A cooperation was started between the Union of Physicians of Schleswig-Holstein (Bad Segeberg, Germany) and an environmental engineer in 1992. A mobile unit for environmental analysis was set up, the Environmental analysis Van (EAV) or mobile umweltambulanz. Inspection of sites and collection of air and dust/material samples for analysis of xenobiotics were performed on request. The results of this cooperation were evaluated to show which sources of indoor pollutants could be particularly relevant to human health impairment. During a 30-month period form July 1993 to December 1995, 1793 site inspections wer conducted. Xenobiotic analysis and subsequent advising was performed in 1318 cases; enhanced concentrations of one or more toxic substances (mainly biocides such a pentachlorophenol, permethrin, and/or hexachlorocyclohexane) were found in 71% of the sites analyzed. Formaldehyde, volatile organic compounds, and contamination by molds were also documented. A follow-up was done on 80 clients of the Environmental Analysis Van, which had detected elevated concentrations of permethrin because of pyrethroid-treated carpeting. The effect of removing all contaminated carpeting on health improvement in comparison with nonremoval was statistically significant (p<0.0001). Pyrethroid-treated carpeting, which was already 5, 7 and 10 years old, revealed permethrin concentrations of 115, 100, and 150 mg/kg dust. This result indicates that indoor contamination of permethrin is highly persistent and may be the cause of adverse health effects.