Ammonia and PM_2.5 Air Pollution in Paris during the 2020 COVID Lockdown

Camille Viatte (1) , Jean-Eudes Petit (2, 3) , Shoma Yamanouchi (4) , Martin Van Damme (5) , Carole Doucerain (1) , Emeric Germain-Piaulenne (1) , Valérie Gros (2, 3) , Olivier Favez (6) , Lieven Clarisse (5) , Pierre-François Coheur (5) , Kimberly Strong (4) , Cathy Clerbaux (5, 1)

1 TROPO - LATMOS
2 LSCE - Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette]
3 CAE - Chimie Atmosphérique Expérimentale
4 Department of Physics [Toronto]
5 SQUARES - Spectroscopy, Quantum Chemistry and Atmospheric Remote Sensing
6 INERIS - Institut National de l'Environnement Industriel et des Risques

During the COVID-19 pandemic, the lockdown reduced anthropogenic emissions of NO2 in Paris. NO2 concentrations recorded in 2020 were the lowest they have been in the past 5 years. Despite these low-NO2 levels, Paris experienced PM2.5 pollution episodes, which were investigated here based on multi-species and multi-platform measurements. Ammonia (NH3) measurements over Paris, derived from a mini-DOAS (differential optical absorption spectroscopy) instrument and the Infrared Atmospheric Sounding Interferometer (IASI) satellite, revealed simultaneous enhancements during the spring PM2.5 pollution episodes. Using the IASI maps and the FLEXPART model, we show that long-range transport had a statistically significant influence on the degradation of air quality in Paris. In addition, concentrations of ammonium (NH4+) and PM2.5 were strongly correlated for all episodes observed in springtime 2020, suggesting that transport of NH3 drove a large component of the PM2.5 pollution over Paris. We found that NH3 was not the limiting factor for the formation of ammonium nitrate (NH4NO3), and we suggest that the conversion of ammonia to ammonium may have been the essential driver.

Mots clés: particulate matter; ammonia; air pollution; COVID-19; Paris

Domaines: Océan, Atmosphère

Camille Viatte, Jean-Eudes Petit, Shoma Yamanouchi, Martin Van Damme, Carole Doucerain, et al.. Ammonia and PM_2.5 Air Pollution in Paris during the 2020 COVID Lockdown. Atmosphere, 2021, 12, pp.160. ⟨10.3390/atmos12020160⟩. ⟨insu-03124156⟩