JOULE –  Most scientists and engineers in the UV business now use the units “mJ/cm2” (millijoule per square centimeter) or “J/m2” (joule per square meter) for UV dose (the correct term is “fluence”). The units “J/m2” are used in most parts of the world except for North America, where “mJ/cm2” are used (1 mJ/cm2 = 10 J/m2. The old term “mW-s/cm2” (milliwatt-second per square centimeter) is equivalent to “mJ/cm2”, since a “W-s” is the same as a “J” (joule). Note that 1000 microwatt = 1 milliwatt
 
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