This claim is made in an article published on december 18th on the online version of the French newspaper Le Monde.

Des études scientifiques ont estimé que près de 1,4 million de Chinois meurent chaque année, directement ou indirectement, de la pollution de l’air.

Which translates to

Some scientific studies estimated that almost 1.4 million Chinese people die each year, directly or indirectly, from air pollution.

This claim is made without referring to any source. It sounds like a huge number to me, so I'd like to know if this is true.