Synergist - August 2010

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.

Study Results

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

Rank

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

Specialized Testing

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

Chemical Toluene (Methylbenzene) Xylene (para and/or meta) Ethanol Undecane Xylene, ortho Benzene, ethyl Benzene, 1,2,4-trimethyl Limonene (Dipentene; 1-Methyl-4- (1-methylethyl)cyclohexene) Hexanal Heptane Cyclopentasiloxane, decamethyl Nonane Benzene, 1-ethyl-4-methyl (4-Ethyltoluene) Acetone Dodecane Benzene Hexane 2-Propanol (Isopropanol) Decane Cyclohexane, methyl