Air pollution exposure in European cities: The 'EXPOLIS' study

Epidemiological literature of the 1990's has revealed surprisingly large public health impacts associated with present common air pollution levels in North American and European cities. Any causal explanation of the health effects of air pollutants must go through exposure, yet no large, population based air pollution exposure studies have been conducted in Europe, and consequently no European database of air pollution exposures of urban populations has existed until now. EXPOLIS is a European multicenter study for measurement of air pollution exposures of working age urban population during workdays. The selected urban areas are Athens, Basel, Grenoble, Helsinki, Milan and Prague. The main objectives of EXPOLIS are: - To assess the exposures of European urban populations to major air pollutants. - To analyse the personal and environmental determinants and interrelationships to these exposures. - To develop an European database for simulation of air pollution exposures. These objectives were pursued by measuring the personal exposures, home indoor and outdoor and workplace levels of particles smaller than 2.5 μm in aerodynamic diameter (PM_2.5), volatile organic compounds (VOCs) and carbon monoxide (CO) of approximately 500 subjects representing the adult population of the selected cities. The field work continued from fall of 1996 to winter of 1997-1998. Identical sampling equipment, operating procedures, time-microenvironment-activity diaries, questionnaires, database and data entry tools were used in each center. To assure comparability of the data from the 6 cities in 6 countries, a strict quality assurance/quality control (QA/QC) protocol was established and the field work was supervised by the QA Unit of KTL. Standard operating procedures SOPs were prepared for all subject, laboratory and field procedures, and the EXPOLIS field teams were trained in three joint workshops. VOC laboratory analyses were intercalibrated by the European Commission/Joint Research Centre (EC/JRC) Environment Institute in Ispra. Other techniques were intercalibrated between the teams. This paper describes the main design features of the European Union 4th Framework RTD Programme funded multicenter study; Air Pollution Exposure Distributions of Adult Urban Populations in Europe (EXPOLIS). The EXPOLIS Centers are KTL-(coordinating center) in Helsinki, University of Athens, University of Basel, University Joseph Fourier in Grenoble, University of Milan, Regional Institute of Hygiene of Central Bohemia in Prague, VTT (Finnish State Technical Research Center) in Helsinki, and RIVM (Dutch National Public Health Institute) in Bilthoven. More detailed descriptions of the materials, methods and results of this large, multicenter and multidimensional study will be published later in more focused articles.