Member states of the European Union have to maximize recycling. The current, Danish cardboard recyclingsystem can be improved by increasing the kinds of cardboard products that can be recycled toinclude e.g. used beverage cartons and pizza boxes (i.e. an expanded cardboard fraction (ECF)). This studyaims to obtain knowledge about exposure to airborne endotoxin and microorganisms at species level atdifferent collection frequencies of ECF, and whether an increase in waste sorted fractions means that eachwaste fraction is collected less frequently. Bacterial and endotoxin concentrations were associated significantlywith temperature inside the waste containers and endotoxin and fungal exposures with collectionfrequency. The concentration of fungi was highest at the truck back and for reduced collection frequencies.The geometric mean diameters of particles with bacteria were between 3.0 and 5.2 lm and withfungi between 3.8 lm and 6.0 lm. In total, 81 and 25 different bacterial and fungal species were foundat the waste receiving plant, respectively. Work with ECF caused exposures to food-related microorganisms(e.g. Arthrobacter arilaitensis and Penicillium camemberti), potential pathogens (e.g. Bacillus cereus,Salmonella sp. and P. expansum), and commensal bacteria. Bacillus cereus and Salmonella were found inthe particle size fraction often being swallowed. Workers collecting EFC will be at risk of being exposedto microbial species that normally are related to residual waste. It seems to be advisable with an EFC collectionfrequency shorter than eight weeks. However, introduction of new waste fractions has generallybeen associated with reduced collection frequencies.