How can i create this grainy, blurred effect?

I found this piece of work by Alexis Jamet and i'm trying to figure out how i can create an image witha similar blurred, grainy effect. I'm not sure whether the individual shapes are created with a specific paintbrush or whether they are vector shapes which have been moved to photoshop and have been given some kind of effect or filer? 

Any help as to how i could achieve something similar would be great!