We have recently shown that inhabitants of two polluted areas in Kosovo display more DNA damage (strand breaks in blood cell DNA) than do residents of a cleaner area. Here, we present additional analyses of these data and discuss additional data sets from Kosovo. Based on our data as well as the available data from other authors, age and sex-related differences in DNA damage or in susceptibility to DNA-damaging agents in the environment should be carefully considered when designing biomonitoring studies and when carrying out statistical analysis of the data.