is only short-lived. Carbon (most often graphite) particles present in the smokes can also serve to absorb the beams of laser designators. Yet another possibility is a water fog sprayed around the vehicle; the presence of large droplets absorbs in infrared band and additionally serves as a countermeasure against radars in 94 GHz band. Other materials used as visible/infrared obscurants are micro-pulverized flakes of brass or graphite, particles of titanium dioxide, or terephthalic acid. Older systems for production of infrared smoke work as generators of aerosol of dust with controlled particle size. Most contemporary vehicle-mounted systems use this approach. However, the aerosol stays airborne only for a short time. The brass particles used in some infrared smoke grenades are typically composed of 70% copper and 30% zinc. They are shaped as irregular flakes with a diameter of about 1.7 µm and thickness of 80–320 nm. Some experimental obscurants work in both infrared and millimeter wave region. They include carbon fibers, metal coated fibers or glass particles, metal microwires, particles of iron and of suitable polymers. Chemicals used Zinc chloride Zinc chloride smoke is grey-white and consists of tiny particles of zinc chloride. The most common mixture for generating these is a zinc chloride smoke mixture (HC), consisting of hexachloroethane, grained aluminium and zinc oxide. The smoke consists of zinc chloride, zinc oxychlorides, and hydrochloric acid, which absorb the moisture in the air. The smoke also contains traces of organic chlorinated compounds, phosgene, carbon monoxide, and chlorine. Its toxicity is caused mainly by the content of strongly acidic hydrochloric acid, but also due to thermal effects of reaction of zinc chloride with water. These effects cause lesions of the mucous membranes of the upper airways. Damage of the lower airways can manifest itself later as well, due to fine particles of zinc chloride and traces of phosgene. In high concentrations the smoke can be very dangerous when inhaled. Symptoms include dyspnea, retrosternal pain, hoarseness, stridor, lachrymation, cough, expectoration, and in some cases haemoptysis. Delayed pulmonary edema, cyanosis or bronchopneumonia may develop. The smoke and the spent canisters contain suspected carcinogens. The prognosis for the casualties depends on the degree of the pulmonary damage. All exposed individuals should be kept under observation for 8 hours. Most affected individuals recover within several days, with some symptoms persisting for up to 1–2 weeks. Severe cases can suffer of reduced pulmonary function for some months,