Health Risk Assessment of Indoor Volatile Organic Compounds (VOC) considering Long-term trend of VOC

Background: The indoor air quality is among other things determined by air pollutants such as volatile organic compounds (VOCs) which are associated with health effects. The severity of these health effects depends on the kind and part of the specific chemicals within the VOC group. Since the 90th the expected health risk has been evaluated by means of the VOC sum concentration under the assumption of a fixed composition with a clear defined part of every single VOC. The question is whether the VOC sum and whether the share of individual VOCs have been changed over the recent years. Methods: Indoor VOCs were measured within the frame of epidemiological studies from 1994 until 2008. Additionally, a large number of apartments were investigated depend on inquiries by physicians, health offices, or inhabitants in a period from 2009 to 2014. The human health risk was assessed both based on currently valid criteria and based on adapted criteria considering potential composition of the VOC pattern. Results: A substantial reduction in the sum of VOCs (about 60%) could be demonstrated caused by a clear decreasing trend of aromatics and alkanes. No such changes could be observed for cycloalkanes, chlorinated hydrocarbons and terpenes. The resulting pattern of VOC is quite different compared with the start situation in 1994. The part of terpenes at the VOC sum increased by two from approximately 25% (1994) to 55% (2014). Due to the decrease of the VOC sum, the human health risk might be underestimated if the VOC sum is the only criterion. Conclusions: Based on our findings special attention should be paid to groups of VOCs and/or single VOCs.