structures becoming tighter and more energy efficient, IAQ has declined so significantly that the EPA's Science Advisory Board has ranked indoor air pollution as one of the top five risks to public health in the united States (Wigle, 2003).

Table 1. Air Quality History

Currently, there are no federal standards for IAQ in homes or schools, although monitoring and measuring methods exist (EPA, 2003). The 2003 EPA Draft Report on the Environment highlights the difficulty of assessing IAQ, largely owing to the overwhelming number of buildings, homes, and schools in the U.S., the lack of research, and the difficulty that would exist to generalize from such studies. To date, only two pollutants have been studied sufficiently to produce credible data: radon and environmental tobacco smoke (ETS). With an acknowledged problem of indoor air pollution, how are children put at risk?

What Makes Children unique? ;r

The field of pediatrics clearly identifies children as different from adults in a vast range of areas. The AAP (2003) identifies six stages from fetus to adolescent or 18 years. Children consume more oxygen (due to higher metabolic rates), and more food and water per pound of body weight than an adult (AAP, 2003). Rapid growth and development, potential for high levels of exposures due to their environment and immature detoxification systems are universal to all children (National Academy of Sciences, 1993).

From conception to adulthood, children move through windows of vulnerability unique to each stage of development. Tragedies resulting from fetal exposures during critical periods have been known for years: maternal consumption of alcohol, thalidomide, diethylstilbestrol, and mercury. Little research has been conducted regarding vulnerable childhood periods, which leaves practitioners with less certainty about when critical periods may occur. A growing body of evidence proves the consequences to children's health from lead, mercury, environmental tobacco smoke (ETS), and pesticides. These hazards and more may be part of many children's daily indoor air environment. Recognizing the large number of hours spent indoors, children are put at risk from poor IAQ. What these contaminants are and where they come from is essential knowledge to reduce exposure and risk.

What It Is: Two Known Indoor Air Contaminants

Although no "master list" exists of indoor air pollutants, a comprehensive list can be compiled from multiple, reliable sources. Wigle (2003) presents three broad categories of indoor contaminants: (a) gases and vapors, (b) particulate matter-large and small, (c) dust (p. 271). These categories provide a useful way to organize the vast array of pollutants. Combustion products and VOC's fall under the category of gases and vapors and are presented below. [/Voie: Environmental tobacco smoke (ETS) is considered a combustion product; however, due to the extensive information about its effects, the topic will be treated in future column.] This is an introduction to these pollutants, sources, and general health effects.

Combustion pollutants. The Consumer Product Safety Commission (CPSC) in it's collaborative publication "What You Should Know About Combustion Appliances and Indoor Air Pollution" states combustion pollutants are gases or particles that come from burning materials (page 2). These are commonly caused by appliances of the modern day life, e.g., furnaces, dryers, wood stoves. The clinician may often notice symptoms will be seasonal.

VOC's. These chemical compounds vaporize at room temperature into gases from multiple liquid or solid sources. The individual chemical compounds may differ in level present in any one location; however, the combination of multiple VOC's is of serious concern. These gases emanate from a vast number of items in the home and school and are suspected of causing "sick building syndrome." A few of the common sources are pesticides, solvents, cleaning materials, air fresheners, bleach, household cleaners, spray product propellants such as furniture wax or hair spray, and nail polish and remover. These products contain an array of chemicals such as benzene, chloroform, vinylidene chloride, and formaldehyde, many of which are known carcinogens. VOC's will likely be higher in new construction and indoor air. According to CEHN, 1999 (p. 138), "a strong association between living in a mobile home more than 10 years and developing squamos cell carcinoma of the nasopharynx" has been shown. Because an adequate description of each chemical would be prohibitive for this column, this introduct\ion to VOC's will be limited to formaldehyde, as it is present in so many products of every day life and thus may be applicable to nurses' client population.

Practice Points

Once again, learning how to "ask the right questions" may assist you in determining health problems and potential linkage to indoor air problems. If indoor air is suspected as a problem ask about time of onset of symptoms, location at time of onset (e.g., home, school, daycare), or any recent changes in built environment locations. (Note: A comprehensive list of questions will be included in the Indoor Air Quality Part II-What It Does.) If the school has a health and safety committee, the school nurse can become a member. Participation by school nurses can be extremely important as often the school nurse is the only knowledgeable health professional in this setting. Refer to the resource list to begin expanding your knowledge of indoor air.

What is Next?

This introduction to indoor air provides examples of only two pollutants. Suggestions for further reading will address more in- depth explanations and direct you to credible resources for patients and families. Indoor Air Quality Part II-What it Does will address illnesses linked to IAQ, prevention and intervention measures, how to include key questions in a history, how to conduct a home inventory, and additional resources, until then, consider an inventory of your own home or workplace and perhaps identify some of the sources described. Becoming aware of our own surroundings is a first step in identifying how children are exposed.

Case Study Postscript

Case 1. Bill A. incurred a low level exposure to formalin in an inadequately ventilated science lab. Symptoms persisted several hours, upon investigation with the school, all dissections were ceased until the completion of a new lab and installation of fans to provide better ventilation. Names of laboratory suppliers who do not use formalin as a preservative were found. Educating teachers and staff as to their health risks, Occupational Health and Safety Administration (OSHA) standards, and how to protect their students was incorporated into the nurse's intervention.

Case 2. The school nurse urged the family to have their home checked for elevated CO levels. A gas and electric employee verified levels were very high and repairs were made to the heating system. The nurse's recognition of the symptoms was critical to the resolution of this family's health problems.

Hot Box: Indoor Air Pollutants

Combustion Pollutants

Identified Pollutants: CO, NO^sub 2^, sulfur dioxide (SO^sub 2^), particles. These are products of the following fuel sources: natural gas or liquid propane, fuel oil, kerosene, wood, and coal.

CO: Colorless, tasteless, odorless gas

NO^sub 2^: Orange-reddish gas with pungent odor

SO^sub 2^: Colorless, watersoluble gas

Particle Matter: May be called particulate matter (PM), a broad term for mixtures of solids and liquids in droplet form. Indoor combustion pollutants contain particulates smaller than 2.5um, called fine particles (PM^sub 2.5^). These can remain suspended for longer periods of time and can travel easily (CEHN, 1999).

Common Sources: Appliances (vented and un-vented) such as ranges, ovens, furnaces; gas hot water heaters or clothes dryers; space heaters; wood or coal burning stoves; fireplaces; charcoal being burned indoors; ice re-surfacing equipment (Schneider & Freeman, 2000) and indoor recreational activities such as truck and tractor events (CEHN, 1999); outdoor air; exhaust from cars, lawn mowers, or any machinery with internal combustion engines; hobbies such as wood burning, welding, or soldering (CPCS, 2004); school laboratories, vocational arts areas.

Routes of Exposure: Inhalation

Clinical Effects: Mucous membranes of the eyes, nose, throat, respiratory tract, and, in the case of CO, the CNS and cardiovascular system. Amount and length of time exposed may have an effect on symptoms.

CO: Symptoms will vary greatly and appear to have a poor correlation with level of exposure. The range of symptoms include fatigue, headache, cognitive impairment, flu-like symptoms (i.e., dizziness, weakness, nausea, vomiting), skin pallor, palpitations, confusion, coma or death, potential of delayed neuropsychological sequelae up to 240 days post exposure (AAP, 2003; CEHN, 1999).

NO^sub 2^: Low level exposure-irritation of respiratory tract, particularly the lower portion; increased risk of respiratory infections in young children; asthmatics exposed to low levels while exercising show narrowing of airways. High level exposure- irritation of the respiratory tract, decreased pulmonary function, shortness of breath, and death (CEHN, 1999; AAP, 2003; CPSC, 2004).

SO^sub 2^: Highly water soluble and irritating to eyes and upper respiratory tract. Low level exposure-irritation of eye, nose, and respiratory tract. High levels-decreased lung function with a narrowing of airways, resulting in wheezing and difficulty breathing; asthmatics are particularly affected (CEHN, 1999;AAP, 2003; CPSC, 2004).

Particle Matter: Increase in respiratory symptoms; overall health effects will depend upon size of particle and chemical make-up; small particles are easily inhaled and will deposit deeper into the lung (Schneider & Freeman, 2000).


Identified Pollutant: Formaldehyde. Nearly colorless, water- soluble gas with a distinct pungent odor, classified by the EPA as a probable human carcinogen.

Common Sources: Plywood, paneling, fiberboard, particleboard, sub- flooring, furniture, cabinets; permanent press fabrics, draperies, carpets, and flooring as a water repellent; mobile homes; urea- formaldehyde insulation (used in home construction until the early 1980's); tobacco smoke; gas heaters and ovens, paints, temporary classrooms, science labs (AAP, 2003; Schneider & Freeman, 2000).

Route of Exposure: Inhalation and dermal

Clinical Effects: Route and amount impact symptoms. Airborne formaldehyde acts as an upper respiratory tract irritant causing burning or tingling in the throat and nose as well as eyes (may occur in school setting with exposure to formalin). Symptoms resolve with removal of the irritant and are temporary. Asthmatic infants and children may be more likely to react to exposure (AAP, 2003; CPSC, 2004). Even low level exposure, such as that experienced in science labs, may result in sensitization and subsequent allergic response to future exposures (D. Alexander, personal communication, April 16, 2001).

Gases and Vapors: Carbon monoxide (CO), nitrogen dioxide (NO^sub 2^), formaldehyde, radon, volatile organic compounds (VOC's), and pesticides

Paniculate Matter: Toxicants-ETS, paniculate matter from other combustion processes, asbestos. Biologiesanimal dander, fugal spores, bacteria, viruses, pollens, arthropod antigens

Dust: Pesticides, heavy metals (Wigle, 2003, p. 270)


American Academy of Pediatrics, Committee on Environmental Health. (2003). Pediatrie environmental health (2nd ed.). Elk Grove, IL: American Academy of Pediatrics.

Children's Environmental Health Network. (1999). Training manual on pediatrie environmental health: Putting it into practice. Retrieved May 14, 2003 from

Consumer Product Safety Commission. (2004). What you should know about combustion appliances and indoor air pollution Retrieved March, 2004 from cpscpub/pubs/452.html

Environmental Protection Agency. (2003). Technical document: EPA's draft report on the environment 2003. Retrieved February, 2004 from tdAir13.pdf

National Academy of Sciences. (1993). Pesticides in the diets of infants and children. Washington, DC: National Academy Press.

Sattler, B., Afzal, B., Condon, M., Belka, E., & McKee, T. (2001). Safe workplaces and healthy learning places: Environmentally health schools. Washington, D.C.: American Nurses Association Continuing Education Module.

Schneider, D., & Freeman, N. (2000). Children's environmental health reducing risk in a dangerous world. Washington, DC: American Public Health Association.

Wigle, D. T. (2003). Child health and the environment. New York: Oxford University Press.

Ann Pike-Paris, BS, MS is a consultant, East Aurora, NY.

The Environmental Health hot Topics column focuses on issues, information, and practical guidelines related to environmental health problems, including sources of toxicants and resources for nurses to prevent, minimize, or treat adverse environmental exposures particularly as they relate to children. To suggest topics, obtain author guidelines, or to submit queries or manuscripts, contact Ann Pike-Paris, MS, RN, section Editor; Pediatrie Nursing, East Holly Avenue Box 56; Pitman, NJ 08071-0056; (856) 2562300 or FAX (856) 256-2345.

Copyright Anthony J. Jannetti, Inc. Sep/Oct 2004