It appears that Omega-3, already used widely as a preventative countermeasure for many serious disorders, may help defend against the ill-effects of air pollution as well. Omega-3 supplements have already been recommended to combat poor circulation, rheumatoid arthritis, heart disease, depression and anxiety, as well as showing potential benefits for sufferers of Parkinson's and Alzheimer's. After conducting a study in Mexico City, one of the most notoriously polluted major metropolises in the world, researchers have found that supplementation with Omega-3 appears to protect heart against the adverse effects of air-borne pollutants.
Though the study was rather limited in its number of participants , there appears to be a very promising foundation for further study with a greater number of participants. A full article of the study from Environmental Health Perspectives can be viewed here.