Benzene is a widely used chemical in industry, but it is known to be toxic and a carcinogen. In addition to regulating industrial occupational exposure, 2 benzene content in gasoline and its emission from traffic are concerns for public health. In addition to time spent in a car or in traffic, personal exposure is affected by sources such as tobacco smoke and residential garages. The current permissible occupation exposure limit is around 1 ppm or below, depending on the regulatory body. The recommended exposure level by the US National Institute for Occupational Safety and Health is significantly lower at 100 ppb and the Committee for Risk Assessment of the European Chemical Agency has recommended an occupation exposure limit of only 50 ppb. For ambient exposure, the European commission has set a target limit value of 1.5 ppb, evaluated as a yearly average. High sensitivity trace gas detectors for benzene are thus in high demand and for accurate monitoring a sub-ppb detection limit is needed for accurate quantification.