3M 9332 FFP3 would be one of a desirable one.
It is not cheap stuff. Moreover in Japan they are sold for triple price of following web shop. Only one mask for 20 dollars or so.
If you prefer more reasonable one. 3M 9211 would be good option.
I have a reason to recommend these masks. Edano, Chief Cabinet Secretary selected it. It was April 17 that he visited the Fukushima prefecture for the first time after the Fukushima nuclear accident. He was wearing the 3M mask. some say it was 9332, the other say it was 9211. As I am not mask professional, I don't know which one is correct one, so I am writing these 2 masks there.
He inspected the area within 20 kilometers of the plant, from the car. He got out of the car and greeted the ppl working there, at least 5 minutes. When surrounded by the ppl working there who were wearing ordinary mask, the mask worn by the careful 5-minutes visitor was said one of them.