Does a mouth mask help to decrease inhalation of particulate matter?

A simple paper mask does absolutely not protect suffieciently against fine particles.

Protection masks that have to be used by labourers exposed to particulate matter do exist though. These masks consist of filtering and absorbing materials that meet the demands as described in European Directive 89/686/EEC, regarding personal protective equipment.

However, it would be excessive to wear such masks on the street (be it in our country). Only people suffering from certain diseases or laborers that are continually exposed to concentrations of particulate matter may benefit from wearing such masks.