Ultrafine particles (UFP) have been identified as having adverse effects on human health. It is, therefore, important to assess exposure to specific UFP-emitting sources. Assessment of UFP concentrations are very time and cost intensive in large study populations. Modelling is, therefore, a convenient tool for estimating UFP concentrations. To date, models have focussed on ambient air concentration without taking local sources within the breathing space of the participant or individual habits into account. In order to fill this gap, this study incorporated a population of 22 individuals equipped with a UFP sampler for a period of 48 hours so as to assess personal exposure to UFP and to identify major UFP-emitting sources. With the help of a diary and questionnaire, the UFP data collected could be allocated to specific sources. Furthermore, information from the questionnaire was used in order to develop a personal UFP exposure model which included local and ambient UFP-emitting sources. This study was able to identify differences in UFP concentrations for specific UFP- emitting sources. Moreover, it was able to identify major contributors to UFP, namely cooking and travelling by car. The data collected in this study, with an overall availability of 912 hours, matches values found in the literature. With respect to UFP modelling, it is seen that the data collected was highly variable for the same UFP-emitting source within an individual and within the entire study population. Moreover, a theoretical model was developed for the assessment of personal UFP exposure. Due to high variability of collected data and the small study population, a validation of this model could not be conducted. This study showed that a higher level of detail is necessary in order to complete the personal UFP model and to perform a validation. This means, that more information on cooking and cleaning methods, such as, boiling, frying, dusting or vacuuming, is needed in order to allocate UFP concentrations to specific exposure situations.