Why is the air quality “poor” this Wednesday in the north of Haute-Vienne?

Green to the south of Haute-Vienne, then yellow going up and even red. According to the daily map provided by the air quality observatory in Nouvelle-Aquitaine, Atmo Nouvelle-Aquitaine, the air quality is “degraded” and even “poor” – for the northern end – on a part of Haute-Vienne this Wednesday, January 15.