The Air We Breathe – Indoor Air Quality Testing for Home Inspectors

 

“All I need is the air that I breathe” was a popular lyric from a song by The Hollies in 1974. We expect that each breath we take will be esthetically pleasing and healthy. Since the majority of our time is spent indoors, we are essentially “trapped” with the quality of the indoor air that is characteristic of our surroundings. Indoor air quality (IAQ) encompasses everything that contributes to the level of occupant comfort. As Figure 1 illustrates, besides the usual temperature and humidity concerns in an indoor setting, occupants must be concerned about particulates, molds and mycotoxins, carbon monoxide and carbon dioxide, allergens, radon and volatile organic compounds (VOCs). Home inspectors must consider many facets of air quality when performing an inspection. 

Rules and regulations exist for outdoor air quality. For instance, the United States has made significant improvements to combat pollution, beginning with the Clean Air Act of 1970, which led to the use of catalytic converters in automobiles and resulted in a significant reduction of carbon monoxide. The Kyoto Protocol of 1995 began to address manmade emissions of carbon dioxide and the possible global-warming implications of increasing CO2 levels. The Montreal Protocol in 1987 addressed the manufacture and use of chlorofluorocarbons that impacted stratospheric ozone levels. 

Conversely, IAQ is largely unregulated, but some guidelines do exist. The U.S. Green Building Council was founded in 1993 to promote the construction or renovation of homes and businesses with the goal of energy-efficient and healthy buildings.1 New buildings are constructed with the intent of being LEED-certified, a goal that usually is achieved before the building is occupied (Note: LEED stands for Leadership in Energy and Environmental Design.) However, once any building is occupied, indoor air becomes mixed with “contaminants,” which can include particulate matter, molds and mycotoxins, allergens and VOCs (Figure 1). In the United Kingdom and other countries, similar guidelines (such as BREEAM) exist.2 The main focus of this article will be on the volatile aspects of IAQ (that is, radon, carbon monoxide [CO], carbon dioxide [CO2] and VOCs). 

Radon 
Radon is a silent killer. Radon is unique in the list of IAQ issues because this radioactive gas is not present in indoor air because of activities or products introduced by the occupant, but instead it can be present as a consequence of the area of the country in which the structure is located or the type of bedrock or soil on which a structure is built. Radon is the leading cause of lung cancer among nonsmokers and it causes about 21,000 deaths per year.3 Radon gas is generated from the natural breakdown of uranium in soil, rock and water. The average indoor level is 1.3 picoCuries per liter (pCi/L). A level of 4.0 pCi/L is considered the “action level” for remediation. Testing usually requires several days because of the low levels of radioactive events resulting from radon gas decay. Devices can range from simple single-use kits to continuous radon monitors. Radon testing often is requested by homebuyers before they finalize real estate transactions. 

Figure 1

Carbon Monoxide and Carbon Dioxide 
Carbon monoxide (CO) and carbon dioxide (CO2) can be monitored as part of IAQ testing. Most homes have CO alarms, but many of these alarms will sound only after the monitor reaches a level of 30 ppm. However, symptoms that indicate CO poisoning can start appearing when CO levels fall between 2 and 30 ppm. Therefore, monitoring CO can help to activate early remediation efforts in the event of a CO leak. Carbon dioxide is generated by the respiration of occupants. CO2 levels can be easily monitored using inexpensive detectors. Many inspectors consider CO2 levels to give a reasonable estimation of IAQ and comfort levels. The American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) provides ventilation guidelines4 for indoor air quality stating that indoor levels should not exceed 1,030 ppm. Ventilation should be reconsidered in areas where these levels are exceeded. 

VOCs 
The U.S. Environmental Protection Agency (EPA) defines a volatile organic compound (VOC) as any compound that participates in atmospheric photochemical reactions.5 Although photochemical reactivity is important in outdoor air, indoor air typically uses the definition of VOCs as any chemical that easily vaporizes at room temperature. VOCs encompass many chemical categories such as hydrocarbons, aromatics and aldehydes, just to name a few. VOCs are emitted from common household products and from surfaces that have been chemically treated (for example, painted, varnished or laminated, among other treatments). 

The term VOC can be very misleading for consumers because of the prevalence of the terms “no VOC” and “low VOC,” which are used to refer to products that limit the use of VOCs referred to in the EPA definition. However, these no-VOC and low-VOC products still contain other volatile materials such as glycols and glycol ethers, meaning that using these products will still have a negative impact on IAQ. 

According to the EPA, the level of VOCs indoors is typically two to five times higher than the amount of VOCs in outdoor air.5 If you could take a “snapshot in time” of the VOCs present in a room, the amounts would vary depending on occupant behavior. For instance, VOC levels can dramatically increase when a person uses personal care products (deodorants and perfumes) or household products (paint, caulk and PVC cement). The amounts present can be even higher in the winter months because people keep rooms warmer in the winter. Volatility increases and decreases with corresponding temperature changes. 

With people spending more time indoors, the necessity for understanding IAQ becomes important. The U.S. Green Building Council recommends that VOC levels be less than 500 nanograms per liter (ng/L).1 These units are equivalent to micrograms per cubic meter (μg/m3), which are the units typically reported for LEED testing. Molhave6 suggested that the recommended comfort range for total VOC (TVOC) is <200 ng/L, and that values of 200 to 3,000 ng/L are generally acceptable unless levels of individual VOCs are very high. He suggested people experience discomfort when VOC levels are between 3,000 and 25,000 ng/L, and that the TVOC level is toxic at >25,000 ng/L. In general, these VOC levels are still at an order of magnitude that is lower than most OSHA levels associated with individual exposure to chemicals in the workplace. However, one must be cognizant of the fact that people spend most of their time indoors during the workday or at home during nonbusiness hours, and that they want their indoor air to be both esthetically pleasing and healthy. 

Why VOC Analysis?
Many home inspectors incorporate a VOC analysis into their everyday service offerings. For others, this is not the case. For these inspectors, the question is, “In what types of situations would it be beneficial for the client to have an understanding of the level of VOCs present?” The most common opportunities for VOC testing come from clients who are undergoing a major life event. For instance, having a new baby is a good time for consumers to understand the level of VOCs in their home, especially in the infant’s bedroom. Infants, young children and senior citizens are the most susceptible to the effects of elevated levels of VOCs. Likewise, a person who is facing new health challenges may want to request a VOC IAQ test. 

Clients are also interested in VOC levels when they purchase a new home so they can have an idea of the indoor environment they are moving into. Many homes are remodeled just before the sale, so lingering VOCs from materials of construction can be a concern. New furniture purchases, carpet installation and other additions to the home also can lead to major IAQ changes and lingering VOC problems. 

VOC Testing 
VOC testing can be achieved using several sampling devices. Bag sampling, canister sampling and thermal desorption tubes equipped with a pump are the most common choices. Bag sampling is achieved either using an evacuated bag or a positive displacement pump to push air into the bag for a whole air sample. The VOC range is typically on the order of C1-C12 and the bags are typically single use. Canister sampling involves using an evacuated steel vessel to collect whole air samples. Sampling times can vary from a few minutes to 24 hours, depending on the valve setting. The canisters have a VOC range of C1-C12, and they can be conditioned and reused. Finally, the thermal desorption tube (TDT) (Figure 2) is a glass or stainless steel tube filled with sorbent material(s). Compounds are captured by the sorbents as air passes through the TDT; typically, air is drawn through the tube using a low-flow collection pump (100-200 mL/min). Multiple sorbents may be used to achieve the collection of a range of chemical classes. These tubes can have a VOC range of C3-C20, depending on the desorption temperature used. Figure 3 illustrates the differences between the sampling media. 

Figure 2

Figure 3

Figures 4 and 5 illustrate the various sources of VOCs observed in indoor air samples. These VOCs can be categorized according to the type or classification of VOCs present. As you can see, VOCs can originate from many different sources. Most notably, the VOCs can be associated with building materials (Figure 4) and occupant lifestyle choices (Figure 5). The average TVOC in a home setting is approximately 1,900 ng/L; this average is based on TVOCs in approximately 8,000 homes that were tested. VOC levels are usually the highest after remodeling projects or construction processes, and they also are elevated when occupants use alcohol-based products and personal care products. 

Figure 4

Mold VOCs (MVOCs) 
Other VOCs that can be detected from indoor air samples are mold VOCs (MVOCs). MVOCs are produced by the digestive processes of mold and are an indication of active mold growth. Mold VOCs include furans and alcohols. A mold spore test may reveal the presence of spores, but the air sample may prove negative for the presence of MVOCs if the mold isn’t actively growing in dry conditions, where mold spores could be temporarily dormant. Conversely, you can observe MVOCs, which can indicate the initiation of mold growth, without seeing any visible presence of mold spores. 

Figure 5

Formaldehyde 
Formaldehyde is the simplest VOC that is present in indoor air samples. Elevated levels of formaldehyde can lead to throat irritation and respiratory distress, and it can exacerbate asthmatic conditions. You can sample the level of formaldehyde by using passive badges or active air samples. 

Passive badge sampling involves collecting airborne formaldehyde by diffusion, either through a static air layer or by permeation through a membrane into a collection media. Typically, a badge filled with sorbent material is placed or worn in an environment for a recommended period of time (24-48 hours). The primary advantage of passive sampling is the ease and low cost of collection. However, when performing passive sampling, it is important to understand that environmental factors can impact the sampling. Stagnant air, with minimal air movement, will significantly reduce the effective sample volume and potentially generate a sample result that does not accurately represent the level. 

The primary advantage of active sampling is the collection of a known large sample volume. A large sample volume also provides the ability to detect lower levels of formaldehyde. 

All wood products naturally emit formaldehyde. The presence of wood products in a home, such as wood flooring and cabinetry, can lead to elevated levels of formaldehyde. Higher emissions can be observed from pressed woods such as plywood and oriented strand board (OSB). Formaldehyde is also present in older insulations that were manufactured from phenol-formaldehyde resins. 

There is much confusion regarding testing wood flooring for formaldehyde emissions. This typically requires a laboratory that can perform chamber testing according to guidelines established by the California Air Resources Board (CARB).7 Room testing of formaldehyde leads to test results that take into account all sources of formaldehyde in the room. 

Conclusions 
By including VOC testing as part of a comprehensive IAQ test, home inspectors can provide information to clients about unseen chemicals that may be present due to construction, remodeling or occupant choices. This information can be useful to clients who want to understand IAQ’s impact on their family’s health, identify problem odors that may exist or gain useful information for completing real estate transactions. 

References 
1. U.S. Green Building Council. Washington, DC. http://www.usgbc.org/. 

2. BREEAM. Watford, United Kingdom. http:// www.breeam.com/. 

3. U.S. Environmental Protection Agency. Health Risk of Radon. https://www.epa.gov/radon/ health-risk-radon. 

4. ANSI/ASHRAE Addendum n to ANSI/ ASHRAE Standard 62-2001. Ventilation for Acceptable Indoor Air Quality. Atlanta, GA: American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc.; 2003. https://www.ashrae.org/file%20library/doclib/ public/200418145036_347.pdf. 

5. U.S. Environmental Protection Agency. Indoor Air Quality (IAQ). Volatile Organic Compounds’ Impact on Indoor Air Quality. https://www.epa. gov/indoor-air-quality-iaq/volatile-organic-compounds-impact-indoor-air-quality. 

6. Molhave L. Volatile Organic Compounds, Indoor Air Quality and Health. Indoor Air. 1991;1(4): 357-376. 

7. CA.gov. California Environmental Protection Agency, California Air Resources Board. Formaldehyde. http://www.arb.ca.gov/research/indoor/ formaldehyde.htm.