Are masks effective against PM 2.5?

N95 masks have been noted as effective in reducing the risk of inhaling PM 2.5, though not perfectly. They are recommended especially for those who must be outdoors in areas with poor air quality, like farm workers or those exposed to wildfire smoke. Dr. Kari Nadeau emphasized that while no mask can completely stop these particles, which are small organic molecules, an N95 mask provides significant protection compared to no mask at all 1.