A self-powered, personally wearable air purifier includes a sequence of packed bed filter media packets having filter media therein of specifically targeted types that will absorb those ambient air pollutants that have been identified as being particularly dangerous to human health. A HEPA filter is included for the removal of particulate matter that will have adhered thereto many of such pollutants. Media types can be selected to meet different environmental circumstances, including normal highway or city center air, or terrorist attacks of chemical, biological or "dirty bomb" types as on a battlefield or similar environments. Shoulder straps and a chest strap are provided for wearing the apparatus on a user's back, or other means such as a shoulder pouch can also be employed. Emergency substitution of filter media using thermal insulation from the clothing of the user is available upon depletion of the normal media material.