N: A controlled inhalation diesel exhaust exposure facility with dynamic feedback control of PM concentration. Inhal Toxicol 2008, 20:49–52. doi:10.1186/1743-8977-10-7 Cite this article as: Krishnan et al.: A randomized cross-over study of inhalation of d

A facility has been assembled that provides a controlled inhalation exposure to freshly diluted and mixed diesel exhaust using a diesel engine under load and a two-stage exhaust dilution system with dynamic feedback control. The concentrations of particulate matter less than 2.5 µm in diameter (PM2.5), particulate carbon, and gaseous pollutants including carbon monoxide and oxides of nitrogen (NOx) have been characterized and the exposure conditions have been found to be both stable and reproducible. Control of the PM2.5 concentration at intended levels relies on the relatively linear relationship between particle light scattering and exhaust particle mass concentration. While the exposure system does not entirely replicate diesel exhaust conditions in the atmosphere due to the relatively low ratio of nitrogen dioxide to total NOx, the fine particulate matter size distributions are quite similar to those of aged diesel exhaust. The facility enables study of the relationship between diesel exhaust and cardiovascular and respiratory health effects in human and animal models. We briefly describe a facility that provides a controlled in-halation exposure to freshly diluted and mixed diesel exhaust (DE) in order to study the relationship between DE and car-diovascular and respiratory health effects in human and animal models. Unique aspects of this facility, especially for human ex-posure, are engine operation under load and two-stage dilution system with dynamic control of the exposure concentration. In contrast, other research groups have produced controlled expo-sures for human inhalation studies using diesel exhaust fro