You may want to add what's called a "conformal coating" to the connections to keep dust and moisture away. This is basically a clear coating that conforms to the surface of your parts, and there are many different kinds. In some military applications, they actually embed circuits in a solid chunk of epoxy or silicone to safeguard them. Note that if the circuit needs to be repaired, these coatings can be very difficult to remove.

Various encapsulation materials