The US EPA and the California Air Resources Board studied the exposures of 51 residents of Los Angeles, CA to 25 volatile organic chemicals in air and drinking water in February and July of 1987. Participants carried a personal air monitor consisting of a Tenax cartridge and a small sampling pump for two consecutive 12-hour periods. Concurrently, outdoor air samples were collected in the back yards and indoor air samples were collected in the kitchen and living room. Breath samples were collected at the beginning, middle, and end of the 24-hour monitoring period using a vanmounted spirometer employing Tedlar bags followed by collection on Tenax cartridges. All analyses were by GC/MS. Air exchange measurements were made at all homes using the perfluorotracer method. For most chemicals, personal air concentrations were greater than indoor air levels, which were in turn greater than outdoor air concentrations. Breath concentrations were more stable than air exposures and were significantly correlated with previous exposure. Using the air exchange measurements, whole-house source strengths were estimated to range between approximately zero for carbon tetrachloride to 10,000-mu-g/h for para-dichlorobenzene. Ambient concentrations in February were two-three times those in July, perhaps due to strong inversions.
