There is a lot of political pressure in Paris to push out diesel motors, which are often the main source of summer pollution peaks. This
one actually has another origin: (French source) http://www.airparif.asso.fr/ac... .
There is actually a cloud over much of north Europe, not just Paris. The origin is firstly agricultural.
Its mostly ammonium nitrate from spring fertilizer spreading. The second source is wood burning out in the country. Diesel
is the third source in this outbreak.
The real political problem is the impossibility of doing anything against big-agro, not diesel. (Similar problems in France
also occur with water pollution -- impossible to regulate)