I am thinking about buying air purifier as pollution is high in my city. Going through the specifications of HEPA filters, I found that they block particulate matter of 2.5. PM 2.5 contains dust and other fine particles. Googling tells me that their size is around 2.5 micrometers.
My question is: Do pollutants such as sulfur oxides and nitrogen oxides (and related compounds) fall into this category, specifically in regards to size?