Fire extinguisher had been developed by DuPont and the US Army in 1954. Both 1211 and 1301 work by inhibiting the chain reaction of the fire, and in the case of Halon 1211, cooling class A fuels as well. Halon is still in use today but is falling out of favor for many uses due to its environmental impact. Europe and Australia have severely restricted its use, since the Montreal Protocol of 1987. Less severe restrictions have been implemented in the United States, the Middle East, and Asia. Internationally there are several accepted classification methods for hand-held fire extinguisher. Each classification is
Fire extinguisher so that the sign is not only excited at very low ambient light levels (25 lux), but also has effective luminance intensity and longevity, making the life-safety message conspicuous in the event of power failure, or if smoke obscures emergency ceiling lights. The Photoluminescent Safety Products Association (PSPA) has guidance classifications for luminance performance to help users with applications under "International Maritime Organization Emergency Equipment and Life-saving Appliance Location Requirements," and worldwide industrial fire-safety management requirements. Photo-luminescent signs are sometimes wrongfully described as being reflective. A reflective material will only return ambient light for as long as the light source