Organochlorine pesticides (OCPs) have been used to preserve the integrity of historical buildings or to protect collections of artefacts at potentially large volumes and often without detailed application records. Previous research has focused on the efficiency of remediation at contaminated sites (where identified), as well as improvement of preservation techniques and workplace health and safety. Few studies have assessed the human health risks from occupational exposure to OCPs in buildings of cultural and historical importance. Thus, potential risks may remain unidentified. In the present study, OCPs in indoor air were measured in a baroque theatre and a natural history museum in the Czech Republic, both of which had suspected past indoor application. In the theatre attic p,p'-dichlorodiphenyldichloroethylene (p,p'-DDE) levels in air were up to 190 ng m(-3), confirming past indoor use of p,p'-dichlorodiphenyltrichloroethane (p,p'-DDT). There was also evidence of gamma-hexachlorocyclohexane (gamma-HCH) use in the theatre (max gamma-HCH in air of 56 ng m(-3)). Yet, the cancer risk (CR) from occupational exposure via inhalation (Exp(i)) to OCPs in the theatre was low (CR < 4.0 x 10(-6)). gamma-HCH was found at elevated levels in air of the museum (max gamma-HCH in air of 15,000 ng m(-3)). CR from Exp(i) in the museum was moderate to high (>1 x 10(-4)). Our results show the CR through Exp(i) to OCPs in buildings, such as museums can still be significant enough to warrant mitigation measures, e.g., remediation.