Air quality is a major problem in many areas, especially in urban districts where traffic is one of the main pollutant sources. In Western Europe between 30 and 60% of volatile organic compounds (VOC) originate from traffic. Benzene, which is allowed in gasoline up to 5%, is an established human carcinogen and the personal exposure to benzene has been the target for environmental research in Sweden during the latest years.

In many developed countries monitoring networks that measure concentrations of volatile organic compounds has been established. These networks consist of fixed point monitoring stations. Fixed-point monitoring stations are well suited to evaluate the general pollution climate and to monitor trends, but they have shown not to represent the personal exposure of the general population.

In this study, the personal exposure to benzene in different adjacent urban environments in the city of Göteborg was investigated, in order to describe:

 The magnitude and spatial variation of benzene  The relationship between mobile (personal exposure) and stationary measurements  The influence of traffic intensity, land use, measuring height, wind speed and atmospheric turbulence  Seasonal variation

The city of Göteborg is with 700 000 inhabitants the second largest city in Sweden. Three adjacent urban environments were selected for the study. The first is a large urban park (150ha) with almost no traffic, the second is a densely built-up area with high traffic intensity (1100 cars per hour) and the third is a dense built-up area with limited traffic (30 cars per hour).

Simultaneous measurements were performed in the three areas at typical heights of a child (1.0m) and an adult (1.5m) between 1100 and 1400 hours LST. Twelve case studies were carried out, of which eight during summer and four during winter. Each person was instructed to make diary notes about time and activity pattern, and they were asked to avoid passive smoking. The samplers consist of Tenax-ATD (Automatic Thermal Desorption) tubes for active sampling of VOC, attached to Gilian Universal Tube Holder-pumps (LFS 113D). Three different VOC, benzene, toluene and xylenes was measured and analysed.

The preliminary results showed large differences in personal exposure to benzene between the three different adjacent urban environments both during summer and winter. The study also confirms the difficulties to select representative stationary measuring points in environments with many and large sources. The difference in personal exposure to benzene between the two measurement heights was insignificant, indicating that the air in the street canyons is well mixed.

More results and its implication will be presented at the conference.