Virtually every material releases to the space around it volatile organic compounds or other particles.
Most of the coatings currently existing in industry exude particles in a significant manner, and they can affect the functioning of the system.
For example, optical lenses intended for photography for long distances with high resolution (photography from space) have been damaged by particles that were exuded from the coating and settled on the lenses.
In a research, conducted by NASA, it was found that the parylene coating exudes particles to a very small extent, a percentage that does not harm lenses found in its vicinity.
Following the results of this research, NASA and similar entities began to coat the electronic circuits found near the lenses with parylene only.
The following are data from this research that show the percentage emission of volatile materials (outgasing) of the parylene, by the various manufacturers: