Exposure to certain common indoor air pollutants may impair older adults’ lung function, a small study suggests.

Researchers say the findings raise concerns that the chemicals, known as volatile organic compounds (VOCs), might exacerbate lung or heart disease symptoms in older adults.

VOCs are chemicals emitted from a range of products, including paints, varnishes, household cleaning agents, glue, inks and building materials. Because concentrations of the chemicals are up to five times higher indoors than outdoors, VOCs are generally considered indoor air pollutants.

But while studies have linked on-the-job exposure to VOCs to respiratory effects, it has been unclear what effects lower, everyday exposures might have in the general population — particularly among elderly people, who could be particularly susceptible to any adverse effects on lung function.

For the new study, published in the European Respiratory Journal, South Korean researchers tested lung function in 161 adults older than 60 who were living at home but spent their days at one of three elder-care centers.

Each participant underwent spirometry up to eight times, on separate days. Spirometry is a test that measures the amount of air that moves in and out of the lungs with each breath, as well as the speed at which it flows.

The researchers also took urine samples to test for byproducts of four different VOCs, and for substances that serve as markers of the body’s level of oxidative stress — a state that can damage cells and contribute to disease.

Overall, the researchers found that higher levels of metabolites from two VOCs — toluene and xylene — were related to poorer lung function.

When levels of the metabolites were at the 90th percentile versus the 10th percentile, participants’ FEV1 — the volume of air a person can forcibly exhale in one second — was about 1 percent lower.

"we believe this amount of reduction could exacerbate existing lung disease, such as chronic obstructive pulmonary disease, or give additional burden to existing heart disease," Dr. Yun-Chul Hong, one of the researchers on the study, told Reuters Health in an email.

This could be particularly true for elderly adults, whose lung function is already on the decline due to age, according to Hong, of the Seoul National University College of Medicine.

Because study participants had no history of on-the-job exposure to VOCs, the findings suggest that even everyday environmental levels of the air pollutants can harm lung function, Hong said. He added, however, that further studies should be done to confirm the results.

Moreover, the findings point to an association between VOC metabolite levels and lung function — but do not prove that the chemicals directly impair lung function.

However, the researchers did find evidence of a potential mechanism by which VOCs could affect lung health. Higher levels of VOC metabolites were related to higher levels of oxidative-stress markers, and increases in those markers, in turn, were related to poorer lung function.

Those findings, Hong’s team writes, support the theory that VOCs might affect lung health by exacerbating oxidative stress.

SOURCE: European Respiratory Journal, online March 29, 2010.

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