Officially, Paris and Ile-de-France experienced only one episode of pollution this winter. According to readings from Airparif, the organization responsible for monitoring air quality, it occurred on February 8 with a peak of fine particles known as PM10 (with a diameter between 2.5 µm and 10 µm ) at 62 µg/m3, i.e. above the alert threshold of 50 µg/m3 over twenty-four hours.
However, Paris was affected by several persistent episodes of PM2.5 fine particle pollution (less than 2.5 µm) between November 2017 and January 2018. But unlike PM10, nitrogen dioxide, ozone and sulfur dioxide, excessive concentrations of PM2.5 do not trigger alert procedures.
Full article (Fr) : Le Monde