  Aging phenomena constitute one of the most complex and serious potential
problems which could limit, or severely impair, the use of gaseous detectors in
unprecedented harsh radiation environments. Long-term operation in
high-intensity experiments of the LHC-era not only demands extraordinary
radiation hardness of construction materials and gas mixtures but also very
specific and appropriate assembly procedures and quality checks during detector
construction and testing. Recent experimental data from hadron beams is
discussed. It is shown that the initial stage of radiation tests, usually
performed under isolated laboratory conditions, may not offer the full
information needed to extrapolate to the long-term performance of real and
full-size detectors at high energy physics facilities. Major factors, closely
related to the capability of operating at large localized ionization densities,
and which could lead to operation instabilities and subsequent aging phenomena
in gaseous detectors, are summarized. Finally, an overview of aging experience
with state-of-the-art gas detectors in experiments with low- and high-intensity
radiation environments is given with a goal of providing a set of rules, along
with some caveat, for the construction and operation of gaseous detectors in
high luminosity experiments.
