The confinement, the decrease of the automobile traffic, the shutdown of certain industrial activities, in particular, have resulted in reduced pollution and improved air quality in many cities. Yet, and very oddly, this has not been the case in Paris and its region last week. Why is that so?
In fact, the road traffic has fallen from 80% in the Ile-de-France since the implementation of containment measures. But at the same time, the air quality has not improved, with indices published by the monitoring network Airparif, which showed no regression of the pollution.
Worse, the curves of levels of fine particles and nitrogen oxide have increased some days. So, last Wednesday, the pollution indicator is mounted at 61 in the Hauts-de-Seine, while the air is regarded as “weakly polluted” up to 50.
The weather in question
In a report, Airparif has explained this situation by “a spring weather favouring chemical reactions with the formation of particles so-called secondary, from gas : oxides of nitrogen (primarily related to the heaters), and ammonia (from agricultural activities)”.
“This situation highlights the contribution of different sources to the pollution and the specific role of weather conditions”
Karine Léger, director of Airparif, explained as well as the weather conditions, i.e. low temperatures in the morning and the sun high in the day, promote the formation of these particles. At the same time, the confinement has caused an increase in the consumption of heating, including wood. “We may also refer to the agricultural activities with the application that take place at this time”, highlighted Karine Léger.
Particles related to traffic are very low
Airparif was at the same time that “the levels of particulate traffic-related are very low,” and that “the observed increase would have been much more significant with normal traffic conditions”.
Towards a better
The air quality is expected to improve this week in the Ile-de-France, notably thanks to the return of the wind, which removes part of the pollution particles.