The output power of a light-emitting diode (LED) not only is affected by aging but also by dirt buildup. Environment
and surroundings are typically characterized by the presence of substances, dust, liquids or vapors that may stick to the
LED, reducing its light output. Knowing the effect of dirt on light output, manufacturers and users can efficiently design
a cleaning or maintenance program. In this work, both 5-mm LEDs and high-power LEDs were subjected to output
power tests for different degrees and types of dirt. In particular, I measure the light flux changes due to deposition of
dust (sand), drops of water, coal dust, oil drops, fat (soldering paste), and fingerprints.