This study (2007) searched for associations between exposure to volatile organic compounds (VOCs), and physician-diagnosed asthma and wheezing in the previous 12 months in US adults. Subjects wore Organic Vapor Monitors for a period of 48–72h to measure their exposure to VOCs. Studied compounds were benzene, chloroform, ethylbenzene, tetrachloroethene (TCE), toluene, trichloroethene, o-xylene, m,p-xylene, 1,4-dichlorobenzene, and methyl tertiary butyl ether (MTBE), which were categorized into two groups: “aromatic compounds” and “chlorinated hydrocarbons”.

The mean concentration of VOCs varied from a low 0.03g/m³ for trichloroethene to a high 14.33 g/m³ for toluene.

The study found, that environmental exposures to VOCs, especially aromatic compounds, were associated with adverse respiratory effects:

• The odds of physician-diagnosed asthma were significantly higher for subjects who had been exposed to aromatic compounds with a 1.6 times increase
• The odds for wheezing attacks were significantly higher for non-asthmatic subjects who were exposed to aromatic compounds and chlorinated hydrocarbons with a 1.5 times increase

Asthma was associated the most with exposure to toluene, with a 21% increased odds for those who were exposed to it. In addition, exposures to benzene, ethylbenzene, o-xylene, and m,p-xylene were significantly associated with asthma and also wheezing. Exposure to chloroform was significantly associated with wheezing. 

Previous studies have found that high exposures to several of these compounds may lead to asthma. This study concludes, that even everyday low continuous exposures to these compounds may also have adverse health effects.