PEOPLE campaigns were completed in six cities, namely; Brussels and Lisbon (22 October 2002), Bucharest and Ljubljana (27 May 2003), Madrid (3 December 2003) and Dublin (28 April 2004). The first stage of the project was accomplished with benzene as the pollutant considered. In Ljubljana, outdoor measurements were extended to include particulate matter and a number of polycyclic aromatic hydrocarbons. In Madrid, measurements were further supplemented with an assessment of the heavy metal content of particulate matter. In Dublin, particulate monitoring also included human exposure and indoor environments.
Mapping of outdoor measurements indicate areas of highest concentrations being associated with major road intersections. Transportation was identified as the dominant source of benzene in all six cities that were studied. Background levels of benzene measured on the day of the campaign, and the subsequent estimation of the yearly average city levels, revealed that PEOPLE cities are in compliance with the Directive 2000/69/EC, with the exception of Bucharest.
The levels at ambient background sites, situated at the types of locations used for air quality directive monitoring, were comparable to the air quality of the control groups of this study, namely the homes of people that do not smoke and the personal exposure of people who neither commute to a workplace or smoke. City background benzene levels are therefore applicable as an indicator of human exposure for non smoking people that do not commute to work and are not exposed to indoor sources. In general, city background sites represent the lowest level of exposure. Higher levels of exposure were related to the different categories that were used in the project. The smoking group had the highest level of exposure. For the commuting categories the car user group has the highest exposure levels. The level of exposure of children was similar to that of the commuting categories. Some individuals and locations reported extremely high concentrations. Further analysis of the movement diaries from individuals whose measurements were identified as outliers could not always explain the elevated benzene concentrations. In these cases either the presence of unknown sources or unusual proximity to known sources are possible explanations of elevated exposure levels.
The basic results have revealed that human exposure, of commuters and smokers, to the air pollutant benzene is higher, by a factor of two, than concentrations reported at urban background monitoring sites. This is due to the influence of traffic and smoking emission sources. When the commuters are considered together as a group, excluding the smoking participants and control groups, comparison with ambient city background data, for all six cities, indicates that a ratio of approximately 1.5 (commuters/background) for the median benzene concentrations.
Citizens that are exposed to indoor emissions such as smoking, or move and work in proximity to traffic, can be expected to receive much higher pollutant exposures. Indoor locations that were influenced by smoking sources reported relatively high concentrations. While indoor pollution levels are usually determined by the external air quality, it is clear that the presence of indoor sources, such as smoking, can elevate pollution concentrations. This was evident for a number of individual sites. The highest indoor concentrations were measured in bars and inside taxis that travelled within traffic for the sampling period.