, 2012), whereas low MVF was associated with high levels of ambient PM2.5 on the preceding two days (Pope et al., 2011). The indoor PNC levels in our study partly originated from the use of candles (Bekö et al., 2013), which might a have limited effect on vascular function. Moreover, MVF and other measures of endothelial function might be most susceptible to ambient PM from traffic-related sources due to a combination of small size and chemical composition. We found a positive association between levels of HbA1c and indoor PNC, but not with outdoor PNC and PM mass, which could be consistent with long-term PS-341 effects related

to indoor exposure. The level of HbA1c is an indicator of the average level of blood glucose over the previous 2–3 months and related to the risk of diabetes and cardiovascular disease in the general population (Jorgensen et al., 2004). A recent study investigating the relationship between long-term air pollution exposure and risk factors for cardiovascular diseases INCB024360 mw found that the HbA1c level was positively associated with the levels of PM, O3 and NO2 (Chuang et al.,

2011). Similarly, the risk of diabetes was associated with long-term exposure to traffic-related air pollution in Denmark (Andersen et al., 2012). Such adverse effects of air pollution could be related to chronic low-grade systemic inflammation. We found that indoor levels of PNC and endotoxin in settled dust were inversely associated next with lung function with a 2% decrease per IQR change for both these pollutants. This dual association between PNC and endotoxin and lower lung function could be related to the ability of indoor PM as allergen carrier

(Ormstad, 2000). The composition of indoor UFP may play an important role in their adverse health effects, since around 20% of airborne particles are biological components, and some of them e.g. endotoxin may contribute to PM toxicity (Degobbi et al., 2011). However, the bioaerosol levels in Danish homes can vary considerably, depending on occupancy and season (Frankel et al., 2012 and Madsen et al., 2012). The association between indoor exposure to allergens and lower lung function is well known for individuals with respect to respiratory allergies or asthma (Sublett, 2011). Although our subjects did not suffer from asthma, the association between lung function and exposure to endotoxin in the home is consistent with results of previous studies on the prevalence of asthma in adults and children (Michel et al., 1996 and Rabinovitch et al., 2005). There are only few investigations on the association between exposure to indoor-levels of PM and lung function, although it has been hypothesized to be an important determinant for respiratory symptoms and diseases including asthma (Delfino, 2002 and Weisel, 2002). Most studies included subjects with existing disease and none included exposure in terms of PNC.