During an indoor air quality (IAQ) evaluation, industrial hy- gienists may measure total volatile organic compounds (TVOC) without considering which individual volatile organic com- pounds (VOCs) make up the TVOC level. TVOC measurements are a good indication of IAQ: higher TVOC levels generally in- dicate more VOCs in the air, increasing the overall level of in- door air pollution and the likelihood of poor IAQ.
But the TVOC level alone doesn’t help industrial hygienists
discover the sources of indoor air pollution. Nor does it help
determine the presence of hazardous or irritating individual
VOCs. Identifying all VOCs is a critical step in resolving IAQ issues related to elevated chemicals and odors and assessing the
risk to building occupants.
levels. The most common VOCs found in schools are shown in
Table 2. Finally, typical levels of TVOC and formaldehyde in
various building types are shown in Figures 1 and 2.
VOCs are among the most prevalent indoor air pollutants. As
many as 1,000 different VOCs can be found in the air of homes,
offices or schools at any one time. The level of VOCs is typically
two to five times higher in indoor than in outdoor air.
New buildings may have significantly greater TVOC or
individual VOC levels because of emissions from construction materials and furnishing products. Building
occupants who are exposed to VOCs can feel so uncomfortable, distracted or sick that their symptoms interfere with their work.1 Missed work days or days
with reduced activity can cost businesses billions of
dollars in lost productivity.2-4
Exposure to individual VOCs and mixtures of VOCs
can aggravate allergies and asthma and cause a wide
variety of health concerns, including skin, eye, nose
and throat irritation; coughing; headaches; and general flu-like illnesses. When continually present at elevated levels, exposure to some VOCs can lead to
more chronic concerns, including neurological, endocrine (hormonal) and reproductive effects. Some
VOCs may even cause cancer. Other VOCs may be irritants and produce unacceptable odors when present
at very low levels.
A recent data study of 3,000 air samples collected
from 2003 through 2008 from a variety of building
types revealed a wide range of VOCs with potential
health concerns (see Figure 1). The data were obtained
from independent IAQ investigations or green building commission projects conducted by Air Quality
Sciences building consultants or other independent
consultants who use the AQS laboratory for analysis.
Data from this study is presented in Figures 1 and 2.
Table 1 lists the most frequently found VOCs among
the 3,000 samples and their typical air concentration
Individual VOCs that cause serious health problems (such as
cancer) or adversely impact neurological, endocrine and reproductive systems (reproductive toxins) need to be eliminated
from the indoor environment. VOCs that are classified as odor-ants/irritants need to be minimized to reduce complaints.
Keep in mind, however, that many VOCs fall into the “other”
category, as shown in Figure 1. These VOCs may or may not be
hazardous when considered individually; health researchers have
not yet determined whether they can cause health problems. Also
unknown are the synergistic effects within the body from these
VOCs reacting together, potentially forming new compounds. For
these reasons, industrial hygienists should continue to focus
on keeping the TVOC level as low as feasible while also iden-
Table 1. Twenty of the Most Common Chemical Pollutants Found in Indoor Air
Xylene (para and/or meta)
Limonene (Dipentene; 1-Methyl-4-
Benzene, 1-ethyl-4-methyl (4-Ethyltoluene)