What are the Remedies and Effect of dust, temperature and virus in computer?

They will all make computers cease to function is not properly controlled.

DUST:
Effect-higher temperatures and poor air flow.
Remedy-remove

VIRUS:
Effect-slow machine, possible hijack which can also infect others.
Remedy-remove

TEMPERATURE:
Effect-keep hot stuff cool. (See DUST).
Remedy-keep thermal paste fresh, insure good air flow. (See DUST)

Sounds like homework!