Small plastic chambers containing alpha track detectors are often used for measuring indoor concentrations of 222Rn. This paper reports an experimental assessment of sources of error in measurements made with alpha track detector-containing chambers. The results demonstrate the feasibility of a nondestructive test for the identification of alpha track detector-containing chambers that are packaged in a way that does not effectively prevent ambient 222Rn from inducing tracks prior to field exposure. Results also indicate that there is statistically significant variation among manufacturing lots and among chemical processing batches. Error from these sources can be avoided or compensated if appropriate control measures are implemented as part of a quality assurance program during any survey using alpha track detector-containing chambers.