After sniffing of glue solvents (mixture of aliphatic hydrocarbons: boiling fraction 60-90 degrees C, ethylacetate and toluene) a blood alcohol concentration of 1.96 permille was indicated with an instrument using the infrared wavelength of 3.4 micrometer for the spectrophotometrical determination of breath alcohol. Testing of the individual solvents with a simple manual procedure showed linear relationships between concentrations in breathing air and the false positive breath alcohol values. Aliphatic hydrocarbons predominantly are responsible for the false positive breath alcohol determination. With 500 micrograms/liter a value of nearly 1.5 permille can be produced (using the factor of 2100 for the calculation of the blood alcohol concentration from breath alcohol). With ethylacetate or toluene up to 1 milligram/liter 0.5 permille ethanol in the blood will erroneously be found. The problem of recognition of crossreactive other gases by the measurement at two wavelengths (3.4 and 9.2 micrometer) is discussed.