Each filters type has a primary use in a specific environment. The City filter uses Dynamic Activated Charcoal Cloth (DACC) a 95% pure charcoal weave, originally developed by the U.K. Ministry of Defence for use in the protection against chemical and bacteria warfare situations. We use DACC to effectively filter out Primary pollutants associated with vehicle exhaust emissions. The DACC is laminated with medical grade non woven polypropylene material which filters particulates from the air and helps prevent them from entering the respiratory system. The City filter offers protection against: – Hydrocarbons. e.g. Benzene; Pyrene;1,3 Butadiene. – Acid gases. e.g. Nitrogen dioxide; Sulphur dioxide. – Photo-chemical pollutants. e.g. Low level Ozone – Particulates. e.g. Black smoke; Pollen; Lead oxide. For a more comprehensive list of all the chemicals that have tested with DACC, please go to the Industrial section of the website. The Sportsta filter uses electrostatically charged fibres to attract airborne particulates down to 0.3 microns in size. 1 Micron = 1/1000mm. Unlike most particle filters which rely on mechanical retention, which inherently results in high inhalation resistance or very large cumbersome filters, the Sportsta filter offers extremely low inhalation resistance, by like comparison. The Sportsta filter offers protection against: – Pollen dust; Building dust; Clay dust; Grain dust; Soya dust; Carbon dust; House dust; Cigarette smoke. – PM10’s. e.g. Diesel smoke. – Lead & Tar.