In our previous research sensoreffect on various petrol samples (vapours) has been detected. In order to explain the sensoreffect gas chromatography of samples was done. Results showed that more than 60% of petrol (with octane number 95) content was benzene derivatives, like toluene, 1,3-dimethylbenzene and ethylbenzene. Many countries including Latvia has determined that pure benzene content in fuel has to be below 1%. Benzene is found in the vehicle exhaust as well, as other hydrocarbons, which were present in the original fuel. OSHA (Occupational Safety and Health Administration) has determined the legal airborne permissible exposure limit (PEL) for benzene at 1ppm (averaged for 8-hour work day) and 5ppm for 15-minute exposure