investigator choice

All COPD patients with a diagnosis of acute exacerbation in emergency room in University Hospital of Amiens-Picardie between 01/01/2017 and 31/12/2017. The investigator will collect for each patient the home address and the work address. The duration of 1 year was chosen to take into account seasonal variations. In parallel, a daily report of the rate of ozone, particles (PM2.5 and PM10), dioxide nitrogen but also odours and pollens will be done by ATMO Picardie.

Inclusion Criteria:

• All COPD patients with a diagnosis of acute exacerbation of COPD in the emergency room. The definition of COPD and acute exacerbation are the official definition of the Société de Pneumologie en Langue Française.

Exclusion Criteria:

• no exclusion criteria

The primary endpoint is the number of exacerbations of COPD corresponding to the variable of interest to be explained. The other variables are the explanatory variables (air quality data PM2.5, PM10, NO2, O3 as well as pollen data, seasonal variations, influenza epidemic and olfactory nuisance). The final diagnosis will also be collected.