Is it dangerous to work on volcanoes and what precautions do scientists take?

Restless volcanoes can be very dangerous places, but it's possible to work safely around them if you're properly prepared. First and foremost, scientists protect themselves by working as a team to create a 'safety net' in which all the important bases are covered. Like a professional driving team, a volcano-response team includes key staff who know the monitoring equipment extremely well, experts in several scientific disciplines who can interpret data coming back from the field, a spokesperson to communicate warnings and other information to public officials and the media, and a scientist-in-charge, or 'driver,' who assumes overall responsibility for team performance. As part of an experienced scientific team capable of quickly assessing the past behavior of a restless volcano, installing instruments to take its pulse, and analyzing all available information to understand what the volcano is doing, a modern volcanologist is prepared to work safely even in the hazardous environment of a restless volcano.

The USGS poster Geologic Hazards of Volcanoes depicts many of the hazards associated with a volcanic eruption.