Practical considerations must not be overlooked; it is often unfeasible to implement a global
control program all at once. The most urgent problems have to be solved first; priorities have
to be set up. In certain cases, the solution may be found in a combination of measures which by
themselves would not be enough; for example, to achieve part of the required reduction through
environmental measures and to complement them with personal measures (e.g. wearing hearing
protection for only 2-3 hours), bearing in mind that it is extremely difficult to make sure that
hearing protection is properly fitted and properly worn.