We measured the radiocarbon (C-14) content of organic carbon (OC) samples from two locations in the Netherlands, the urban location of Amsterdam and the coastal location of Petten. PM10 samples were collected in Amsterdam and total suspended particles were collected in Petten using high volume samplers. The C-14/C-12 fraction in the samples is reported as fraction modern ((FC)-C-14). It can be used to roughly estimate the contribution of fossil sources to OC, since (FC)-C-14 of fossil fuels is 0, whereas biogenic and wood burning sources are characterized by Fit values close to 1. At the coastal location organic carbon has higher (FC)-C-14 values (0.83 +/- 0.04 standard uncertainty) than at the urban location (0.68 +/- 0.05). A fraction modern of 0.68 is in the range of (FC)-C-14 values published for OC of other European urban areas (0.68-0.81). The coastal (FC)-C-14 of 0.83 agrees well with measurements at the coastal location of Mace Head, even though in Mace Head measurements were made on particles smaller than 1.5 mu m (PM1.5). A (FC)-C-14 of 0.83 is on the lower end of (FC)-C-14(OC) values estimated for continental background sites in Europe. Fossil sources might be contributing slightly more to organic carbon in the Netherlands than in other European regions. However, a bigger data set is needed to substantiate this finding. On average, fossil fuel combustion is responsible for approximately 40% of the organic carbon in Amsterdam and approximately 20% at the coastal location. At the coastal location, (FC)-C-14 was clearly lower than average when polluted air masses reached the measurement site, whereas in the urban area, air mass history did not have a strong influence on (FC)-C-14. (C) 2013 Elsevier Ltd. All rights reserved.