Video Simulations of PM2.5 Levels in Europe and the United States, Choirat

Evolution of PM2.5 levels in Europe and the United States

The following videos depict the evolution of PM2.5 levels from 1998-2015 in Europe and the United States. The same color scales are used for both videos. As shown, there are drastic improvements in air quality for the whole US, while air quality in Europe does not show much improvement and some areas, including Milan, worsen.
Video Author: Christine Choirat
Data Sources: Atmospheric Composition Analysis Group, Dalhousie University (
PI: Randall Martin (
Method: Global chemical transport model (GEOS-Chem) to estimate ground-level PM 2.5 from satellite-observed ‘column’ aerosol loading.




Smog Episode in Milan, Italy

The following video simulates PM10 diffusion during a smog episode in Milan on December 15, 2015. Milan is surrounded by mountains and the high pressures contribute to PM stagnation. As shown in the video, PM remains concentrated in low-lying areas and diffusion is restricted by the mountainous regions surrounding the city.
Video Author: Christine Choirat
Simulation: HYSPLIT diffusion of PM10 on December 15, 2015 in Milan (smog episode)
File: smog.R
HYSPLIT: Apple-based HYSPLIT, version 4 (
HYSPLIT R interface: