flare burned for less than four minutes and the candlepower was about 40,000 lumens. Countermeasure A special variety of flares is used in military aircraft as a defensive countermeasure against heat-seeking missiles. These flares are usually discharged individually or in salvos by the pilot or automatically by tail-warning devices, and are accompanied by vigorous evasive maneuvering. Since they are intended to deceive infrared missiles, these flares burn at temperatures of thousands of degrees, incandescing in the visible spectrum as well. Tripflares Flares connected to tripwires are used to guard an area against infiltration. The flare begins burning when the tripwire is triggered, providing both alarm and illumination. Regulation Under the UN hazard number system, pyrotechnic flares are designated class 1.4 explosives. Several U.S. states, including California and Massachusetts, have begun regulating levels of potassium perchlorate, which can be unsafe at certain levels in drinking water. Contaminated drinking water can lead to such symptoms as gastric irritation, nausea, vomiting, fever, skin rashes, and even fatal aplastic anemia (a reduction in all types of blood cells). Chemistry Flares produce their light through the combustion of a pyrotechnic composition. The ingredients are varied, but often based on strontium nitrate, potassium nitrate, or potassium perchlorate, mixed with a fuel such as charcoal, sulfur, sawdust, aluminium, magnesium, or a suitable polymeric resin. Flares may be colored by the inclusion of pyrotechnic colorants. Calcium flares are used underwater to illuminate submerged objects. *Note- Fusees manufactured in the United States no longer use potassium perchlorate as an oxidizer and do not contain aluminium or magnesium. Perchlorate flare health issues Many in-service colored signal flares and spectrally balanced decoy flares contain perchlorate oxidizers. Perchlorate, a type of salt in its solid form, dissolves and moves rapidly in groundwater and surface water. Even in low concentrations in drinking water supplies, perchlorate is known to inhibit the uptake of iodine by the thyroid gland. While there are currently no US federal drinking water standards for perchlorate, some states have established public health goals or action levels, and some are in the process of establishing state maximum contaminant levels. For example, the US Environmental Protection Agency has studied the impacts of perchlorate on the environment as well as drinking water. California has also issued guidance regarding perchlorate use. US courts have taken action regarding the use of perchlorate in manufacturing pyrotechnic devices such as flares. For example, in 2003, a federal