European modeling of atmospheric copper, iron and manganese as key players for aerosol toxicity

Exposure to air pollution, especially aerosols, can lead to adverse health effects. Particle toxicity has been generally linked to its mass concentration. However, toxicity is determined by the chemical composition of the aerosol, which varies greatly depending on pollution sources. Reactive oxygen species (ROS) can be formed in the lung when particles are inhaled and can trigger inflammatory processes. Transition metals strongly contribute to ROS, among which copper, iron and manganese. However, these metals are generally not included in current emission inventories and chemistry-transport models. Thus, to ultimately model aerosol toxicity, it would be necessary to add these three metals into a chemistry-transport model, and use it to provide inputs to a lung chemistry model (Lelieveld et al, 2021).

Country-wise copper emissions are available from the EMEP database (https://www.ceip.at/) for the majority of European Union countries. Methods for evaluating emissions differ from country to country, and it is necessary to homogenize them to standardize emissions, at least for the main emitting countries around France which is the main target of the study. For iron and manganese, European scale inventories do not exist yet. Data from the French Citepa and ADEME, from EMEP reports, SPECIEUROPE and a bibliography of 16 references were used to build these two bottom-up inventories. Many sources have been studied: abrasion of tires, brakes and road for the road transport sector, wear of catenaries, brakes and rails for the rail sector, combustion of coal, biomass and of petroleum, the burning of motor oils, and the incineration of waste.

Also, long term measurements from several dozens of rural, urban and traffic sites were collected to build a large database. These data come from EBAS website (https://ebas-data.nilu.no/), UKAIR website (https://uk-air.defra.gov.uk/data/), CARA program (Favez et al., 2021), the Spanish IDAEA and the French Atmo Auvergne-Rhône-Alpes and Marseille-Longchamp. Fe/Cu and Mn/Cu ratios were calculated for both the bottom-up emission inventories and measurements data. As these ratios turned out to be significantly lower in emission inventories, observed ratios were used to adjust Fe and Mn emissions from Cu ones.

Using these two inventories, emission ratios with coarse particles for each country and sector were created and applied to the spatialized particles emission data. We then implemented the obtained spatialized Cu, Fe and Mg emission inventories into the CHIMERE chemistry-transport model, to simulate ambient copper, iron and manganese mass concentrations in Europe for the year 2014.