[1]. Wikipedia Air Pollution Page https://en.wikipedia.org/wiki/Air_pollution
[2]. Chen, H; Goldberg, M. S.; Villeneuve, P. J. (2008). "A systematic review of the relation between long-term exposure to ambient air pollution and chronic diseases". Reviews on environmental health. 23 (4): 243-97.
[3]. Purchased from Amazon. https://www.amazon.com/Cerium-Oxide-Glass-Polishing-Powder/dp/B005HVEE7M
[4]. U.S. Food and Drug Administration https://www.fda.gov/MedicalDevices/ProductsandMedicalProcedures/GeneralHospitalGeneralHospitalDev/PersonalProtectiveEquipment/ucm055977.htm
