How atmospheric simulation chambers can help to investigate the impact of air quality on health

SummaryUsing CESAM, an atmospheric simulation chamber (cesam.cnrs.fr), we have developed a totally innovative platform for exposing mice to realistic atmospheric conditions. Here we present the first toxicological analyses of the organs of these mice after 48 hours to several days of exposure, carried out as part of feasibility experiments aimed at testing this experimental concept. This platform has received funding from the European Union’s Horizon 2020 research and innovation programme through the EUROCHAMP-2020 Infrastructure Activity under grant agreement N° 730997, and is now supporting the new REMEDIA H-2020 project (call H2020 “Exposome”) IntroductionThe World Health Organization (WHO) estimated that there were 3.7 million premature deaths due to air pollution in 2014, and confirmed that air pollution is the greatest environmental risk to health (responsible for a loss of more than 3% of productivity).The studies conducted so far show that the effects of air pollution on health depend not only on the quality of the surrounding air, but also on the subjects exposed and their individual vulnerability (asthma, obesity, period of life, etc.). Despite the evidence on the adverse health effects of exposure to air micro-pollutants, there are still uncertainties about the nature of these effects, and progress need to be made on their quantification. This limitation of knowledge is mainly attributed to the complexity of the polluted atmospheres, and to the great difficulty to model the impact of realistic situations of exposure. MethodologyThe innovative approach we set up is to realistically simulate, at the laboratory, the atmospheric mixture in all its complexity, thus keeping the ability to control, reproduce and carefully characterize the experimental conditions. We used the CESAM chamber (4.2 m3 stainless steel atmospheric simulation, evacuable down to a few 10-7 atm, temperature controlled between +15°C and +60°C) in order to study the myriad of products arising from the atmospheric oxidation of primary organic compounds.The experimental protocol consists in the continuous injection of relevant mixtures of primary pollutants (mainly nitrogen oxides, organic compounds from a representative mix of anthropogenic emissions, sulphur dioxide, soot, inorganic salts and potentially mineral dust particles if needed - e.g. to simulate Beijing’s atmosphere) at low concentrations (ppb levels) in air in the CESAM simulation chamber operated as a slow flow reactor. The residence time of simulated air parcels in the experimental volume is fixed to 4 hours, in order to represent air masses of regional scale. During this time the synthetic mixture is exposed to an artificial solar irradiation, allowing secondary pollutants such as ozone, nitric acid, formaldehyde, peroxyacetyl nitrate as well as complex polyfunctional organics including SOA to be produced and to reach their chemical steady state. Mice are exposed to constant flows of such a mixture during time scales of week to address their effects on health. ConclusionsHere we present the first toxicological analyses related to organs/tissue of these mice after exposure of 48h to several day, carried out with a representative atmosphere of Beijing or a representative atmosphere of Paris. ReferencesColl P. et al., 2018, WIT Transactions on Ecology and the Environment, 230.