Air pollutant levels in Denmark are generally moderate due to a windy climate and moderate local emissions. Despite this, a series of epidemiological studies point to air pollution as a cause of severe adverse health effects in the Danish population. Significant relationships between air pollutant levels and negative health outcomes in the Danish population have thus been found for end points like: stroke, lung cancer, chronic obstructive pulmonary disease, asthma in adults, wheeze in infants, asthma hospital admissions in children, diabetes, and vascular function in the elderly. These findings have been possible as a result of combining the unique Danish health registry data with detailed exposure assessments based on routine monitoring data and/or high resolution exposure modelling. In the following we will have focus on exposure assessment methodologies. Some of the airborne pollutants that are not all well described, and for some pollutants the population based assessments are mainly indicative and incomplete. This especially counts for all airborne allergens. Today about 21% of the Danish population suffer from allergenic rhinitis and a proportion of these are affected by aeroallergens that are associated to specific pollen. There are many different species of airborne pollen in our ambient environment and a fraction of these negatively affects human health. However, this information on the exposure of allergenic pollen is either limited or not available. Initiatives have been taken that aim to bring pollen monitoring up to the same level as general air pollution monitoring programmes have today, including new observational methods for exposure estimates and the use of atmospheric models. As already stated the following chapter describes and discusses the applied methodologies and some of the main findings of the Danish studies on air pollution and pollen exposure assessment, and the associated negative health impact in the Danish population.