Determination of the sources of Indoor PM_(2.5) in Amsterdam and Helsinki

摘要

Daily PM_(2.5) samples were repeatedly collected (1-8 times) in the homes of elderly nonsmoking individuals with coronary heart disease in Amsterdam, The Netherlands (33 individuals) and Helsinki, Finland (44 individuals). Sources of indoor PM_(2.5) were evaluated using a two-way multilinear engine model. Because the indoor elemental data lacked a traffic marker, separation of traffic related PM was attempted by combining the indoor data with fixed site outdoor data that also contained NO. Six outdoor sources, including long-range transport (LRT), urban mixture, oil combustion, traffic, sea-salt, and soil were identified, and three indoor sources were resolved: resuspension, potassium-rich and copper-rich sources. The average contribution of the indoor factors was 6% (1.1 μg m~(-3)) and 22% (2.4 μg m~(-3)) in Amsterdam and Helsinki, respectively. The highest longitudinal correlations between source-specific outdoor and indoor PM_(2.5) concentrations were found for LRT and urban mixture; the median R was above 0.6 for most sources. The longitudinal correlations were lower in Helsinki than in Amsterdam. Indoor-generated PM_(2.5) was not related to ambient concentrations. We conclude that using outdoor and indoor data together improved the source apportionment of indoor PM_(2.5). The results support the use of fixed site outdoor measurements in epidemiological time-series studies on outdoor air pollution.