The lux (symbol: lx) is the SI unit of illuminance and luminous emittance measuring luminous power per area. It is used in photometry as a measure of the intensity, as perceived by the human eye, of light that hits or passes through a surface. It is analogous to the radiometric unit watts per square metre, but with the power at each wavelength weighted according to the luminosity function, a standardized model of human visual brightness perception. In English, “lux” is used in both singular and plural.
In the EU-GMP guide you can find general requirements on the ligthing or the light fittings in items 3.3, 3.10 or 3.16.
Normal industrial practice is 200- 250 LUX in normal working areas.
500 to 600 Lux in Inspection area
650 to 700 LUX in documentation areas.
You must not have more LUX as it might add to heat in cleanroms and thus it generates more load on HVAC systems to keep them with in the controlled temeratures as per cGMP Guidance.
footcandles (lumens/square foot) x 10.764 = lux (lumens/square meter)