Cellular responses after exposure of lung cell cultures to secondary organic aerosol particles

The scope of this work was to examine in vitro responses of lung cells to secondary organic aerosol (SOA) particles, under realistic ambient air and physiological conditions occurring when particles are inhaled by mammals, using a novel particle deposition chamber. The cell cultures included cell types that are representative for the inner surface of airways and alveoli and are the target cells for inhaled particles. The results demonstrate that an exposure to SOA at ambient-air concentrations of about 10(4) particles/cm(3) for 2 h leads to only moderate cellular responses. There is evidence for (i) cell type specific effects and for (ii) different effects of SOA originating from anthropogenic and biogenic precursors, i.e. 1,3,5-trimethylbenzene (TMB) and alpha-pinene, respectively. There was no indication for cytotoxic effects but for subtle changes in cellular functions that are essential for lung homeostasis. Decreased phagocytic activity was found in human macrophages exposed to SOA from alpha-pinene. Alveolar epithelial wound repair was affected by TMB-SOA exposure, mainly because of altered cell spreading and migration at the edge of the wound. In addition, cellular responses were found to correlate with particle number concentration, as interleukin-8 production was increased in pig explants exposed to TMB-SOA with high particle numbers.

Is there a common pattern of future gas-phase air pollution in Europe under diverse climate change scenarios?

Climate change alone influences future levels of tropospheric ozone and their precursors through modifications of gas-phase chemistry, transport, removal, and natural emissions. The goal of this study is to determine at what extent the modes of variability of gas-phase pollutants respond to different climate change scenarios over Europe. The methodology includes the use of the regional modeling system MM5 (regional climate model version)-CHIMERE for a target domain covering Europe. Two full-transient simulations covering from 1991–2050 under the SRES A2 and B2 scenarios driven by ECHO-G global circulation model have been compared. The results indicate that the spatial patterns of variability for tropospheric ozone are similar for both scenarios, but the magnitude of the change signal significantly differs for A2 and B2. The 1991–2050 simulations share common characteristics for their chemical behavior. As observed from the NO2 and α-pinene modes of variability, our simulations suggest that the enhanced ozone chemical activity is driven by a number of parameters, such as the warming-induced increase in biogenic emissions and, to a lesser extent, by the variation in nitrogen dioxide levels. For gas-phase pollutants, the general increasing trend for ozone found under A2 and B2 forcing is due to a multiplicity of climate factors, such as increased temperature, decreased wet removal associated with an overall decrease of precipitation in southern Europe, increased photolysis of primary and secondary pollutants as a consequence of lower cloudiness and increased biogenic emissions fueled by higher temperatures.